[svn-r23473] Update the VOL plugin callbacks with better async I/O support:

 - change hid_t req in callbacks to void **req
 - change all callbacks to accept dxpl_ids (except dataset write and read which already do)
 - update all the private and public VL routines to accept a dxpl_id and event queue id
 - Add an async class for the VOL plugin with cancel, test, and wait request operations
 - add the external VOL log plugin test to the examples directory

NOTE that async operations are still not provided by the HDF5 API, so
all event queue IDs and requests passed to all plugins are NULL for
now.

Tested on jam.

25 files changed, 904 insertions, 676 deletions

diff --git a/src/H5A.c b/src/H5A.c
index dca48e5..d7eb7d9 100644
--- a/src/H5A.c
+++ b/src/H5A.c
@@ -272,7 +272,8 @@ H5Acreate2(hid_t loc_id, const char *attr_name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin, attr_name, acpl_id, aapl_id, H5_REQUEST_NULL)))
+    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin, attr_name, acpl_id, aapl_id, 
+                                        H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create attribute")
 
     /* Get an atom for the attribute */
@@ -281,7 +282,7 @@ H5Acreate2(hid_t loc_id, const char *attr_name, hid_t type_id, hid_t space_id,
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* H5Acreate2() */
@@ -370,7 +371,7 @@ H5Acreate_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin, attr_name, acpl_id, aapl_id, H5_REQUEST_NULL)))
+    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin, attr_name, acpl_id, aapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create attribute")
 
     /* Get an atom for the attribute */
@@ -379,7 +380,7 @@ H5Acreate_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* H5Acreate_by_name() */
@@ -434,7 +435,7 @@ H5Aopen(hid_t loc_id, const char *attr_name, hid_t aapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, attr_name, aapl_id, H5_REQUEST_NULL)))
+    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, attr_name, aapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open attribute")
 
     /* Get an atom for the attribute */
@@ -443,7 +444,7 @@ H5Aopen(hid_t loc_id, const char *attr_name, hid_t aapl_id)
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen() */
@@ -510,7 +511,7 @@ H5Aopen_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, attr_name, aapl_id, H5_REQUEST_NULL)))
+    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, attr_name, aapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open attribute")
 
     /* Get an atom for the attribute */
@@ -519,7 +520,7 @@ H5Aopen_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen_by_name() */
@@ -595,7 +596,7 @@ H5Aopen_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, NULL, aapl_id, H5_REQUEST_NULL)))
+    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, NULL, aapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open attribute")
 
     /* Get an atom for the attribute */
@@ -604,7 +605,7 @@ H5Aopen_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen_by_idx() */
@@ -648,7 +649,7 @@ H5Awrite(hid_t attr_id, hid_t dtype_id, const void *buf)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid attribute identifier")
 
     /* write the data through the VOL */
-    if((ret_value = H5VL_attr_write(attr, vol_plugin, dtype_id, buf, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_attr_write(attr, vol_plugin, dtype_id, buf, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_READERROR, FAIL, "can't read data")
 
 done:
@@ -694,7 +695,7 @@ H5Aread(hid_t attr_id, hid_t dtype_id, void *buf)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid attribute identifier")
 
     /* Read the data through the VOL */
-    if((ret_value = H5VL_attr_read(attr, vol_plugin, dtype_id, buf, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_attr_read(attr, vol_plugin, dtype_id, buf, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_READERROR, FAIL, "can't read data")
 
 done:
@@ -736,7 +737,7 @@ H5Aget_space(hid_t attr_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid attribute identifier")
 
     /* get the dataspace through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_SPACE, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_SPACE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get data space")
 
 done:
@@ -778,7 +779,7 @@ H5Aget_type(hid_t attr_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid attribute identifier")
 
     /* get the datatype through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_TYPE, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_TYPE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get type")
 
 done:
@@ -825,7 +826,7 @@ H5Aget_create_plist(hid_t attr_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid attribute identifier")
 
     /* get the acpl through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_ACPL, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_ACPL, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get acpl")
 
 done:
@@ -880,7 +881,7 @@ H5Aget_name(hid_t attr_id, size_t buf_size, char *buf)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid attribute identifier")
 
     /* get the name through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_NAME, H5_REQUEST_NULL, loc_params, buf_size, buf, &ret_value) < 0)
+    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_NAME, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, loc_params, buf_size, buf, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get name")
 
 done:
@@ -950,17 +951,17 @@ H5Aget_name_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* get the name through the VOL */
-    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_GET_NAME, H5_REQUEST_NULL, 
+    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_GET_NAME, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                      loc_params, size, name, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get name")
 
 #if 0
-    if(H5VL_object_misc(loc_id, H5VL_ATTR_OPEN_BY_IDX, H5_REQUEST_NULL, &attr_id, 
+    if(H5VL_object_misc(loc_id, H5VL_ATTR_OPEN_BY_IDX, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &attr_id, 
                          obj_name, idx_type, order, n, H5P_DEFAULT, lapl_id) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTINIT, FAIL, "unable to open attribute")
 
     /* get the name through the VOL */
-    if(H5VL_attr_get(attr_id, H5VL_ATTR_GET_NAME, H5_REQUEST_NULL, &ret_value, size, name) < 0)
+    if(H5VL_attr_get(attr_id, H5VL_ATTR_GET_NAME, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value, size, name) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get name")
 #endif
 
@@ -1004,7 +1005,7 @@ H5Aget_storage_size(hid_t attr_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "invalid attribute identifier")
 
     /* get the storage size through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_STORAGE_SIZE, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_STORAGE_SIZE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, 0, "unable to get acpl")
 
 done:
@@ -1047,7 +1048,7 @@ H5Aget_info(hid_t attr_id, H5A_info_t *ainfo)
     loc_params.obj_type = H5I_get_type(attr_id);
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_INFO, H5_REQUEST_NULL, loc_params, ainfo) < 0)
+    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_INFO, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, loc_params, ainfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
 done:
@@ -1108,20 +1109,20 @@ H5Aget_info_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_GET_INFO, H5_REQUEST_NULL, loc_params, ainfo, attr_name) < 0)
+    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_GET_INFO, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, loc_params, ainfo, attr_name) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
 #if 0
     /* Open the attribute through the VOL */
-    if((attr_id = H5VL_attr_open(loc_id, loc_params, attr_name, H5P_DEFAULT, H5_REQUEST_NULL)) < 0)
+    if((attr_id = H5VL_attr_open(loc_id, loc_params, attr_name, H5P_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CANTINIT, FAIL, "unable to open attribute")
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(attr_id, H5VL_ATTR_GET_INFO, H5_REQUEST_NULL, ainfo) < 0)
+    if(H5VL_attr_get(attr_id, H5VL_ATTR_GET_INFO, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, ainfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
     /* release resources */
-    if(attr_id > 0 && H5VL_attr_close(attr_id, H5_REQUEST_NULL) < 0)
+    if(attr_id > 0 && H5VL_attr_close(attr_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
         HDONE_ERROR(H5E_ATTR, H5E_CANTFREE, FAIL, "can't close attribute")
 
 #endif
@@ -1191,7 +1192,7 @@ H5Aget_info_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_GET_INFO, H5_REQUEST_NULL, 
+    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_GET_INFO, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                      loc_params, ainfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
@@ -1205,16 +1206,16 @@ H5Aget_info_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
 	HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "unable to get attribute info")
 
     /* open the attribute through the VOL */
-    if(H5VL_object_misc(loc_id, H5VL_ATTR_OPEN_BY_IDX, H5_REQUEST_NULL, &attr_id, 
+    if(H5VL_object_misc(loc_id, H5VL_ATTR_OPEN_BY_IDX, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &attr_id, 
                          obj_name, idx_type, order, n, H5P_DEFAULT, lapl_id) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTINIT, FAIL, "unable to open attribute")
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(attr_id, H5VL_ATTR_GET_INFO, H5_REQUEST_NULL, ainfo) < 0)
+    if(H5VL_attr_get(attr_id, H5VL_ATTR_GET_INFO, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, ainfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
     /* Release resources */
-    if(attr_id && H5VL_attr_close(attr_id, H5_REQUEST_NULL) < 0)
+    if(attr_id && H5VL_attr_close(attr_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
         HDONE_ERROR(H5E_ATTR, H5E_CANTFREE, FAIL, "can't close attribute")
 #endif
 
@@ -1267,7 +1268,7 @@ H5Arename(hid_t loc_id, const char *old_name, const char *new_name)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
         /* rename the attribute info through the VOL */
-        if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_ATTR_RENAME, H5_REQUEST_NULL, 
+        if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_ATTR_RENAME, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                             old_name, new_name) < 0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTRENAME, FAIL, "can't rename attribute")
     }
@@ -1333,7 +1334,7 @@ H5Arename_by_name(hid_t loc_id, const char *obj_name, const char *old_attr_name,
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
         /* rename the attribute info through the VOL */
-        if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_ATTR_RENAME, H5_REQUEST_NULL, 
+        if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_ATTR_RENAME, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                             old_attr_name, new_attr_name) < 0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTRENAME, FAIL, "can't rename attribute")
     } /* end if */
@@ -1597,7 +1598,7 @@ H5Adelete(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Open the attribute through the VOL */
-    if(H5VL_attr_remove(obj, loc_params, vol_plugin, name, H5_REQUEST_NULL) < 0)
+    if(H5VL_attr_remove(obj, loc_params, vol_plugin, name, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete attribute")
 
 done:
@@ -1659,7 +1660,7 @@ H5Adelete_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Open the attribute through the VOL */
-    if(H5VL_attr_remove(obj, loc_params, vol_plugin, attr_name, H5_REQUEST_NULL) < 0)
+    if(H5VL_attr_remove(obj, loc_params, vol_plugin, attr_name, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete attribute")
 
 done:
@@ -1734,7 +1735,7 @@ H5Adelete_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Open the attribute through the VOL */
-    if(H5VL_attr_remove(obj, loc_params, vol_plugin, NULL, H5_REQUEST_NULL) < 0)
+    if(H5VL_attr_remove(obj, loc_params, vol_plugin, NULL, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete attribute")
 
 #if 0
@@ -1743,7 +1744,7 @@ H5Adelete_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.loc_data.loc_by_name.plist_id = lapl_id;
 
     /* get the attribute info through the VOL */
-    if(H5VL_object_misc(loc_id, H5VL_ATTR_DELETE_BY_IDX, H5_REQUEST_NULL, loc_params, 
+    if(H5VL_object_misc(loc_id, H5VL_ATTR_DELETE_BY_IDX, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, loc_params, 
                         idx_type, order, n) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 #endif
@@ -1831,7 +1832,7 @@ H5Aexists(hid_t obj_id, const char *attr_name)
     loc_params.obj_type = H5I_get_type(obj_id);
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_EXISTS, H5_REQUEST_NULL, loc_params, attr_name, &ret_value) < 0)
+    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_EXISTS, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, loc_params, attr_name, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
 done:
@@ -1890,7 +1891,7 @@ H5Aexists_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_EXISTS, H5_REQUEST_NULL, loc_params, attr_name, &ret_value) < 0)
+    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_EXISTS, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, loc_params, attr_name, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
 done:
@@ -1920,7 +1921,7 @@ H5A_close_attr(void *attr, H5VL_t *vol_plugin)
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Close the attr through the VOL*/
-    if((ret_value = H5VL_attr_close(attr, vol_plugin, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_attr_close(attr, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to close attribute")
 
 done:
diff --git a/src/H5Adeprec.c b/src/H5Adeprec.c
index 2cc3b80..248b969 100644
--- a/src/H5Adeprec.c
+++ b/src/H5Adeprec.c
@@ -181,7 +181,7 @@ H5Acreate1(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin, name, plist_id, H5P_DEFAULT, H5_REQUEST_NULL)))
+    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin, name, plist_id, H5P_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create attribute")
 
     /* Get an atom for the attribute */
@@ -190,7 +190,7 @@ H5Acreate1(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* H5Acreate1() */
@@ -248,7 +248,7 @@ H5Aopen_name(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, name, H5P_DEFAULT, H5_REQUEST_NULL)))
+    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, name, H5P_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open attribute")
 
     /* Get an atom for the attribute */
@@ -257,7 +257,7 @@ H5Aopen_name(hid_t loc_id, const char *name)
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen_name() */
@@ -317,7 +317,7 @@ H5Aopen_idx(hid_t loc_id, unsigned idx)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, NULL, H5P_DEFAULT, H5_REQUEST_NULL)))
+    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, NULL, H5P_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open attribute")
 
     /* Get an atom for the attribute */
@@ -326,7 +326,7 @@ H5Aopen_idx(hid_t loc_id, unsigned idx)
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen_idx() */
@@ -374,7 +374,7 @@ H5Aget_num_attrs(hid_t loc_id)
 
     /* Get the group info through the VOL using the location token */
     if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_GET_INFO, 
-                       H5_REQUEST_NULL, &oinfo) < 0)
+                       H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &oinfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
     ret_value = oinfo.num_attrs;
diff --git a/src/H5D.c b/src/H5D.c
index 5a6d252..399e67c 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -195,7 +195,7 @@ H5Dcreate2(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the dataset through the VOL */
-    if(NULL == (dset = H5VL_dataset_create(obj, loc_params, vol_plugin, name, dcpl_id, dapl_id, H5_REQUEST_NULL)))
+    if(NULL == (dset = H5VL_dataset_create(obj, loc_params, vol_plugin, name, dcpl_id, dapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset")
 
     /* Get an atom for the dataset */
@@ -204,7 +204,7 @@ H5Dcreate2(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
 
 done:
     if (ret_value < 0 && dset)
-        if(H5VL_dataset_close (dset, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_dataset_close (dset, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Dcreate2() */
@@ -295,7 +295,7 @@ H5Dcreate_anon(hid_t loc_id, hid_t type_id, hid_t space_id, hid_t dcpl_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the dataset through the VOL */
-    if(NULL == (dset = H5VL_dataset_create(obj, loc_params, vol_plugin, NULL, dcpl_id, dapl_id, H5_REQUEST_NULL)))
+    if(NULL == (dset = H5VL_dataset_create(obj, loc_params, vol_plugin, NULL, dcpl_id, dapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset")
 
     /* Get an atom for the dataset */
@@ -304,7 +304,7 @@ H5Dcreate_anon(hid_t loc_id, hid_t type_id, hid_t space_id, hid_t dcpl_id,
 
 done:
     if (ret_value < 0 && dset)
-        if(H5VL_dataset_close (dset, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_dataset_close (dset, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Dcreate_anon() */
@@ -362,7 +362,7 @@ H5Dopen2(hid_t loc_id, const char *name, hid_t dapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the dataset through the VOL */
-    if(NULL == (dset = H5VL_dataset_open(obj, loc_params, vol_plugin, name, dapl_id, H5_REQUEST_NULL)))
+    if(NULL == (dset = H5VL_dataset_open(obj, loc_params, vol_plugin, name, dapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset")
 
     /* Get an atom for the dataset */
@@ -371,7 +371,7 @@ H5Dopen2(hid_t loc_id, const char *name, hid_t dapl_id)
 
 done:
     if (ret_value < 0 && dset)
-        if(H5VL_dataset_close (dset, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_dataset_close (dset, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Dopen2() */
@@ -416,7 +416,7 @@ H5Dclose(hid_t dset_id)
 
 #if 0
     /* Close the dataset through the VOL */
-    if((ret_value = H5VL_dataset_close(dset_id, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_dataset_close(dset_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTRELEASE, FAIL, "unable to close dataset")
 #endif
 
@@ -459,7 +459,7 @@ H5Dget_space(hid_t dset_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid dataset identifier")
 
     /* get the dataspace through the VOL */
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_SPACE, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_SPACE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get data space")
 done:
     FUNC_LEAVE_API(ret_value)
@@ -498,7 +498,7 @@ H5Dget_space_status(hid_t dset_id, H5D_space_status_t *allocation)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid dataset identifier")
 
     /* Read data space address through the VOL and return */
-    if((ret_value=H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_SPACE_STATUS, H5_REQUEST_NULL, allocation)) < 0)
+    if((ret_value=H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_SPACE_STATUS, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, allocation)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get space status")
 
 done:
@@ -540,7 +540,7 @@ H5Dget_type(hid_t dset_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid dataset identifier")
 
     /* get the datatype through the VOL */
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_TYPE, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_TYPE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get datatype")
 
 done:
@@ -581,7 +581,7 @@ H5Dget_create_plist(hid_t dset_id)
     if(NULL == (dset = (void *)H5I_object(dset_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid dataset identifier")
 
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_DCPL, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_DCPL, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get dataset creation properties")
 
 done:
@@ -639,7 +639,7 @@ H5Dget_access_plist(hid_t dset_id)
     if(NULL == (dset = (void *)H5I_object(dset_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid dataset identifier")
 
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_DAPL, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_DAPL, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get dataset access properties")
 done:
 
@@ -683,7 +683,7 @@ H5Dget_storage_size(hid_t dset_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "invalid dataset identifier")
 
     /* get storage size through the VOL */
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_STORAGE_SIZE, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_STORAGE_SIZE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, 0, "unable to get storage size")
 
 done:
@@ -723,7 +723,7 @@ H5Dget_offset(hid_t dset_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, HADDR_UNDEF, "invalid dataset identifier")
 
     /* get offset through the VOL */
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_OFFSET, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_OFFSET, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, HADDR_UNDEF, "unable to get offset")
 
 done:
@@ -930,7 +930,7 @@ H5Dvlen_get_buf_size(hid_t dataset_id, hid_t type_id, hid_t space_id,
         if(NULL == (dset = (void *)H5I_object(dataset_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid dataset identifier")
         /* Get a copy of the dataspace ID */
-        if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_SPACE, H5_REQUEST_NULL, &(vlen_bufsize.fspace_id)) < 0)
+        if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_SPACE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &(vlen_bufsize.fspace_id)) < 0)
             HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "can't copy dataspace")
     }
 #endif
@@ -1021,7 +1021,7 @@ H5Dset_extent(hid_t dset_id, const hsize_t size[])
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid dataset identifier")
 
     /* set the extent through the VOL */
-    if((ret_value = H5VL_dataset_set_extent(dset, vol_plugin, size, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_dataset_set_extent(dset, vol_plugin, size, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to set extent of dataset")
 
 done:
@@ -1051,7 +1051,7 @@ H5D_close_dataset(void *dset, H5VL_t *vol_plugin)
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Close the dataset through the VOL*/
-    if((ret_value = H5VL_dataset_close(dset, vol_plugin, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_dataset_close(dset, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to close dataset")
 
 done:
diff --git a/src/H5Ddeprec.c b/src/H5Ddeprec.c
index 15dc409..a9c94a4 100644
--- a/src/H5Ddeprec.c
+++ b/src/H5Ddeprec.c
@@ -183,7 +183,7 @@ H5Dcreate1(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
 
     /* Create the dataset through the VOL */
     if(NULL == (dset = H5VL_dataset_create(obj, loc_params, vol_plugin, name, dcpl_id, 
-                                           H5P_DATASET_ACCESS_DEFAULT, H5_REQUEST_NULL)))
+                                           H5P_DATASET_ACCESS_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset")
 
     /* Get an atom for the dataset */
@@ -192,7 +192,7 @@ H5Dcreate1(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
 
 done:
     if (ret_value < 0 && dset)
-        if(H5VL_dataset_close (dset, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_dataset_close (dset, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Dcreate1() */
@@ -244,7 +244,7 @@ H5Dopen1(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the dataset through the VOL */
-    if(NULL == (dset = H5VL_dataset_open(obj, loc_params, vol_plugin, name, dapl_id, H5_REQUEST_NULL)))
+    if(NULL == (dset = H5VL_dataset_open(obj, loc_params, vol_plugin, name, dapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset")
 
     /* Get an atom for the dataset */
@@ -253,7 +253,7 @@ H5Dopen1(hid_t loc_id, const char *name)
 
 done:
     if (ret_value < 0 && dset)
-        if(H5VL_dataset_close (dset, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_dataset_close (dset, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Dopen1() */
diff --git a/src/H5Dio.c b/src/H5Dio.c
index e08e079..25af0f5 100644
--- a/src/H5Dio.c
+++ b/src/H5Dio.c
@@ -143,7 +143,7 @@ H5Dread(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
 
     /* Read the data through the VOL */
     if((ret_value = H5VL_dataset_read(dset, vol_plugin, mem_type_id, mem_space_id, 
-                                      file_space_id, plist_id, buf, H5_REQUEST_NULL)) < 0)
+                                      file_space_id, plist_id, buf, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "can't read data")
 
 
@@ -215,7 +215,7 @@ H5Dwrite(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
 
     /* Write the data through the VOL */
     if((ret_value = H5VL_dataset_write(dset, vol_plugin, mem_type_id, mem_space_id, 
-                                       file_space_id, dxpl_id, buf, H5_REQUEST_NULL)) < 0)
+                                       file_space_id, dxpl_id, buf, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "can't write data")
 
 done:
diff --git a/src/H5F.c b/src/H5F.c
index d525a9f..2c86184 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -214,7 +214,7 @@ H5Fget_create_plist(hid_t file_id)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_FCPL, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_FCPL, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file creation properties")
 
 done:
@@ -260,7 +260,7 @@ H5Fget_access_plist(hid_t file_id)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_FAPL, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_FAPL, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file creation properties")
 
 done:
@@ -303,7 +303,7 @@ H5Fget_obj_count(hid_t file_id, unsigned types)
         if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(file_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-        if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_COUNT, H5_REQUEST_NULL, types, &ret_value) < 0)
+        if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_COUNT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, types, &ret_value) < 0)
             HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get object count in file(s)")
     }
     /* iterate over all open files and get the obj count for each */
@@ -363,7 +363,7 @@ H5Fget_obj_ids(hid_t file_id, unsigned types, size_t max_objs, hid_t *oid_list)
         if(NULL == (obj = (void *)H5I_object(file_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-        if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_IDS, H5_REQUEST_NULL, 
+        if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_IDS, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                          types, max_objs, oid_list, &ret_value) < 0)
             HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get object count in file(s)")
     }
@@ -422,7 +422,7 @@ H5Fget_vfd_handle(hid_t file_id, hid_t fapl, void **file_handle)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
     if((ret_value = H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_VFD_HANDLE, 
-                                       H5_REQUEST_NULL, file_handle, fapl)) < 0)
+                                       H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, file_handle, fapl)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file handle")
 
 done:
@@ -462,7 +462,7 @@ H5Fis_accessible(const char *name, hid_t fapl_id)
         if(TRUE != H5P_isa_class(fapl_id, H5P_FILE_ACCESS))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not file access property list")
 
-    if(H5VL_file_misc(NULL, NULL, H5VL_FILE_IS_ACCESSIBLE, H5_REQUEST_NULL, 
+    if(H5VL_file_misc(NULL, NULL, H5VL_FILE_IS_ACCESSIBLE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                       fapl_id, name, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file handle")
 
@@ -535,7 +535,7 @@ H5Fcreate(const char *filename, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not file access property list")
 
     /* create a new file or truncate an existing file through the VOL */
-    if(NULL == (file = H5VL_file_create(&vol_plugin, filename, flags, fcpl_id, fapl_id, H5_REQUEST_NULL)))
+    if(NULL == (file = H5VL_file_create(&vol_plugin, filename, flags, fcpl_id, fapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to create file")
 
     /* Get an atom for the file with the VOL information as the auxilary struct*/
@@ -611,7 +611,7 @@ H5Fopen(const char *filename, unsigned flags, hid_t fapl_id)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not file access property list")
 
     /* Open the file through the VOL layer */
-    if(NULL == (file = H5VL_file_open(&vol_plugin, filename, flags, fapl_id, H5_REQUEST_NULL)))
+    if(NULL == (file = H5VL_file_open(&vol_plugin, filename, flags, fapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to create file")
 
     /* Get an atom for the file with the VOL information as the auxilary struct*/
@@ -666,7 +666,7 @@ H5Fflush(hid_t object_id, H5F_scope_t scope)
     loc_params.type = H5VL_OBJECT_BY_SELF;
     loc_params.obj_type = obj_type;
 
-    if((ret_value = H5VL_file_flush(obj, loc_params, vol_plugin, scope, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_file_flush(obj, loc_params, vol_plugin, scope, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTFLUSH, FAIL, "unable to flush file")
 
 done:
@@ -723,7 +723,7 @@ H5Fclose(hid_t file_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
     /* Close the file through the VOL*/
-    if((ret_value = H5VL_file_close(file, vol_plugin, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_file_close(file, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_FILE, H5E_CANTCLOSEFILE, FAIL, "unable to close file")
 
     H5MM_free(vol_plugin);
@@ -756,7 +756,7 @@ H5F_close_file(void *file, H5VL_t *vol_plugin)
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Close the file through the VOL*/
-    if((ret_value = H5VL_file_close(file, vol_plugin, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_file_close(file, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_FILE, H5E_CANTCLOSEFILE, FAIL, "unable to close file")
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -804,7 +804,7 @@ H5Freopen(hid_t file_id)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_REOPEN, H5_REQUEST_NULL, &file) < 0)
+    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_REOPEN, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &file) < 0)
 	HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to reopen file")
 
     if (NULL == file)
@@ -853,7 +853,7 @@ H5Fget_intent(hid_t file_id, unsigned *intent_flags)
         if(NULL == (obj = (void *)H5I_object(file_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-        if((ret_value = H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_INTENT, H5_REQUEST_NULL, intent_flags)) < 0)
+        if((ret_value = H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_INTENT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, intent_flags)) < 0)
             HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file intent")
     }
 
@@ -894,7 +894,7 @@ H5Fget_freespace(hid_t file_id)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_FREE_SPACE, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_FREE_SPACE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file free space")
 
 done:
@@ -938,7 +938,7 @@ H5Fget_filesize(hid_t file_id, hsize_t *size)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if((ret_value = H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_SIZE, H5_REQUEST_NULL, size)) < 0)
+    if((ret_value = H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_SIZE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, size)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file size")
 
 done:
@@ -1010,7 +1010,7 @@ H5Fget_file_image(hid_t file_id, void *buf_ptr, size_t buf_len)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
     /* get image through the VOL */
-    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_FILE_IMAGE, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_FILE_IMAGE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                           buf_ptr, &ret_value, buf_len) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file image")
 
@@ -1059,7 +1059,7 @@ H5Fget_mdc_config(hid_t file_id, H5AC_cache_config_t *config_ptr)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if((ret_value = H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_MDC_CONF, H5_REQUEST_NULL, 
+    if((ret_value = H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_MDC_CONF, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                                        config_ptr)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get mdc configuration")
 
@@ -1100,7 +1100,7 @@ H5Fset_mdc_config(hid_t file_id, H5AC_cache_config_t *config_ptr)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_SET_MDC_CONFIG, H5_REQUEST_NULL, config_ptr) < 0)
+    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_SET_MDC_CONFIG, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, config_ptr) < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "uanvle to set MDC configuration")
 
 done:
@@ -1145,7 +1145,7 @@ H5Fget_mdc_hit_rate(hid_t file_id, double *hit_rate_ptr)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if((ret_value = H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_MDC_HR, H5_REQUEST_NULL, 
+    if((ret_value = H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_MDC_HR, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                                        hit_rate_ptr)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get MDC hit rate")
 
@@ -1191,7 +1191,7 @@ H5Fget_mdc_size(hid_t file_id, size_t *max_size_ptr, size_t *min_clean_size_ptr,
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if((ret_value = H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_MDC_SIZE, H5_REQUEST_NULL, max_size_ptr, 
+    if((ret_value = H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_MDC_SIZE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, max_size_ptr, 
                                        min_clean_size_ptr, cur_size_ptr, cur_num_entries_ptr)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get MDC size")
 
@@ -1238,7 +1238,7 @@ H5Freset_mdc_hit_rate_stats(hid_t file_id)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_RESET_MDC_HIT_RATE, H5_REQUEST_NULL) < 0)
+    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_RESET_MDC_HIT_RATE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
         HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "can't reset cache hit rate")
 
 done:
@@ -1293,7 +1293,7 @@ H5Fget_name(hid_t obj_id, char *name/*out*/, size_t size)
     if(NULL == (obj = (void *)H5VL_get_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_NAME, H5_REQUEST_NULL,
+    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_NAME, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL,
                      type, size, name, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file name")
 
@@ -1348,7 +1348,7 @@ H5Fget_info2(hid_t obj_id, H5F_info2_t *finfo)
     if(NULL == (obj = (void *)H5VL_get_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if((ret_value = H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_INFO, H5_REQUEST_NULL, 
+    if((ret_value = H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_INFO, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                                        type, finfo)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file info")
 done:
@@ -1394,7 +1394,7 @@ H5Fget_free_sections(hid_t file_id, H5F_mem_t type, size_t nsects,
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_FREE_SECTIONS, H5_REQUEST_NULL, sect_info, 
+    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_GET_FREE_SECTIONS, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, sect_info, 
                           &ret_value, type, nsects) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file free sections")
 done:
@@ -1434,7 +1434,7 @@ H5Fclear_elink_file_cache(hid_t file_id)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_CLEAR_ELINK_CACHE, H5_REQUEST_NULL) < 0)
+    if(H5VL_file_optional(obj, vol_plugin, H5VL_FILE_CLEAR_ELINK_CACHE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "can't release external file cache")
 
 done:
diff --git a/src/H5Fint.c b/src/H5Fint.c
index bc196a9..a853140 100644
--- a/src/H5Fint.c
+++ b/src/H5Fint.c
@@ -227,7 +227,7 @@ H5F_get_obj_count_cb(void UNUSED *obj_ptr, hid_t obj_id, void *key)
     if(NULL == (obj = (void *)H5I_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_COUNT, H5_REQUEST_NULL, 
+    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_COUNT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                      udata->types, &obj_count) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, H5_ITER_ERROR, "unable to get object count in file(s)")
 
@@ -303,7 +303,7 @@ H5F_get_obj_ids_cb(void UNUSED *obj_ptr, hid_t obj_id, void *key)
     if(NULL == (obj = (void *)H5I_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_IDS, H5_REQUEST_NULL, udata->types,
+    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_IDS, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, udata->types,
                      udata->max_objs, udata->oid_list, &obj_count) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, H5_ITER_ERROR, "unable to get object count in file(s)")
 
diff --git a/src/H5Fmount.c b/src/H5Fmount.c
index 55f364c..285eccd 100644
--- a/src/H5Fmount.c
+++ b/src/H5Fmount.c
@@ -509,7 +509,7 @@ H5Fmount(hid_t loc_id, const char *name, hid_t child_id, hid_t plist_id)
     if(NULL == (file = (void *)H5I_object(child_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if((ret_value = H5VL_file_misc(obj, vol_plugin1, H5VL_FILE_MOUNT, H5_REQUEST_NULL, 
+    if((ret_value = H5VL_file_misc(obj, vol_plugin1, H5VL_FILE_MOUNT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                                    type, name, file, plist_id)) < 0)
 	HGOTO_ERROR(H5E_FILE, H5E_MOUNT, FAIL, "unable to mount file")
 
@@ -565,7 +565,7 @@ H5Funmount(hid_t loc_id, const char *name)
     if(NULL == (obj = (void *)H5I_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if((ret_value = H5VL_file_misc(obj, vol_plugin, H5VL_FILE_UNMOUNT, H5_REQUEST_NULL, type, name)) < 0)
+    if((ret_value = H5VL_file_misc(obj, vol_plugin, H5VL_FILE_UNMOUNT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, type, name)) < 0)
 	HGOTO_ERROR(H5E_FILE, H5E_MOUNT, FAIL, "unable to unmount file")
 
 done:
diff --git a/src/H5G.c b/src/H5G.c
index 33ef12d..e9502ec 100644
--- a/src/H5G.c
+++ b/src/H5G.c
@@ -325,7 +325,7 @@ H5Gcreate2(hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id, hid_t g
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the group through the VOL */
-    if(NULL == (grp = H5VL_group_create(obj, loc_params, vol_plugin, name, gcpl_id, gapl_id, H5_REQUEST_NULL)))
+    if(NULL == (grp = H5VL_group_create(obj, loc_params, vol_plugin, name, gcpl_id, gapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create group")
 
     /* Get an atom for the group */
@@ -334,7 +334,7 @@ H5Gcreate2(hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id, hid_t g
 
 done:
     if (ret_value < 0 && grp)
-        if(H5VL_group_close (grp, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_group_close (grp, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release group")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Gcreate2() */
@@ -413,7 +413,7 @@ H5Gcreate_anon(hid_t loc_id, hid_t gcpl_id, hid_t gapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the group through the VOL */
-    if(NULL == (grp = H5VL_group_create(obj, loc_params, vol_plugin, NULL, gcpl_id, gapl_id, H5_REQUEST_NULL)))
+    if(NULL == (grp = H5VL_group_create(obj, loc_params, vol_plugin, NULL, gcpl_id, gapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create group")
 
     /* Get an atom for the group */
@@ -422,7 +422,7 @@ H5Gcreate_anon(hid_t loc_id, hid_t gcpl_id, hid_t gapl_id)
 
 done:
     if (ret_value < 0 && grp)
-        if(H5VL_group_close (grp, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_group_close (grp, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release group")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Gcreate_anon() */
@@ -480,7 +480,7 @@ H5Gopen2(hid_t loc_id, const char *name, hid_t gapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the group through the VOL */
-    if(NULL == (grp = H5VL_group_open(obj, loc_params, vol_plugin, name, gapl_id, H5_REQUEST_NULL)))
+    if(NULL == (grp = H5VL_group_open(obj, loc_params, vol_plugin, name, gapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create group")
 
     /* Get an atom for the group */
@@ -489,7 +489,7 @@ H5Gopen2(hid_t loc_id, const char *name, hid_t gapl_id)
 
 done:
     if (ret_value < 0 && grp)
-        if(H5VL_group_close (grp, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_group_close (grp, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release group")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Gopen2() */
@@ -528,7 +528,7 @@ H5Gget_create_plist(hid_t grp_id)
     if(NULL == (grp = (void *)H5I_object(grp_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid group identifier")
 
-    if(H5VL_group_get(grp, vol_plugin, H5VL_GROUP_GET_GCPL, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_group_get(grp, vol_plugin, H5VL_GROUP_GET_GCPL, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group creation properties")
 
 done:
@@ -579,7 +579,7 @@ H5Gget_info(hid_t loc_id, H5G_info_t *grp_info)
     loc_params.obj_type = id_type;
 
     /* Get the group info through the VOL using the location token */
-    if((ret_value = H5VL_group_get(obj, vol_plugin, H5VL_GROUP_GET_INFO, H5_REQUEST_NULL, 
+    if((ret_value = H5VL_group_get(obj, vol_plugin, H5VL_GROUP_GET_INFO, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                                    loc_params, grp_info)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -637,7 +637,7 @@ H5Gget_info_by_name(hid_t loc_id, const char *name, H5G_info_t *grp_info,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid group identifier")
 
     /* Get the group info through the VOL using the location token */
-    if((ret_value = H5VL_group_get(obj, vol_plugin, H5VL_GROUP_GET_INFO, H5_REQUEST_NULL, 
+    if((ret_value = H5VL_group_get(obj, vol_plugin, H5VL_GROUP_GET_INFO, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                                    loc_params, grp_info)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -704,7 +704,7 @@ H5Gget_info_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid group identifier")
 
     /* Get the group info through the VOL using the location token */
-    if((ret_value = H5VL_group_get(obj, vol_plugin, H5VL_GROUP_GET_INFO, H5_REQUEST_NULL, 
+    if((ret_value = H5VL_group_get(obj, vol_plugin, H5VL_GROUP_GET_INFO, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                                    loc_params, grp_info)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -746,7 +746,7 @@ H5Gclose(hid_t group_id)
     	HGOTO_ERROR(H5E_SYM, H5E_CANTRELEASE, FAIL, "unable to close group")
 #if 0
     /* Close the group through the VOL */
-    if(H5VL_group_close(group_id, H5_REQUEST_NULL) < 0)
+    if(H5VL_group_close(group_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTRELEASE, FAIL, "unable to close group")
 #endif
 
@@ -777,7 +777,7 @@ H5G_close_group(void *grp, H5VL_t *vol_plugin)
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Close the group through the VOL*/
-    if((ret_value = H5VL_group_close(grp, vol_plugin, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_group_close(grp, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to close group")
 
 done:
diff --git a/src/H5Gdeprec.c b/src/H5Gdeprec.c
index 5399219..58c791b 100644
--- a/src/H5Gdeprec.c
+++ b/src/H5Gdeprec.c
@@ -263,7 +263,7 @@ H5Gcreate1(hid_t loc_id, const char *name, size_t size_hint)
 
     /* Create the group through the VOL */
     if(NULL == (grp = H5VL_group_create(obj, loc_params, vol_plugin, name, tmp_gcpl, 
-                                        H5P_GROUP_ACCESS_DEFAULT, H5_REQUEST_NULL)))
+                                        H5P_GROUP_ACCESS_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create group")
 
     /* Get an atom for the group */
@@ -275,7 +275,7 @@ done:
         if(H5I_dec_ref(tmp_gcpl) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release property list")
     if (ret_value < 0 && grp)
-        if(H5VL_group_close (grp, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_group_close (grp, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release group")
 
     FUNC_LEAVE_API(ret_value)
@@ -327,7 +327,7 @@ H5Gopen1(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the group through the VOL */
-    if(NULL == (grp = H5VL_group_open(obj, loc_params, vol_plugin, name, H5P_DEFAULT, H5_REQUEST_NULL)))
+    if(NULL == (grp = H5VL_group_open(obj, loc_params, vol_plugin, name, H5P_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create group")
 
     /* Get an atom for the group */
@@ -336,7 +336,7 @@ H5Gopen1(hid_t loc_id, const char *name)
 
 done:
     if (ret_value < 0 && grp)
-        if(H5VL_group_close (grp, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_group_close (grp, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release group")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Gopen1() */
@@ -400,7 +400,7 @@ H5Glink(hid_t cur_loc_id, H5G_link_t type, const char *cur_name, const char *new
 
         /* Create the link through the VOL */
         if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_HARD, NULL, loc_params2, vol_plugin,
-                                         lcpl_id, H5P_DEFAULT, H5_REQUEST_NULL)) < 0)
+                                         lcpl_id, H5P_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
     } /* end if */
     else if(type == H5L_TYPE_SOFT) {
@@ -426,7 +426,7 @@ H5Glink(hid_t cur_loc_id, H5G_link_t type, const char *cur_name, const char *new
 
         /* Create the link through the VOL */
         if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_SOFT, obj, loc_params, vol_plugin, 
-                                         lcpl_id, H5P_DEFAULT, H5_REQUEST_NULL)) < 0)
+                                         lcpl_id, H5P_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
     } /* end else if */
     else
@@ -507,7 +507,7 @@ H5Glink2(hid_t cur_loc_id, const char *cur_name, H5G_link_t type,
         /* Create the link through the VOL */
         if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_HARD, obj2, loc_params2, 
                                          (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2),
-                                         lcpl_id, H5P_DEFAULT, H5_REQUEST_NULL)) < 0)
+                                         lcpl_id, H5P_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
     } /* end if */
     else if(type == H5L_TYPE_SOFT) {
@@ -538,7 +538,7 @@ H5Glink2(hid_t cur_loc_id, const char *cur_name, H5G_link_t type,
 
         /* Create the link through the VOL */
         if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_SOFT, obj, loc_params, vol_plugin, 
-                                         lcpl_id, H5P_DEFAULT, H5_REQUEST_NULL)) < 0)
+                                         lcpl_id, H5P_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
     } /* end else if */
     else
@@ -586,7 +586,7 @@ H5Gmove(hid_t src_loc_id, const char *src_name, const char *dst_name)
 
     /* Create the link through the VOL */
     if((ret_value = H5VL_link_move(obj, loc_params1, NULL, loc_params2, vol_plugin,
-                                   FALSE, H5P_DEFAULT, H5P_DEFAULT, H5_REQUEST_NULL)) < 0)
+                                   FALSE, H5P_DEFAULT, H5P_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -652,7 +652,7 @@ H5Gmove2(hid_t src_loc_id, const char *src_name, hid_t dst_loc_id,
     /* Move the link through the VOL */
     if((ret_value = H5VL_link_move(obj1, loc_params1, obj2, loc_params2, 
                                    (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2), 
-                                   FALSE, H5P_DEFAULT, H5P_DEFAULT, H5_REQUEST_NULL)) < 0)
+                                   FALSE, H5P_DEFAULT, H5P_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -694,7 +694,7 @@ H5Gunlink(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Delete the link through the VOL */
-    if((ret_value = H5VL_link_remove(obj, loc_params, vol_plugin, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_link_remove(obj, loc_params, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -739,7 +739,7 @@ H5Gget_linkval(hid_t loc_id, const char *name, size_t size, char *buf/*out*/)
 
     /* Get the link info through the VOL */
     if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_VAL, 
-                                  H5_REQUEST_NULL, buf, size)) < 0)
+                                  H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, buf, size)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link value")
 
 done:
@@ -791,7 +791,7 @@ H5Gset_comment(hid_t loc_id, const char *name, const char *comment)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* set comment on object through the VOL */
-    if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_OBJECT_SET_COMMENT, H5_REQUEST_NULL, comment) < 0)
+    if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_OBJECT_SET_COMMENT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, comment) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to set comment value")
 
 done:
@@ -851,7 +851,7 @@ H5Gget_comment(hid_t loc_id, const char *name, size_t bufsize, char *buf)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_GET_COMMENT, H5_REQUEST_NULL, 
+    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_GET_COMMENT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                        buf, bufsize, &size) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get object comment")
 
diff --git a/src/H5I.c b/src/H5I.c
index 115ef59..ed21277 100644
--- a/src/H5I.c
+++ b/src/H5I.c
@@ -2384,7 +2384,7 @@ H5Iget_file_id(hid_t obj_id)
         }
 
         /* Get the file through the VOL */
-        if(H5VL_file_get(obj, vol_plugin, H5VL_OBJECT_GET_FILE, H5_REQUEST_NULL, type, &file) < 0)
+        if(H5VL_file_get(obj, vol_plugin, H5VL_OBJECT_GET_FILE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, type, &file) < 0)
             HGOTO_ERROR(H5E_INTERNAL, H5E_CANTINIT, FAIL, "unable to get file")
 
         if (NULL == file)
diff --git a/src/H5L.c b/src/H5L.c
index f795d07..8d5f0aa 100644
--- a/src/H5L.c
+++ b/src/H5L.c
@@ -330,7 +330,7 @@ H5Lmove(hid_t src_loc_id, const char *src_name, hid_t dst_loc_id,
     /* Move the link through the VOL */
     if((ret_value = H5VL_link_move(obj1, loc_params1, obj2, loc_params2, 
                                    (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2), 
-                                   FALSE, lcpl_id, lapl_id, H5_REQUEST_NULL)) < 0)
+                                   FALSE, lcpl_id, lapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -421,7 +421,7 @@ H5Lcopy(hid_t src_loc_id, const char *src_name, hid_t dst_loc_id,
     /* Move the link through the VOL */
     if((ret_value = H5VL_link_move(obj1, loc_params1, obj2, loc_params2, 
                                    (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2), 
-                                   TRUE, lcpl_id, lapl_id, H5_REQUEST_NULL)) < 0)
+                                   TRUE, lcpl_id, lapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 done:
     FUNC_LEAVE_API(ret_value)
@@ -498,7 +498,7 @@ H5Lcreate_soft(const char *link_target,
 
     /* Create the link through the VOL */
     if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_SOFT, obj, loc_params, vol_plugin,
-                                     lcpl_id, lapl_id, H5_REQUEST_NULL)) < 0)
+                                     lcpl_id, lapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -601,7 +601,7 @@ H5Lcreate_hard(hid_t cur_loc_id, const char *cur_name,
     /* Create the link through the VOL */
     if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_HARD, obj2, loc_params2, 
                                      (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2),
-                                     lcpl_id, lapl_id, H5_REQUEST_NULL)) < 0)
+                                     lcpl_id, lapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -686,7 +686,7 @@ H5Lcreate_ud(hid_t link_loc_id, const char *link_name, H5L_type_t link_type,
 
     /* Create the link through the VOL */
     if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_UD, obj, loc_params, vol_plugin,
-                                     lcpl_id, lapl_id, H5_REQUEST_NULL)) < 0)
+                                     lcpl_id, lapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -739,7 +739,7 @@ H5Ldelete(hid_t loc_id, const char *name, hid_t lapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Delete the link through the VOL */
-    if((ret_value = H5VL_link_remove(obj, loc_params, vol_plugin, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_link_remove(obj, loc_params, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -807,7 +807,7 @@ H5Ldelete_by_idx(hid_t loc_id, const char *group_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Delete the link through the VOL */
-    if((ret_value = H5VL_link_remove(obj, loc_params, vol_plugin, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_link_remove(obj, loc_params, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -869,7 +869,7 @@ H5Lget_val(hid_t loc_id, const char *name, void *buf/*out*/, size_t size,
 
     /* Get the link info through the VOL */
     if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_VAL, 
-                                  H5_REQUEST_NULL, buf, size)) < 0)
+                                  H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, buf, size)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link value")
 
 done:
@@ -939,7 +939,7 @@ H5Lget_val_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type,
 
     /* Get the link info through the VOL */
     if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_VAL, 
-                                  H5_REQUEST_NULL, buf, size)) < 0)
+                                  H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, buf, size)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link value")
 
 done:
@@ -993,7 +993,7 @@ H5Lexists(hid_t loc_id, const char *name, hid_t lapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* check link existence through the VOL */
-    if(H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_EXISTS, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_EXISTS, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link info")
 
 done:
@@ -1049,7 +1049,7 @@ H5Lget_info(hid_t loc_id, const char *name, H5L_info_t *linfo /*out*/,
 
     /* Get the link info through the VOL */
     if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_INFO, 
-                                  H5_REQUEST_NULL, linfo)) < 0)
+                                  H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, linfo)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
 done:
@@ -1114,7 +1114,7 @@ H5Lget_info_by_idx(hid_t loc_id, const char *group_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the link info through the VOL */
-    if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_INFO, H5_REQUEST_NULL, 
+    if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_INFO, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                                   linfo)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -1310,7 +1310,7 @@ H5Lget_name_by_idx(hid_t loc_id, const char *group_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the link info through the VOL */
-    if((H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_NAME, H5_REQUEST_NULL, 
+    if((H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_NAME, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                       name, size, &ret_value)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link name")
 
@@ -1377,7 +1377,7 @@ H5Literate(hid_t id, H5_index_t idx_type, H5_iter_order_t order,
 
     /* iterate over the links through the VOL */
     if((ret_value = H5VL_link_iterate(obj, loc_params, vol_plugin, FALSE, idx_type, order, idx_p,
-                                      op, op_data, H5_REQUEST_NULL)) < 0)
+                                      op, op_data, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link iteration failed")
 
 done:
@@ -1450,7 +1450,7 @@ H5Literate_by_name(hid_t loc_id, const char *group_name,
 
     /* iterate over the links through the VOL */
     if((ret_value = H5VL_link_iterate(obj, loc_params, vol_plugin, FALSE, idx_type, order, idx_p,
-                                      op, op_data, H5_REQUEST_NULL)) < 0)
+                                      op, op_data, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link iteration failed")
 
 done:
@@ -1523,7 +1523,7 @@ H5Lvisit(hid_t grp_id, H5_index_t idx_type, H5_iter_order_t order,
 
     /* iterate over the links through the VOL */
     if((ret_value = H5VL_link_iterate(obj, loc_params, vol_plugin, TRUE, idx_type, order, NULL,
-                                      op, op_data, H5_REQUEST_NULL)) < 0)
+                                      op, op_data, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link iteration failed")
 
 done:
@@ -1601,7 +1601,7 @@ H5Lvisit_by_name(hid_t loc_id, const char *group_name, H5_index_t idx_type,
 
     /* visit the links through the VOL */
     if((ret_value = H5VL_link_iterate(obj, loc_params, vol_plugin, TRUE, idx_type, order, NULL,
-                                      op, op_data, H5_REQUEST_NULL)) < 0)
+                                      op, op_data, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link iteration failed")
 
 done:
diff --git a/src/H5Lexternal.c b/src/H5Lexternal.c
index 0739daf..847731b 100644
--- a/src/H5Lexternal.c
+++ b/src/H5Lexternal.c
@@ -630,7 +630,7 @@ H5Lcreate_external(const char *file_name, const char *obj_name,
 
     /* Create the link through the VOL */
     if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_UD, obj, loc_params, vol_plugin,
-                                     lcpl_id, lapl_id, H5_REQUEST_NULL)) < 0)
+                                     lcpl_id, lapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
diff --git a/src/H5O.c b/src/H5O.c
index e95831f..5794e6f 100644
--- a/src/H5O.c
+++ b/src/H5O.c
@@ -255,7 +255,7 @@ H5Oopen(hid_t loc_id, const char *name, hid_t lapl_id)
 
     /* Open the object through the VOL */
     if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, 
-                                              H5_REQUEST_NULL)))
+                                              H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open object")
 
     if ((ret_value = H5VL_object_register(opened_obj, opened_type, vol_plugin, TRUE)) < 0)
@@ -332,7 +332,7 @@ H5Oopen_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Open the object through the VOL */
-    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, H5_REQUEST_NULL)))
+    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open object")
 
     if ((ret_value = H5VL_object_register(opened_obj, opened_type, vol_plugin, TRUE)) < 0)
@@ -403,7 +403,7 @@ H5Oopen_by_addr(hid_t loc_id, haddr_t addr)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Open the object through the VOL */
-    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, H5_REQUEST_NULL)))
+    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open object")
 
     if ((ret_value = H5VL_object_register(opened_obj, opened_type, vol_plugin, TRUE)) < 0)
@@ -511,7 +511,7 @@ H5Olink(hid_t obj_id, hid_t new_loc_id, const char *new_name, hid_t lcpl_id,
     /* Create the link through the VOL */
     if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_HARD, obj2, loc_params2, 
                                      (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2),
-                                     lcpl_id, lapl_id, H5_REQUEST_NULL)) < 0)
+                                     lcpl_id, lapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -562,7 +562,7 @@ H5Oincr_refcount(hid_t object_id)
 
     /* change the ref count through the VOL */
     if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_OBJECT_CHANGE_REF_COUNT, 
-                        H5_REQUEST_NULL, 1) < 0)
+                        H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 1) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "modifying object link count failed")
 
 done:
@@ -612,7 +612,7 @@ H5Odecr_refcount(hid_t object_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* change the ref count through the VOL */
-    if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_OBJECT_CHANGE_REF_COUNT, H5_REQUEST_NULL, -1) < 0)
+    if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_OBJECT_CHANGE_REF_COUNT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, -1) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "modifying object link count failed")
 
 done:
@@ -666,7 +666,7 @@ H5Oexists_by_name(hid_t loc_id, const char *name, hid_t lapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* change the ref count through the VOL */
-    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_EXISTS, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_EXISTS, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "unable to determine if '%s' exists", name)
 
 done:
@@ -714,7 +714,7 @@ H5Oget_info(hid_t loc_id, H5O_info_t *oinfo)
 
     /* Get the group info through the VOL using the location token */
     if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_GET_INFO, 
-                                    H5_REQUEST_NULL, oinfo)) < 0)
+                                    H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, oinfo)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
 done:
@@ -772,7 +772,7 @@ H5Oget_info_by_name(hid_t loc_id, const char *name, H5O_info_t *oinfo, hid_t lap
 
     /* Get the group info through the VOL using the location token */
     if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_GET_INFO, 
-                                    H5_REQUEST_NULL, oinfo)) < 0)
+                                    H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, oinfo)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
 done:
@@ -839,7 +839,7 @@ H5Oget_info_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type,
 
     /* Get the group info through the VOL using the location token */
     if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_GET_INFO, 
-                                    H5_REQUEST_NULL, oinfo)) < 0)
+                                    H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, oinfo)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
 done:
@@ -886,7 +886,7 @@ H5Oset_comment(hid_t obj_id, const char *comment)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* set comment on object through the VOL */
-    if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_OBJECT_SET_COMMENT, H5_REQUEST_NULL, comment) < 0)
+    if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_OBJECT_SET_COMMENT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, comment) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to set comment value")
 
 done:
@@ -945,7 +945,7 @@ H5Oset_comment_by_name(hid_t loc_id, const char *name, const char *comment,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* set comment on object through the VOL */
-    if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_OBJECT_SET_COMMENT, H5_REQUEST_NULL, comment) < 0)
+    if(H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_OBJECT_SET_COMMENT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, comment) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to set comment value")
 
 done:
@@ -990,7 +990,7 @@ H5Oget_comment(hid_t loc_id, char *comment, size_t bufsize)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_GET_COMMENT, H5_REQUEST_NULL, 
+    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_GET_COMMENT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                        comment, bufsize, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get object comment")
 
@@ -1048,7 +1048,7 @@ H5Oget_comment_by_name(hid_t loc_id, const char *name, char *comment, size_t buf
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_GET_COMMENT, H5_REQUEST_NULL, 
+    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_OBJECT_GET_COMMENT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                        comment, bufsize, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get object info")
 
@@ -1121,7 +1121,7 @@ H5Ovisit(hid_t obj_id, H5_index_t idx_type, H5_iter_order_t order,
 
     /* iterate over the objects through the VOL */
     if((ret_value = H5VL_object_visit(obj, loc_params, vol_plugin, idx_type, order, op, op_data, 
-                                      H5_REQUEST_NULL)) < 0)
+                                      H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link iteration failed")
 
 done:
@@ -1203,7 +1203,7 @@ H5Ovisit_by_name(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
 
     /* iterate over the objects through the VOL */
     if((ret_value = H5VL_object_visit(obj, loc_params, vol_plugin, idx_type, order, op, 
-                                      op_data, H5_REQUEST_NULL)) < 0)
+                                      op_data, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link iteration failed")
 
 done:
@@ -1268,7 +1268,7 @@ H5Oclose(hid_t object_id)
 
 #if 0
     /* Close the object through the VOL */
-    if(H5VL_object_close(object_id, H5_REQUEST_NULL) < 0)
+    if(H5VL_object_close(object_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTRELEASE, FAIL, "unable to close object")
 #endif
 
diff --git a/src/H5Ocopy.c b/src/H5Ocopy.c
index 597c7e1..85346eb 100644
--- a/src/H5Ocopy.c
+++ b/src/H5Ocopy.c
@@ -254,7 +254,7 @@ H5Ocopy(hid_t src_loc_id, const char *src_name, hid_t dst_loc_id,
     /* Open the object through the VOL */
     if((ret_value = H5VL_object_copy(obj1, loc_params1, vol_plugin1, src_name, 
                                      obj2, loc_params2, vol_plugin2, dst_name, 
-                                     ocpypl_id, lcpl_id, H5_REQUEST_NULL)) < 0)
+                                     ocpypl_id, lcpl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open object")
 done:
     FUNC_LEAVE_API(ret_value)
diff --git a/src/H5R.c b/src/H5R.c
index 90d28ac..9a43563 100644
--- a/src/H5R.c
+++ b/src/H5R.c
@@ -374,7 +374,7 @@ H5Rcreate(void *ref, hid_t loc_id, const char *name, H5R_type_t ref_type, hid_t
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* create the ref through the VOL */
-    if(ret_value = H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_REF_CREATE, H5_REQUEST_NULL, 
+    if(ret_value = H5VL_object_misc(obj, loc_params, vol_plugin, H5VL_REF_CREATE, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                                     ref, name, ref_type, space_id) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "modifying object link count failed")
 
@@ -602,7 +602,7 @@ H5Rdereference2(hid_t obj_id, hid_t oapl_id, H5R_type_t ref_type, const void *_r
     loc_params.obj_type = H5I_get_type(obj_id);
 
     /* Open the object through the VOL */
-    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, H5_REQUEST_NULL)))
+    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open object")
 
     /* Get an atom for the object */
@@ -734,7 +734,7 @@ H5Rget_region(hid_t id, H5R_type_t ref_type, const void *ref)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the space id through the VOL */
-    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_REF_GET_REGION, H5_REQUEST_NULL, 
+    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_REF_GET_REGION, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                        &ret_value, ref_type, ref) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -882,7 +882,7 @@ H5Rget_obj_type2(hid_t id, H5R_type_t ref_type, const void *ref,
 
     /* get the object type through the VOL */
     if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, H5VL_REF_GET_TYPE, 
-                                    H5_REQUEST_NULL, obj_type, ref_type, ref)) < 0)
+                                    H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, obj_type, ref_type, ref)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
 done:
@@ -1049,7 +1049,7 @@ H5Rget_name(hid_t id, H5R_type_t ref_type, const void *_ref, char *name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* get the object type through the VOL */
-    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_REF_GET_NAME, H5_REQUEST_NULL, 
+    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_REF_GET_NAME, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, 
                        &ret_value, name, size, ref_type, _ref) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 done:
diff --git a/src/H5Rdeprec.c b/src/H5Rdeprec.c
index 8933ed5..c2aa6ea 100644
--- a/src/H5Rdeprec.c
+++ b/src/H5Rdeprec.c
@@ -161,7 +161,7 @@ H5Rget_obj_type1(hid_t id, H5R_type_t ref_type, const void *ref)
 
     /* get the object type through the VOL */
     if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, H5VL_REF_GET_TYPE,
-                                    H5_REQUEST_NULL, &obj_type, ref_type, ref)) < 0)
+                                    H5AC_dxpl_id, H5_EVENT_QUEUE_NULL, &obj_type, ref_type, ref)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
     /* Set return value */
@@ -227,7 +227,7 @@ H5Rdereference1(hid_t obj_id, H5R_type_t ref_type, const void *_ref)
     loc_params.obj_type = H5I_get_type(obj_id);
 
     /* Open the object through the VOL */
-    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, H5_REQUEST_NULL)))
+    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open object")
 
     /* Get an atom for the object */
diff --git a/src/H5Tcommit.c b/src/H5Tcommit.c
index 9d02c72..6c1dbb5 100644
--- a/src/H5Tcommit.c
+++ b/src/H5Tcommit.c
@@ -175,7 +175,7 @@ H5Tcommit2(hid_t loc_id, const char *name, hid_t type_id, hid_t lcpl_id,
 
     /* commit the datatype through the VOL */
     if (NULL == (dt = H5VL_datatype_commit(obj, loc_params, vol_plugin, name, type_id, lcpl_id, 
-                                           tcpl_id, tapl_id, H5_REQUEST_NULL)))
+                                           tcpl_id, tapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to commit datatype")
 
     /* attach the vol object created using the commit call to the 
@@ -336,7 +336,7 @@ H5Tcommit_anon(hid_t loc_id, hid_t type_id, hid_t tcpl_id, hid_t tapl_id)
 
     /* commite the datatype through the VOL */
     if (NULL == (dt = H5VL_datatype_commit(obj, loc_params, vol_plugin, NULL, type_id, H5P_DEFAULT, 
-                                           tcpl_id, tapl_id, H5_REQUEST_NULL)))
+                                           tcpl_id, tapl_id, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to commit datatype")
 
     /* attach the vol object created using the commit call to the 
@@ -624,16 +624,17 @@ H5Topen2(hid_t loc_id, const char *name, hid_t tapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the datatype through the VOL */
-    if(NULL == (dt = H5VL_datatype_open(obj, loc_params, vol_plugin, name, tapl_id, H5_REQUEST_NULL)))
+    if(NULL == (dt = H5VL_datatype_open(obj, loc_params, vol_plugin, name, tapl_id, 
+                                        H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open datatype")
 
     /* Get an atom for the datatype */
-    if ((ret_value = H5VL_create_datatype(dt, vol_plugin, TRUE, H5_REQUEST_NULL)) < 0)
+    if ((ret_value = H5VL_create_datatype(dt, vol_plugin, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize datatype handle")
 
 done:
     if (ret_value < 0 && dt)
-        if(H5VL_datatype_close (dt, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_datatype_close (dt, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Topen2() */
@@ -956,7 +957,7 @@ H5T_get_named_type(const H5T_t *dt)
  *-------------------------------------------------------------------------
  */
 hid_t
-H5VL_create_datatype(void *dt_obj, H5VL_t *vol_plugin, hbool_t app_ref, hid_t req)
+H5VL_create_datatype(void *dt_obj, H5VL_t *vol_plugin, hbool_t app_ref)
 {
     ssize_t        nalloc;
     unsigned char *buf = NULL;
@@ -965,8 +966,9 @@ H5VL_create_datatype(void *dt_obj, H5VL_t *vol_plugin, hbool_t app_ref, hid_t re
 
     FUNC_ENTER_NOAPI(FAIL)
 
-   /* get required buf size for encoding the datatype */
-   if((nalloc = H5VL_datatype_get_binary(dt_obj, vol_plugin, NULL, 0, req)) < 0)
+    /* get required buf size for encoding the datatype */
+    if((nalloc = H5VL_datatype_get_binary(dt_obj, vol_plugin, NULL, 0, 
+                                          H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to get datatype size")
 
     /* allocate buffer to store binary description of the datatype */
@@ -974,7 +976,8 @@ H5VL_create_datatype(void *dt_obj, H5VL_t *vol_plugin, hbool_t app_ref, hid_t re
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate space for datatype")
 
     /* get binary description of the datatype */
-    if((nalloc = H5VL_datatype_get_binary(dt_obj, vol_plugin, buf, (size_t) nalloc, req)) < 0)
+    if((nalloc = H5VL_datatype_get_binary(dt_obj, vol_plugin, buf, (size_t) nalloc, 
+                                          H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to get datatype size")
 
     if(NULL == (dt = H5T_decode(buf)))
@@ -1016,7 +1019,7 @@ H5T_close_datatype(void *type, H5VL_t *vol_plugin)
 
     /* Close the datatype through the VOL*/
     if (NULL != dt->vol_obj)
-        if((ret_value = H5VL_datatype_close(dt->vol_obj, vol_plugin, H5_REQUEST_NULL)) < 0)
+        if((ret_value = H5VL_datatype_close(dt->vol_obj, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
             HGOTO_ERROR(H5E_DATATYPE, H5E_CLOSEERROR, FAIL, "unable to close datatype")
 
 done:
diff --git a/src/H5Tdeprec.c b/src/H5Tdeprec.c
index b59591a..dbdb8ea 100644
--- a/src/H5Tdeprec.c
+++ b/src/H5Tdeprec.c
@@ -156,7 +156,7 @@ H5Tcommit1(hid_t loc_id, const char *name, hid_t type_id)
     /* commit the datatype through the VOL */
     if (NULL == (dt = H5VL_datatype_commit(obj, loc_params, vol_plugin, name, type_id, 
                                            H5P_LINK_CREATE_DEFAULT, H5P_DATATYPE_CREATE_DEFAULT, 
-                                           H5P_DATATYPE_ACCESS_DEFAULT, H5_REQUEST_NULL)))
+                                           H5P_DATATYPE_ACCESS_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to commit datatype")
 
     /* attach the vol object created using the commit call to the 
@@ -217,16 +217,16 @@ H5Topen1(hid_t loc_id, const char *name)
 
     /* Create the datatype through the VOL */
     if(NULL == (dt = H5VL_datatype_open(obj, loc_params, vol_plugin, name, 
-                                        H5P_DATATYPE_ACCESS_DEFAULT, H5_REQUEST_NULL)))
+                                        H5P_DATATYPE_ACCESS_DEFAULT, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open datatype")
 
     /* Get an atom for the datatype */
-    if ((ret_value = H5VL_create_datatype(dt, vol_plugin, TRUE, H5_REQUEST_NULL)) < 0)
+    if ((ret_value = H5VL_create_datatype(dt, vol_plugin, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize datatype handle")
 
 done:
     if (ret_value < 0 && dt)
-        if(H5VL_datatype_close (dt, vol_plugin, H5_REQUEST_NULL) < 0)
+        if(H5VL_datatype_close (dt, vol_plugin, H5AC_dxpl_id, H5_EVENT_QUEUE_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Topen1() */
diff --git a/src/H5Tprivate.h b/src/H5Tprivate.h
index 7a48bd5..217a0d6 100644
--- a/src/H5Tprivate.h
+++ b/src/H5Tprivate.h
@@ -141,7 +141,7 @@ H5_DLL herr_t H5T_set_latest_version(H5T_t *dt);
 H5_DLL herr_t H5T_patch_file(H5T_t *dt, H5F_t *f);
 H5_DLL htri_t H5T_is_variable_str(const H5T_t *dt);
 H5_DLL void * H5T_get_named_type(const H5T_t *dt);
-H5_DLL hid_t H5VL_create_datatype(void *dt_obj, H5VL_t *vol_plugin, hbool_t app_ref, hid_t req);
+H5_DLL hid_t H5VL_create_datatype(void *dt_obj, H5VL_t *vol_plugin, hbool_t app_ref);
 H5_DLL herr_t H5T_set_vol_object(H5T_t *type, void *vol_obj);
 
 /* Reference specific functions */
diff --git a/src/H5VL.c b/src/H5VL.c
index 9c42f99..74760d4 100644
--- a/src/H5VL.c
+++ b/src/H5VL.c
@@ -108,7 +108,7 @@ done:
 static herr_t
 H5VL_init_interface(void)
 {
-    herr_t      ret_value = SUCCEED;       /* Return value */
+    herr_t ret_value = SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT
 
@@ -227,7 +227,7 @@ done:
 hid_t
 H5VLregister(const H5VL_class_t *cls)
 {
-    hid_t		ret_value;
+    hid_t ret_value;
 
     FUNC_ENTER_API(FAIL)
     H5TRACE1("i", "*x", cls);
@@ -266,7 +266,7 @@ done:
 herr_t
 H5VLunregister(hid_t vol_id)
 {
-    herr_t      ret_value = SUCCEED;       /* Return value */
+    herr_t ret_value = SUCCEED;       /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE1("e", "i", vol_id);
@@ -395,7 +395,7 @@ done:
  */
 void *
 H5VLattr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                hid_t acpl_id, hid_t aapl_id, hid_t req)
+                hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     void *ret_value = NULL;  /* Return value */
 
@@ -403,7 +403,7 @@ H5VLattr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, con
 
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_attr_create(obj, loc_params, vol_plugin, name, acpl_id, aapl_id, req)))
+    if(NULL == (ret_value = H5VL_attr_create(obj, loc_params, vol_plugin, name, acpl_id, aapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create attribute")
 
 done:
@@ -427,7 +427,7 @@ done:
  */
 void *
 H5VLattr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-              hid_t aapl_id, hid_t req)
+              hid_t aapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     void *ret_value;  /* Return value */
 
@@ -435,7 +435,7 @@ H5VLattr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const
 
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_attr_open(obj, loc_params, vol_plugin, name, aapl_id, req)))
+    if(NULL == (ret_value = H5VL_attr_open(obj, loc_params, vol_plugin, name, aapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to open attribute")
 
 done:
@@ -457,15 +457,15 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VLattr_read(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, void *buf, hid_t req)
+herr_t H5VLattr_read(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, void *buf, hid_t dxpl_id, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if (NULL == attr || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_attr_read(attr, vol_plugin, mem_type_id, buf, req)) < 0)
+    if((ret_value = H5VL_attr_read(attr, vol_plugin, mem_type_id, buf, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to read attribute")
 
 done:
@@ -487,15 +487,15 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VLattr_write(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, const void *buf, hid_t req)
+herr_t H5VLattr_write(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, const void *buf, hid_t dxpl_id, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if (NULL == attr || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_attr_write(attr, vol_plugin, mem_type_id, buf, req)) < 0)
+    if((ret_value = H5VL_attr_write(attr, vol_plugin, mem_type_id, buf, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to write attribute")
 
 done:
@@ -518,7 +518,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLattr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req, va_list arguments)
+H5VLattr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -535,7 +535,7 @@ H5VLattr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req,
                 char    *attr_name      = va_arg (arguments, char *);
                 htri_t	*ret       = va_arg (arguments, htri_t *);
 
-                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, req, 
+                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, 
                                               loc_params, attr_name, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get attribute information")
                 break;
@@ -545,7 +545,7 @@ H5VLattr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req,
             {
                 hid_t	*ret_id = va_arg (arguments, hid_t *);
 
-                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, req, ret_id)) < 0)
+                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get attribute information")
                 break;
             }
@@ -554,7 +554,7 @@ H5VLattr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req,
             {
                 hid_t	*ret_id = va_arg (arguments, hid_t *);
 
-                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, req, ret_id)) < 0)
+                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get attribute information")
                 break;
             }
@@ -563,7 +563,7 @@ H5VLattr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req,
             {
                 hid_t	*ret_id = va_arg (arguments, hid_t *);
 
-                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, req, ret_id)) < 0)
+                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get attribute information")
                 break;
             }
@@ -575,7 +575,7 @@ H5VLattr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req,
                 char    *buf = va_arg (arguments, char *);
                 ssize_t	*ret_val = va_arg (arguments, ssize_t *);
 
-                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, req, 
+                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, 
                                               loc_params, buf_size, buf, ret_val)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get attribute information")
                 break;
@@ -587,17 +587,17 @@ H5VLattr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req,
                 H5A_info_t   *ainfo = va_arg (arguments, H5A_info_t *);
 
                 if(H5VL_OBJECT_BY_SELF == loc_params.type) {
-                    if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, req, loc_params, ainfo)) < 0)
+                    if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, loc_params, ainfo)) < 0)
                         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get attribute information")
                 }
                 else if(H5VL_OBJECT_BY_NAME == loc_params.type) {
                     char *attr_name = va_arg (arguments, char *);
 
-                    if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, req, loc_params, ainfo, attr_name)) < 0)
+                    if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, loc_params, ainfo, attr_name)) < 0)
                         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get attribute information")
                 }
                 else if(H5VL_OBJECT_BY_IDX == loc_params.type) {
-                    if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, req, loc_params, ainfo)) < 0)
+                    if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, loc_params, ainfo)) < 0)
                         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get attribute information")
                 }
                 else
@@ -608,7 +608,7 @@ H5VLattr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req,
         case H5VL_ATTR_GET_STORAGE_SIZE:
             {
                 hsize_t *ret = va_arg (arguments, hsize_t *);
-                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, req, ret)) < 0)
+                if((ret_value = H5VL_attr_get(obj, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get attribute information")
                 break;
             }
@@ -637,15 +637,15 @@ done:
  */
 herr_t 
 H5VLattr_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
-                 const char *attr_name, hid_t req)
+                 const char *attr_name, hid_t dxpl_id, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_attr_remove(obj, loc_params, vol_plugin, attr_name, req)) < 0)
+    if((ret_value = H5VL_attr_remove(obj, loc_params, vol_plugin, attr_name, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to remove attribute")
 
 done:
@@ -668,15 +668,15 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLattr_close(void *attr, H5VL_t *vol_plugin, hid_t req)
+H5VLattr_close(void *attr, H5VL_t *vol_plugin, hid_t dxpl_id, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if (NULL == attr || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_attr_close(attr, vol_plugin, req)) < 0)
+    if((ret_value = H5VL_attr_close(attr, vol_plugin, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to close attribute")
 
 done:
@@ -700,7 +700,7 @@ done:
  */
 void *
 H5VLdatatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                     hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t req)
+                     hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     void *ret_value = NULL;              /* Return value */
 
@@ -709,7 +709,7 @@ H5VLdatatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
     if(NULL == (ret_value = H5VL_datatype_commit(obj, loc_params, vol_plugin, name, type_id, 
-                                                 lcpl_id, tcpl_id, tapl_id, req)))
+                                                 lcpl_id, tcpl_id, tapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to commit datatype")
 
 done:
@@ -733,7 +733,7 @@ done:
  */
 void *
 H5VLdatatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                   hid_t tapl_id, hid_t req)
+                   hid_t tapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     void *ret_value = NULL;              /* Return value */
 
@@ -741,7 +741,7 @@ H5VLdatatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, c
 
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_datatype_open(obj, loc_params, vol_plugin, name, tapl_id, req)))
+    if(NULL == (ret_value = H5VL_datatype_open(obj, loc_params, vol_plugin, name, tapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to open datatype")
 
 done:
@@ -764,7 +764,7 @@ done:
  *-------------------------------------------------------------------------
  */
 ssize_t 
-H5VLdatatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size_t size, hid_t req)
+H5VLdatatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size_t size, hid_t dxpl_id, void UNUSED **req)
 {
     ssize_t ret_value = FAIL;
 
@@ -772,7 +772,7 @@ H5VLdatatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size_
 
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_datatype_get_binary(obj, vol_plugin, buf, size, req)) < 0)
+    if((ret_value = H5VL_datatype_get_binary(obj, vol_plugin, buf, size, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to encode datatype")
 
 done:
@@ -794,7 +794,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdatatype_close(void *dt, H5VL_t *vol_plugin, hid_t req)
+H5VLdatatype_close(void *dt, H5VL_t *vol_plugin, hid_t dxpl_id, void UNUSED **req)
 {
     herr_t		ret_value = SUCCEED;    /* Return value */
 
@@ -802,7 +802,7 @@ H5VLdatatype_close(void *dt, H5VL_t *vol_plugin, hid_t req)
 
     if (NULL == dt || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_datatype_close(dt, vol_plugin, req)) < 0)
+    if((ret_value = H5VL_datatype_close(dt, vol_plugin, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to close datatype")
 
 done:
@@ -826,7 +826,7 @@ done:
  */
 void *
 H5VLdataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                    hid_t dcpl_id, hid_t dapl_id, hid_t req)
+                    hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     void *ret_value; /* Return value */
 
@@ -835,7 +835,7 @@ H5VLdataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
     if(NULL == (ret_value = H5VL_dataset_create(obj, loc_params, vol_plugin, name, 
-                                                dcpl_id, dapl_id, req)))
+                                                dcpl_id, dapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create dataset")
 
 done:
@@ -859,7 +859,7 @@ done:
  */
 void *
 H5VLdataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                  hid_t dapl_id, hid_t req)
+                  hid_t dapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     void *ret_value; /* Return value */
 
@@ -867,7 +867,7 @@ H5VLdataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, co
 
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_dataset_open(obj, loc_params, vol_plugin, name, dapl_id, req)))
+    if(NULL == (ret_value = H5VL_dataset_open(obj, loc_params, vol_plugin, name, dapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to open dataset")
 
 done:
@@ -891,16 +891,16 @@ done:
  */
 herr_t 
 H5VLdataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, 
-                  hid_t file_space_id, hid_t plist_id, void *buf, hid_t req)
+                  hid_t file_space_id, hid_t plist_id, void *buf, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if (NULL == dset || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
     if((ret_value = H5VL_dataset_read(dset, vol_plugin, mem_type_id, mem_space_id, file_space_id, 
-                                      plist_id, buf, req)) < 0)
+                                      plist_id, buf, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to read dataset")
 
 done:
@@ -924,16 +924,16 @@ done:
  */
 herr_t 
 H5VLdataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, 
-                   hid_t file_space_id, hid_t plist_id, const void *buf, hid_t req)
+                   hid_t file_space_id, hid_t plist_id, const void *buf, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if (NULL == dset || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
     if((ret_value = H5VL_dataset_write(dset, vol_plugin, mem_type_id, mem_space_id, file_space_id, 
-                                       plist_id, buf, req)) < 0)
+                                       plist_id, buf, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to write dataset")
 
 done:
@@ -956,15 +956,15 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t 
-H5VLdataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], hid_t req)
+H5VLdataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], hid_t dxpl_id, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if (NULL == dset || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_dataset_set_extent(dset, vol_plugin, size, req)) < 0)
+    if((ret_value = H5VL_dataset_set_extent(dset, vol_plugin, size, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to set extent of dataset")
 
 done:
@@ -987,7 +987,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid_t req, va_list arguments)
+H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid_t dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1002,7 +1002,7 @@ H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid
             {
                 hid_t	*ret_id = va_arg (arguments, hid_t *);
 
-                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, req, ret_id)) < 0)
+                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get dataset information")
                 break;
             }
@@ -1011,7 +1011,7 @@ H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid
             {
                 H5D_space_status_t *allocation = va_arg (arguments, H5D_space_status_t *);
 
-                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, req, allocation)) < 0)
+                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, allocation)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get dataset information")
                 break;
             }
@@ -1020,7 +1020,7 @@ H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid
             {
                 hid_t	*ret_id = va_arg (arguments, hid_t *);
 
-                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, req, ret_id)) < 0)
+                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get dataset information")
                 break;
             }
@@ -1029,7 +1029,7 @@ H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid
             {
                 hid_t	*ret_id = va_arg (arguments, hid_t *);
 
-                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, req, ret_id)) < 0)
+                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get dataset information")
                 break;
             }
@@ -1038,7 +1038,7 @@ H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid
             {
                 hid_t	*ret_id = va_arg (arguments, hid_t *);
 
-                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, req, ret_id)) < 0)
+                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get dataset information")
                 break;
             }
@@ -1047,7 +1047,7 @@ H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid
             {
                 hsize_t *ret = va_arg (arguments, hsize_t *);
 
-                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, req, ret)) < 0)
+                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get dataset information")
                 break;
             }
@@ -1056,7 +1056,7 @@ H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid
             {
                 haddr_t *ret = va_arg (arguments, haddr_t *);
 
-                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, req, ret)) < 0)
+                if((ret_value = H5VL_dataset_get(dset, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get dataset information")
                 break;
             }
@@ -1084,15 +1084,15 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdataset_close(void *dset, H5VL_t *vol_plugin, hid_t req)
+H5VLdataset_close(void *dset, H5VL_t *vol_plugin, hid_t dxpl_id, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if (NULL == dset || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_dataset_close(dset, vol_plugin, req)) < 0)
+    if((ret_value = H5VL_dataset_close(dset, vol_plugin, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to close dataset")
 
 done:
@@ -1116,13 +1116,13 @@ done:
  */
 void *
 H5VLfile_create(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fcpl_id, 
-                hid_t fapl_id, hid_t req)
+                hid_t fapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     void	       *ret_value;             /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if(NULL == (ret_value = H5VL_file_create(vol_plugin, name, flags, fcpl_id, fapl_id, req)))
+    if(NULL == (ret_value = H5VL_file_create(vol_plugin, name, flags, fcpl_id, fapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create file")
 
 done:
@@ -1145,13 +1145,13 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLfile_open(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fapl_id, hid_t req)
+H5VLfile_open(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     void	       *ret_value;             /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if(NULL == (ret_value = H5VL_file_open(vol_plugin, name, flags, fapl_id, req)))
+    if(NULL == (ret_value = H5VL_file_open(vol_plugin, name, flags, fapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create file")
 
 done:
@@ -1175,15 +1175,15 @@ done:
  */
 herr_t
 H5VLfile_flush(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
-               H5F_scope_t scope, hid_t req)
+               H5F_scope_t scope, hid_t dxpl_id, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_file_flush(obj, loc_params, vol_plugin, scope, req)) < 0)
+    if((ret_value = H5VL_file_flush(obj, loc_params, vol_plugin, scope, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to flush file")
 
 done:
@@ -1206,7 +1206,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req, va_list arguments)
+H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1221,7 +1221,7 @@ H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req
             {
                 hid_t *plist_id = va_arg (arguments, hid_t *);
 
-                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, req, plist_id)) < 0)
+                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, plist_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get file information")
                 break;
             }
@@ -1230,7 +1230,7 @@ H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req
             {
                 hid_t *plist_id = va_arg (arguments, hid_t *);
 
-                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, req, plist_id)) < 0)
+                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, plist_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get file information")
                 break;
             }
@@ -1240,7 +1240,7 @@ H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req
                 unsigned types = va_arg (arguments, unsigned);
                 ssize_t *ret = va_arg (arguments, ssize_t *);
 
-                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, req, types, ret)) < 0)
+                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, types, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get file information")
                 break;
             }
@@ -1252,7 +1252,7 @@ H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req
                 hid_t *oid_list = va_arg (arguments, hid_t *);
                 ssize_t *ret = va_arg (arguments, ssize_t *);
 
-                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, req, types, max_objs, 
+                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, types, max_objs, 
                                               oid_list, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get file information")
                 break;
@@ -1262,7 +1262,7 @@ H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req
             {
                 unsigned *ret = va_arg (arguments, unsigned *);
 
-                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, req, ret)) < 0)
+                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get file information")
                 break;
             }
@@ -1274,7 +1274,7 @@ H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req
                 char      *name = va_arg (arguments, char *);
                 ssize_t   *ret  = va_arg (arguments, ssize_t *);
 
-                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, req, type, size, 
+                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, type, size, 
                                               name, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get file information")
                 break;
@@ -1285,7 +1285,7 @@ H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req
                 H5I_type_t type = va_arg (arguments, H5I_type_t);
                 void      **ret = va_arg (arguments, void **);
 
-                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, req, type, ret)) < 0)
+                if((ret_value = H5VL_file_get(file, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, type, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get file information")
                 break;
             }
@@ -1312,7 +1312,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLfile_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t req, va_list arguments)
+H5VLfile_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1330,7 +1330,7 @@ H5VLfile_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t
                 H5F_t      *child      = va_arg (arguments, H5F_t *);
                 hid_t       plist_id   = va_arg (arguments, hid_t);
 
-                if((ret_value = H5VL_file_misc(file, vol_plugin, misc_type, req, 
+                if((ret_value = H5VL_file_misc(file, vol_plugin, misc_type, dxpl_id, H5_EVENT_QUEUE_NULL, 
                                                type, name, child, plist_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
 
@@ -1342,7 +1342,7 @@ H5VLfile_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t
                 H5I_type_t  type       = va_arg (arguments, H5I_type_t);
                 const char *name       = va_arg (arguments, const char *);
 
-                if((ret_value = H5VL_file_misc(file, vol_plugin, misc_type, req, type, name)) < 0)
+                if((ret_value = H5VL_file_misc(file, vol_plugin, misc_type, dxpl_id, H5_EVENT_QUEUE_NULL, type, name)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
@@ -1353,7 +1353,7 @@ H5VLfile_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t
                 const char *name    = va_arg (arguments, const char *);
                 htri_t     *ret     = va_arg (arguments, htri_t *);
 
-                if((ret_value = H5VL_file_misc(file, vol_plugin, misc_type, req, fapl_id, name, ret)) < 0)
+                if((ret_value = H5VL_file_misc(file, vol_plugin, misc_type, dxpl_id, H5_EVENT_QUEUE_NULL, fapl_id, name, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
@@ -1380,7 +1380,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_type, hid_t req, va_list arguments)
+H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_type, hid_t dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1395,7 +1395,7 @@ H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_
             {
                 hsize_t    *ret = va_arg (arguments, hsize_t *);
 
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req, ret)) < 0)
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
@@ -1406,7 +1406,7 @@ H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_
                 ssize_t    *ret       = va_arg (arguments, ssize_t *);
                 size_t      buf_len   = va_arg (arguments, size_t );
 
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req, 
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL, 
                                                    buf_ptr, ret, buf_len)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
@@ -1416,7 +1416,7 @@ H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_
             {
                 hssize_t    *ret = va_arg (arguments, hssize_t *);
 
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req, ret)) < 0)
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
@@ -1427,7 +1427,7 @@ H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_
                 H5F_mem_t       type       = va_arg (arguments, H5F_mem_t);
                 size_t          nsects     = va_arg (arguments, size_t);
 
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req,
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL,
                                                    sect_info, ret, type, nsects)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
@@ -1438,7 +1438,7 @@ H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_
                 H5I_type_t  type   = va_arg (arguments, H5I_type_t);
                 H5F_info2_t *finfo = va_arg (arguments, H5F_info2_t *);
 
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req, type, finfo)) < 0)
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL, type, finfo)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
@@ -1447,7 +1447,7 @@ H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_
             {
                 H5AC_cache_config_t *config_ptr = va_arg (arguments, H5AC_cache_config_t *);
 
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req, config_ptr)) < 0)
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL, config_ptr)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
@@ -1456,7 +1456,7 @@ H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_
             {
                 double *hit_rate_ptr = va_arg (arguments, double *);
 
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req, hit_rate_ptr)) < 0)
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL, hit_rate_ptr)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
@@ -1468,7 +1468,7 @@ H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_
                 size_t *cur_size_ptr        = va_arg (arguments, size_t *); 
                 int    *cur_num_entries_ptr = va_arg (arguments, int *); 
 
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req, max_size_ptr, 
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL, max_size_ptr, 
                                                    min_clean_size_ptr, cur_size_ptr, cur_num_entries_ptr)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
@@ -1479,14 +1479,14 @@ H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_
                 void **file_handle = va_arg (arguments, void **);
                 hid_t  fapl        = va_arg (arguments, hid_t);
 
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req, file_handle, fapl)) < 0)
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL, file_handle, fapl)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
         /* H5Fclear_elink_file_cache */
         case H5VL_FILE_CLEAR_ELINK_CACHE:
             {
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req)) < 0)
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
@@ -1495,14 +1495,14 @@ H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_
             {
                 void   **ret = va_arg (arguments, void **);
 
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req, ret)) < 0)
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
         /* H5Freset_mdc_hit_rate_stats */
         case H5VL_FILE_RESET_MDC_HIT_RATE:
             {
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req)) < 0)
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
@@ -1510,7 +1510,7 @@ H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_
             {
                 H5AC_cache_config_t *config_ptr = va_arg (arguments, H5AC_cache_config_t *);
 
-                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, req, config_ptr)) < 0)
+                if((ret_value = H5VL_file_optional(file, vol_plugin, optional_type, dxpl_id, H5_EVENT_QUEUE_NULL, config_ptr)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to operate on the file")
                 break;
             }
@@ -1538,15 +1538,15 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLfile_close(void *file, H5VL_t *vol_plugin, hid_t req)
+H5VLfile_close(void *file, H5VL_t *vol_plugin, hid_t dxpl_id, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if(NULL == file || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_file_close(file, vol_plugin, req)) < 0)
+    if((ret_value = H5VL_file_close(file, vol_plugin, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to close file")
 
 done:
@@ -1570,7 +1570,7 @@ done:
  */
 void *
 H5VLgroup_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                 hid_t gcpl_id, hid_t gapl_id, hid_t req)
+                 hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     void *ret_value = NULL; /* Return value */
 
@@ -1579,7 +1579,7 @@ H5VLgroup_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, co
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
     if(NULL == (ret_value = H5VL_group_create(obj, loc_params, vol_plugin, name, 
-                                              gcpl_id, gapl_id, req)))
+                                              gcpl_id, gapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create group")
 
 done:
@@ -1603,7 +1603,7 @@ done:
  */
 void *
 H5VLgroup_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                hid_t gapl_id, hid_t req)
+                hid_t gapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     void *ret_value; /* Return value */
 
@@ -1612,7 +1612,7 @@ H5VLgroup_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, cons
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
     if(NULL == (ret_value = H5VL_group_open(obj, loc_params, vol_plugin, name, 
-                                              gapl_id, req)))
+                                              gapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to open group")
 
 done:
@@ -1635,7 +1635,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLgroup_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t req, va_list arguments)
+H5VLgroup_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1650,7 +1650,7 @@ H5VLgroup_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t re
             {
                 hid_t *new_gcpl_id = va_arg (arguments, hid_t *);
 
-                if((ret_value = H5VL_group_get(obj, vol_plugin, get_type, req, new_gcpl_id)) < 0)
+                if((ret_value = H5VL_group_get(obj, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, new_gcpl_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get group information")
                 break;
             }
@@ -1660,7 +1660,7 @@ H5VLgroup_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t re
                 H5VL_loc_params_t loc_params = va_arg (arguments, H5VL_loc_params_t);
                 H5G_info_t  *grp_info = va_arg (arguments, H5G_info_t *);
 
-                if((ret_value = H5VL_group_get(obj, vol_plugin, get_type, req, loc_params, grp_info)) < 0)
+                if((ret_value = H5VL_group_get(obj, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, loc_params, grp_info)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get group information")
                 break;
             }
@@ -1688,15 +1688,15 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLgroup_close(void *grp, H5VL_t *vol_plugin, hid_t req)
+H5VLgroup_close(void *grp, H5VL_t *vol_plugin, hid_t dxpl_id, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if(NULL == grp || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_group_close(grp, vol_plugin, req)) < 0)
+    if((ret_value = H5VL_group_close(grp, vol_plugin, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to close group")
 
 done:
@@ -1718,7 +1718,7 @@ done:
  */
 herr_t
 H5VLlink_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, 
-                 H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t req)
+                 H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     herr_t               ret_value = SUCCEED;  /* Return value */
 
@@ -1726,7 +1726,7 @@ H5VLlink_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_
 
     if(NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_link_create(create_type, obj, loc_params, vol_plugin, lcpl_id, lapl_id, req)) < 0)
+    if((ret_value = H5VL_link_create(create_type, obj, loc_params, vol_plugin, lcpl_id, lapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -1748,7 +1748,7 @@ done:
  */
 H5_DLL herr_t H5VLlink_move(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj, 
                              H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin, 
-                             hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t req)
+                             hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     herr_t               ret_value = SUCCEED;  /* Return value */
 
@@ -1757,7 +1757,7 @@ H5_DLL herr_t H5VLlink_move(void *src_obj, H5VL_loc_params_t loc_params1, void *
     if(NULL == src_obj || NULL == dst_obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
     if((ret_value = H5VL_link_move(src_obj, loc_params1, dst_obj, loc_params2, vol_plugin, 
-                                   copy_flag, lcpl_id, lapl_id, req)) < 0)
+                                   copy_flag, lcpl_id, lapl_id, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to move object")
 
 done:
@@ -1780,7 +1780,7 @@ done:
  */
 herr_t H5VLlink_iterate(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
                          hbool_t recursive, H5_index_t idx_type, H5_iter_order_t order, hsize_t *idx, 
-                         H5L_iterate_t op, void *op_data, hid_t req)
+                         H5L_iterate_t op, void *op_data, hid_t dxpl_id, void UNUSED **req)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1789,7 +1789,7 @@ herr_t H5VLlink_iterate(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plu
     if(NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
     if((ret_value = H5VL_link_iterate(obj, loc_params, vol_plugin, recursive, idx_type, order, idx,
-                                      op, op_data, req)) < 0)
+                                      op, op_data, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Link iteration failed")
 
 done:
@@ -1813,7 +1813,7 @@ done:
  */
 herr_t
 H5VLlink_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_get_t get_type, 
-              hid_t req, va_list arguments)
+              hid_t dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1828,7 +1828,7 @@ H5VLlink_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_l
             {
                 htri_t     *ret    = va_arg (arguments, htri_t *);
 
-                if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, get_type, req, ret)) < 0)
+                if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get link information")
                 break;
             }
@@ -1837,7 +1837,7 @@ H5VLlink_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_l
             {
                 H5L_info_t *linfo  = va_arg (arguments, H5L_info_t *);
 
-                if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, get_type, req, linfo)) < 0)
+                if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, linfo)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get link information")
                 break;
             }
@@ -1848,7 +1848,7 @@ H5VLlink_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_l
                 size_t      size   = va_arg (arguments, size_t);
                 ssize_t    *ret    = va_arg (arguments, ssize_t *);
 
-                if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, get_type, req, 
+                if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, 
                                               name, size, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get link information")
                 break;
@@ -1859,7 +1859,7 @@ H5VLlink_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_l
                 void       *buf    = va_arg (arguments, void *);
                 size_t     size    = va_arg (arguments, size_t);
 
-                if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, get_type, req, buf, size)) < 0)
+                if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, buf, size)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to get link information")
                 break;
             }
@@ -1884,7 +1884,7 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-H5_DLL herr_t H5VLlink_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t req)
+H5_DLL herr_t H5VLlink_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t dxpl_id, void UNUSED **req)
 {
     herr_t             ret_value = SUCCEED;    /* Return value */
 
@@ -1892,7 +1892,7 @@ H5_DLL herr_t H5VLlink_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *v
 
     if(NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_link_remove(obj, loc_params, vol_plugin, req)) < 0)
+    if((ret_value = H5VL_link_remove(obj, loc_params, vol_plugin, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to remove link")
 
 done:
@@ -1916,7 +1916,7 @@ done:
  */
 void *
 H5VLobject_open(void *obj, H5VL_loc_params_t params, H5VL_t *vol_plugin, H5I_type_t *opened_type,
-                hid_t req)
+                hid_t dxpl_id, void UNUSED **req)
 {
     void *ret_value;              /* Return value */
 
@@ -1924,7 +1924,7 @@ H5VLobject_open(void *obj, H5VL_loc_params_t params, H5VL_t *vol_plugin, H5I_typ
 
     if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_object_open(obj, params, vol_plugin, opened_type, req)))
+    if(NULL == (ret_value = H5VL_object_open(obj, params, vol_plugin, opened_type, dxpl_id, H5_EVENT_QUEUE_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create group")
 
 done:
@@ -1948,9 +1948,9 @@ done:
 herr_t 
 H5VLobject_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugin1, const char *src_name, 
                 void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin2, const char *dst_name, 
-                hid_t ocpypl_id, hid_t lcpl_id, hid_t req)
+                hid_t ocpypl_id, hid_t lcpl_id, hid_t dxpl_id, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
@@ -1959,7 +1959,7 @@ H5VLobject_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugin
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
     if((ret_value = H5VL_object_copy(src_obj, loc_params1, vol_plugin1, src_name, 
                                      dst_obj, loc_params2, vol_plugin2, dst_name,
-                                     ocpypl_id, lcpl_id, req)) < 0)
+                                     ocpypl_id, lcpl_id, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to move object")
 
 done:
@@ -1981,7 +1981,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t H5VLobject_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5_index_t idx_type,
-                         H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t req)
+                         H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t dxpl_id, void UNUSED **req)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1990,7 +1990,7 @@ herr_t H5VLobject_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plu
     if(NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
     if((ret_value = H5VL_object_visit(obj, loc_params, vol_plugin, idx_type, order, 
-                                      op, op_data, req)) < 0)
+                                      op, op_data, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Object Visit Failed")
 
 done:
@@ -2014,7 +2014,7 @@ done:
  */
 herr_t
 H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, 
-               hid_t req, va_list arguments)
+               hid_t dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -2029,7 +2029,7 @@ H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL
             {
                 htri_t	  *ret      = va_arg (arguments, htri_t *);
 
-                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, req, ret)) < 0)
+                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Object Visit Failed")
                 break;
             }
@@ -2038,7 +2038,7 @@ H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL
             {
                 H5O_info_t  *obj_info = va_arg (arguments, H5O_info_t *);
 
-                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, req, obj_info)) < 0)
+                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL, obj_info)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Object Visit Failed")
                 break;
             }
@@ -2049,7 +2049,7 @@ H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL
                 size_t   bufsize  =  va_arg (arguments, size_t);
                 ssize_t  *ret     =  va_arg (arguments, ssize_t *);
 
-                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, req,
+                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL,
                                                 comment, bufsize, ret)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Object Visit Failed")
                 break;
@@ -2061,7 +2061,7 @@ H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL
                 H5R_type_t  ref_type =  va_arg (arguments, H5R_type_t);
                 void        *ref     =  va_arg (arguments, void *);
 
-                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, req,
+                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL,
                                                 ret, ref_type, ref)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Object Visit Failed")
                 break;
@@ -2073,7 +2073,7 @@ H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL
                 H5R_type_t  ref_type   =  va_arg (arguments, H5R_type_t);
                 void        *ref       =  va_arg (arguments, void *);
 
-                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, req,
+                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL,
                                                 obj_type, ref_type, ref)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Object Visit Failed")
                 break;
@@ -2087,7 +2087,7 @@ H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL
                 H5R_type_t  ref_type   = va_arg (arguments, H5R_type_t);
                 void        *ref       = va_arg (arguments, void *);
 
-                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, req,
+                if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, get_type, dxpl_id, H5_EVENT_QUEUE_NULL,
                                                 ret, name, size, ref_type, ref)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Object Visit Failed")
                 break;
@@ -2116,7 +2116,7 @@ done:
  */
 herr_t
 H5VLobject_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t misc_type, 
-                hid_t req, va_list arguments)
+                hid_t dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -2132,7 +2132,7 @@ H5VLobject_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5V
                 const char    *old_name  = va_arg (arguments, const char *);
                 const char    *new_name  = va_arg (arguments, const char *);
 
-                if((ret_value = H5VL_object_misc(obj, loc_params, vol_plugin, misc_type, req,
+                if((ret_value = H5VL_object_misc(obj, loc_params, vol_plugin, misc_type, dxpl_id, H5_EVENT_QUEUE_NULL,
                                                  old_name, new_name)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Object Visit Failed")
                 break;
@@ -2142,7 +2142,7 @@ H5VLobject_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5V
             {
                 int update_ref  = va_arg (arguments, int);
 
-                if((ret_value = H5VL_object_misc(obj, loc_params, vol_plugin, misc_type, req, update_ref)) < 0)
+                if((ret_value = H5VL_object_misc(obj, loc_params, vol_plugin, misc_type, dxpl_id, H5_EVENT_QUEUE_NULL, update_ref)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Object Visit Failed")
                 break;
             }
@@ -2151,7 +2151,7 @@ H5VLobject_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5V
             {
                 const char    *comment  = va_arg (arguments, char *);
 
-                if((ret_value = H5VL_object_misc(obj, loc_params, vol_plugin, misc_type, req, comment)) < 0)
+                if((ret_value = H5VL_object_misc(obj, loc_params, vol_plugin, misc_type, dxpl_id, H5_EVENT_QUEUE_NULL, comment)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Object Visit Failed")
                 break;
             }
@@ -2162,7 +2162,7 @@ H5VLobject_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5V
                 H5R_type_t  ref_type  = va_arg (arguments, H5R_type_t);
                 hid_t       space_id  = va_arg (arguments, hid_t);
 
-                if((ret_value = H5VL_object_misc(obj, loc_params, vol_plugin, misc_type, req,
+                if((ret_value = H5VL_object_misc(obj, loc_params, vol_plugin, misc_type, dxpl_id, H5_EVENT_QUEUE_NULL,
                                                  ref, name, ref_type, space_id)) < 0)
                     HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "Object Visit Failed")
                 break;
@@ -2191,17 +2191,107 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLobject_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t req)
+H5VLobject_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t dxpl_id, void UNUSED **req)
 {
-    herr_t              ret_value = SUCCEED;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
     if(NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_object_close(obj, loc_params, vol_plugin, req)) < 0)
+    if((ret_value = H5VL_object_close(obj, loc_params, vol_plugin, dxpl_id, H5_EVENT_QUEUE_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to close object")
 
 done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5VLobject_close() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5VLrequest_cancel
+ *
+ * Purpose:	Cancels a request through the VOL
+ *
+ * Return:	Success:	Non Negative
+ *		Failure:	Negative
+ *
+ * Programmer:	Mohamad Chaarawi
+ *              March, 2013
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VLrequest_cancel(void **req, H5VL_t *vol_plugin, H5_status_t *status)
+{
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_API(FAIL)
+
+    if(NULL == vol_plugin || NULL == vol_plugin->cls)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid request/VOL class pointer")
+    if((ret_value = H5VL_request_cancel(req, vol_plugin, status)) < 0)
+	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to cancel request")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5VLrequest_cancel() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5VLrequest_test
+ *
+ * Purpose:	Tests a request through the VOL
+ *
+ * Return:	Success:	Non Negative
+ *		Failure:	Negative
+ *
+ * Programmer:	Mohamad Chaarawi
+ *              March, 2013
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VLrequest_test(void **req, H5VL_t *vol_plugin, H5_status_t *status)
+{
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_API(FAIL)
+
+    if(NULL == vol_plugin || NULL == vol_plugin->cls)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid request/VOL class pointer")
+    if((ret_value = H5VL_request_test(req, vol_plugin, status)) < 0)
+	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to test request")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5VLrequest_test() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5VLrequest_wait
+ *
+ * Purpose:	Waits on a request through the VOL
+ *
+ * Return:	Success:	Non Negative
+ *		Failure:	Negative
+ *
+ * Programmer:	Mohamad Chaarawi
+ *              March, 2013
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VLrequest_wait(void **req, H5VL_t *vol_plugin, H5_status_t *status)
+{
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_API(FAIL)
+
+    if(NULL == vol_plugin || NULL == vol_plugin->cls)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid request/VOL class pointer")
+    if((ret_value = H5VL_request_wait(req, vol_plugin, status)) < 0)
+	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to wait on request")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5VLrequest_wait() */
diff --git a/src/H5VLint.c b/src/H5VLint.c
index 25b6fd2..90ed9d6 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -387,7 +387,7 @@ H5VL_object_register(void *obj, H5I_type_t obj_type, H5VL_t *vol_plugin, hbool_t
             break;
 
         case H5I_DATATYPE:
-            if ((ret_value = H5VL_create_datatype(obj, vol_plugin, app_ref, H5_REQUEST_NULL)) < 0)
+            if ((ret_value = H5VL_create_datatype(obj, vol_plugin, app_ref)) < 0)
                 HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize datatype handle")
             break;
 
@@ -467,7 +467,7 @@ done:
  */
 void *
 H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                 hid_t acpl_id, hid_t aapl_id, hid_t req)
+                 hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value;  /* Return value */
 
@@ -476,8 +476,10 @@ H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, co
     /* check if the corresponding VOL create callback exists */
     if(NULL == vol_plugin->cls->attr_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `attr create' method")
+
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_plugin->cls->attr_cls.create) (obj, loc_params, name, acpl_id, aapl_id, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->attr_cls.create) (obj, loc_params, name, acpl_id, 
+                                                                aapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
 
     vol_plugin->nrefs ++;
@@ -501,7 +503,8 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t aapl_id, hid_t req)
+H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+               hid_t aapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value;  /* Return value */
 
@@ -511,7 +514,7 @@ H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, cons
     if(NULL == vol_plugin->cls->attr_cls.open)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `attr open' method")
     /* call the corresponding VOL open callback */
-    if(NULL == (ret_value = (vol_plugin->cls->attr_cls.open) (obj, loc_params, name, aapl_id, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->attr_cls.open) (obj, loc_params, name, aapl_id, dxpl_id, H5_REQUEST_NULL)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "attribute open failed")
 
     vol_plugin->nrefs ++;
@@ -534,7 +537,8 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VL_attr_read(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, void *buf, hid_t req)
+herr_t H5VL_attr_read(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, void *buf, 
+                      hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -542,7 +546,7 @@ herr_t H5VL_attr_read(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, void *b
 
     if(NULL == vol_plugin->cls->attr_cls.read)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr read' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.read)(attr, mem_type_id, buf, req)) < 0)
+    if((ret_value = (vol_plugin->cls->attr_cls.read)(attr, mem_type_id, buf, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "read failed")
 
 done:
@@ -564,7 +568,8 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VL_attr_write(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, const void *buf, hid_t req)
+herr_t H5VL_attr_write(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, const void *buf, 
+                       hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -572,7 +577,7 @@ herr_t H5VL_attr_write(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, const
 
     if(NULL == vol_plugin->cls->attr_cls.write)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr write' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.write)(attr, mem_type_id, buf, req)) < 0)
+    if((ret_value = (vol_plugin->cls->attr_cls.write)(attr, mem_type_id, buf, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "write failed")
 
 done:
@@ -595,7 +600,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_attr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req, ...)
+H5VL_attr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, 
+              hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -604,8 +610,8 @@ H5VL_attr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req
 
     if(NULL == vol_plugin->cls->attr_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr get' method")
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->attr_cls.get)(obj, get_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->attr_cls.get)(obj, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
 #if 0
@@ -613,7 +619,7 @@ H5VL_attr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req
     if(H5VL_ATTR_GET_TYPE == get_type) {
         hid_t           *ret_id;
 
-        va_start (arguments, req);
+        va_start (arguments, event_q);
         ret_id = va_arg (arguments, hid_t *);
 
         if(H5Tcommitted(*ret_id)) {
@@ -645,7 +651,7 @@ done:
  */
 herr_t 
 H5VL_attr_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
-                 const char *attr_name, hid_t req)
+                 const char *attr_name, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -653,7 +659,7 @@ H5VL_attr_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
 
     if(NULL == vol_plugin->cls->attr_cls.remove)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr remove' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.remove)(obj, loc_params, attr_name, req)) < 0)
+    if((ret_value = (vol_plugin->cls->attr_cls.remove)(obj, loc_params, attr_name, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTDELETE, FAIL, "remove failed")
 
 done:
@@ -676,7 +682,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_attr_close(void *attr, H5VL_t *vol_plugin, hid_t req)
+H5VL_attr_close(void *attr, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -687,19 +693,18 @@ H5VL_attr_close(void *attr, H5VL_t *vol_plugin, hid_t req)
     if(NULL == vol_plugin->cls->attr_cls.close){
         HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr close' method")
         /*
-        if(H5VL_object_close(id, req) < 0)
+        if(H5VL_object_close(id, dxpl_id, event_q) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTRELEASE, FAIL, "unable to close object")
         */
     }
-    else if((ret_value = (vol_plugin->cls->attr_cls.close)(attr, req)) < 0)
+    else if((ret_value = (vol_plugin->cls->attr_cls.close)(attr, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
 
     vol_plugin->nrefs --;
+
     if (0 == vol_plugin->nrefs) {
-        if (NULL != vol_plugin->container_name)
-            H5MM_xfree(vol_plugin->container_name);
-        if (NULL != vol_plugin)
-            H5MM_free(vol_plugin);
+        vol_plugin->container_name = (const char *)H5MM_xfree(vol_plugin->container_name);
+        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
     }
 
 done:
@@ -723,7 +728,8 @@ done:
  */
 void *
 H5VL_datatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                     hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t req)
+                     hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, 
+                     hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value = NULL;              /* Return value */
 
@@ -735,7 +741,7 @@ H5VL_datatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin
 
     /* call the corresponding VOL commit callback */
     if(NULL == (ret_value = (vol_plugin->cls->datatype_cls.commit) 
-        (obj, loc_params, name, type_id, lcpl_id, tcpl_id, tapl_id, req)))
+        (obj, loc_params, name, type_id, lcpl_id, tcpl_id, tapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "commit failed")
     vol_plugin->nrefs ++;
 
@@ -760,7 +766,7 @@ done:
  */
 void *
 H5VL_datatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                   hid_t tapl_id, hid_t req)
+                   hid_t tapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value = NULL;              /* Return value */
 
@@ -777,11 +783,11 @@ H5VL_datatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
         loc_params.loc_data.loc_by_name.plist_id = tapl_id;
 
         /* Open the object class */
-        if((ret_value = H5VL_object_open(id, loc_params, H5_REQUEST_NULL)) < 0)
+        if((ret_value = H5VL_object_open(id, loc_params, dxpl_id, event_q)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, NULL, "unable to open object")
 #endif
     /* call the corresponding VOL open callback */
-    if(NULL == (ret_value = (vol_plugin->cls->datatype_cls.open)(obj, loc_params, name, tapl_id, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->datatype_cls.open)(obj, loc_params, name, tapl_id, dxpl_id, H5_REQUEST_NULL)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "open failed")
     vol_plugin->nrefs ++;
 
@@ -805,7 +811,8 @@ done:
  *-------------------------------------------------------------------------
  */
 ssize_t 
-H5VL_datatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size_t size, hid_t req)
+H5VL_datatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size_t size, 
+                         hid_t dxpl_id, hid_t UNUSED event_q)
 {
     ssize_t ret_value = FAIL;
 
@@ -815,7 +822,7 @@ H5VL_datatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size
     if(NULL == vol_plugin->cls->datatype_cls.get_binary)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "no datatype get_binary callback");
     /* call the corresponding VOL open callback */
-    if((ret_value = (vol_plugin->cls->datatype_cls.get_binary)(obj, buf, size, req)) < 0)
+    if((ret_value = (vol_plugin->cls->datatype_cls.get_binary)(obj, buf, size, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "get binary failed")
 
 done:
@@ -837,7 +844,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_datatype_close(void *dt, H5VL_t *vol_plugin, hid_t req)
+H5VL_datatype_close(void *dt, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t		ret_value = SUCCEED;    /* Return value */
 
@@ -848,15 +855,13 @@ H5VL_datatype_close(void *dt, H5VL_t *vol_plugin, hid_t req)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `datatype close' method")
 
     /* call the corresponding VOL close callback */
-    if((ret_value = (vol_plugin->cls->datatype_cls.close)(dt, req)) < 0)
+    if((ret_value = (vol_plugin->cls->datatype_cls.close)(dt, dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
 
     vol_plugin->nrefs --;
     if (0 == vol_plugin->nrefs) {
-        if (NULL != vol_plugin->container_name)
-            H5MM_xfree(vol_plugin->container_name);
-        if (NULL != vol_plugin)
-            H5MM_free(vol_plugin);
+        vol_plugin->container_name = (const char *)H5MM_xfree(vol_plugin->container_name);
+        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
     }
 
 done:
@@ -880,7 +885,7 @@ done:
  */
 void *
 H5VL_dataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                    hid_t dcpl_id, hid_t dapl_id, hid_t req)
+                    hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value; /* Return value */
 
@@ -890,7 +895,7 @@ H5VL_dataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
     if(NULL == vol_plugin->cls->dataset_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `dataset create' method")
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_plugin->cls->dataset_cls.create)(obj, loc_params, name, dcpl_id, dapl_id, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->dataset_cls.create)(obj, loc_params, name, dcpl_id, dapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
     vol_plugin->nrefs ++;
 
@@ -915,7 +920,7 @@ done:
  */
 void *
 H5VL_dataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                  hid_t dapl_id, hid_t req)
+                  hid_t dapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value; /* Return value */
 
@@ -926,13 +931,13 @@ H5VL_dataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, c
         ;
 #if 0
         /* Open the object class */
-        if((ret_value = H5VL_object_open(id, loc_params, H5_REQUEST_NULL)) < 0)
+        if((ret_value = H5VL_object_open(id, loc_params, dxpl_id, event_q)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, NULL, "unable to open object")
 #endif
     }
     else {
         /* call the corresponding VOL open callback */
-        if(NULL == (ret_value = (vol_plugin->cls->dataset_cls.open)(obj, loc_params, name, dapl_id, req)))
+        if(NULL == (ret_value = (vol_plugin->cls->dataset_cls.open)(obj, loc_params, name, dapl_id, dxpl_id, H5_REQUEST_NULL)))
             HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "open failed")
         vol_plugin->nrefs ++;
 
@@ -958,7 +963,7 @@ done:
  */
 herr_t 
 H5VL_dataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, 
-                  hid_t file_space_id, hid_t plist_id, void *buf, hid_t req)
+                  hid_t file_space_id, hid_t plist_id, void *buf, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -967,7 +972,7 @@ H5VL_dataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_s
     if(NULL == vol_plugin->cls->dataset_cls.read)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset read' method")
     if((ret_value = (vol_plugin->cls->dataset_cls.read)
-        (dset, mem_type_id, mem_space_id, file_space_id, plist_id, buf, req)) < 0)
+        (dset, mem_type_id, mem_space_id, file_space_id, plist_id, buf, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_READERROR, FAIL, "read failed")
 
 done:
@@ -991,7 +996,7 @@ done:
  */
 herr_t 
 H5VL_dataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, 
-                   hid_t file_space_id, hid_t plist_id, const void *buf, hid_t req)
+                   hid_t file_space_id, hid_t plist_id, const void *buf, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1000,7 +1005,7 @@ H5VL_dataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_
     if(NULL == vol_plugin->cls->dataset_cls.write)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset write' method")
     if((ret_value = (vol_plugin->cls->dataset_cls.write)
-        (dset, mem_type_id, mem_space_id, file_space_id, plist_id, buf, req)) < 0)
+        (dset, mem_type_id, mem_space_id, file_space_id, plist_id, buf, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_WRITEERROR, FAIL, "write failed")
 
 done:
@@ -1023,7 +1028,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t 
-H5VL_dataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], hid_t req)
+H5VL_dataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], 
+                        hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1031,7 +1037,7 @@ H5VL_dataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], hi
 
     if(NULL == vol_plugin->cls->dataset_cls.set_extent)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset set_extent' method")
-    if((ret_value = (vol_plugin->cls->dataset_cls.set_extent)(dset, size, req)) < 0)
+    if((ret_value = (vol_plugin->cls->dataset_cls.set_extent)(dset, size, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "set_extent failed")
 
 done:
@@ -1054,7 +1060,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid_t req, ...)
+H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, 
+                 hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1064,8 +1071,8 @@ H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hi
     if(NULL == vol_plugin->cls->dataset_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset get' method")
 
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->dataset_cls.get)(dset, get_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->dataset_cls.get)(dset, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
 
@@ -1074,7 +1081,7 @@ H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hi
     if(H5VL_DATASET_GET_TYPE == get_type) {
         hid_t           *ret_id;
 
-        va_start (arguments, req);
+        va_start (arguments, event_q);
         ret_id = va_arg (arguments, hid_t *);
 
         if(H5Tcommitted(*ret_id)) {
@@ -1106,7 +1113,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_dataset_close(void *dset, H5VL_t *vol_plugin, hid_t req)
+H5VL_dataset_close(void *dset, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1117,22 +1124,21 @@ H5VL_dataset_close(void *dset, H5VL_t *vol_plugin, hid_t req)
     if(NULL == vol_plugin->cls->dataset_cls.close){
         ;
 #if 0
-        if(H5VL_object_close(id, req) < 0)
+        if(H5VL_object_close(id, dxpl_id, dxpl_id, event_q) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTRELEASE, FAIL, "unable to close object")
 #endif
     }
     else {
-        if((ret_value = (vol_plugin->cls->dataset_cls.close)(dset, req)) < 0)
+        if((ret_value = (vol_plugin->cls->dataset_cls.close)(dset, dxpl_id, H5_REQUEST_NULL)) < 0)
             HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
     }
 
     vol_plugin->nrefs --;
     if (0 == vol_plugin->nrefs) {
-        if (NULL != vol_plugin->container_name)
-            H5MM_xfree(vol_plugin->container_name);
-        if (NULL != vol_plugin)
-            H5MM_free(vol_plugin);
+        vol_plugin->container_name = (const char *)H5MM_xfree(vol_plugin->container_name);
+        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
     }
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_dataset_close() */
@@ -1154,7 +1160,7 @@ done:
  */
 void *
 H5VL_file_create(H5VL_t **plugin, const char *name, unsigned flags, hid_t fcpl_id, 
-                 hid_t fapl_id, hid_t req)
+                 hid_t fapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     H5P_genplist_t     *plist;                 /* Property list pointer */
     H5VL_class_t       *vol_cls;               /* VOL class attached to fapl_id */
@@ -1173,7 +1179,7 @@ H5VL_file_create(H5VL_t **plugin, const char *name, unsigned flags, hid_t fcpl_i
     if(NULL == vol_cls->file_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `file create' method")
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_cls->file_cls.create)(name, flags, fcpl_id, fapl_id, req)))
+    if(NULL == (ret_value = (vol_cls->file_cls.create)(name, flags, fcpl_id, fapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
 
     /* Build the vol plugin struct */
@@ -1206,7 +1212,8 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_file_open(H5VL_t **plugin, const char *name, unsigned flags, hid_t fapl_id, hid_t req)
+H5VL_file_open(H5VL_t **plugin, const char *name, unsigned flags, hid_t fapl_id, 
+               hid_t dxpl_id, hid_t UNUSED event_q)
 {
     H5P_genplist_t     *plist;                 /* Property list pointer */
     H5VL_class_t       *vol_cls;               /* VOL class attached to fapl_id */
@@ -1225,7 +1232,7 @@ H5VL_file_open(H5VL_t **plugin, const char *name, unsigned flags, hid_t fapl_id,
     if(NULL == vol_cls->file_cls.open)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `file open' method")
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_cls->file_cls.open)(name, flags, fapl_id, req)))
+    if(NULL == (ret_value = (vol_cls->file_cls.open)(name, flags, fapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "open failed")
 
     /* Build the vol plugin struct */
@@ -1258,7 +1265,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_flush(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5F_scope_t scope, hid_t req)
+H5VL_file_flush(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5F_scope_t scope, 
+                hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1266,7 +1274,7 @@ H5VL_file_flush(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5F
 
     if(NULL == vol_plugin->cls->file_cls.flush)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file flush' method")
-    if((ret_value = (vol_plugin->cls->file_cls.flush)(obj, loc_params, scope, req)) < 0)
+    if((ret_value = (vol_plugin->cls->file_cls.flush)(obj, loc_params, scope, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTFLUSH, FAIL, "flush failed")
 
 done:
@@ -1289,7 +1297,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req, ...)
+H5VL_file_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, 
+              hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1299,8 +1308,8 @@ H5VL_file_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t re
     if(NULL == vol_plugin->cls->file_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file get' method")
 
-    va_start(arguments, req);
-    if((ret_value = (vol_plugin->cls->file_cls.get)(file, get_type, req, arguments)) < 0)
+    va_start(arguments, event_q);
+    if((ret_value = (vol_plugin->cls->file_cls.get)(file, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end(arguments);
 
@@ -1323,7 +1332,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t req, ...)
+H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, 
+               hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1336,7 +1346,7 @@ H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t
         va_list             tmp_args;       /* argument list passed from the API call */
         hid_t               fapl_id;
 
-        va_start (tmp_args, req);
+        va_start (tmp_args, event_q);
         fapl_id = va_arg (tmp_args, hid_t);
         va_end (tmp_args);
 
@@ -1346,8 +1356,8 @@ H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t
         if(H5P_get(plist, H5F_ACS_VOL_NAME, &vol_cls) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get vol plugin")
 
-        va_start (arguments, req);
-        if((ret_value = (vol_cls->file_cls.misc)(file, misc_type, req, arguments)) < 0)
+        va_start (arguments, event_q);
+        if((ret_value = (vol_cls->file_cls.misc)(file, misc_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
             HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "misc failed")
         va_end (arguments);
     }
@@ -1355,8 +1365,8 @@ H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t
         if(NULL == vol_plugin->cls->file_cls.misc)
             HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file misc' method")
 
-        va_start (arguments, req);
-        if((ret_value = (vol_plugin->cls->file_cls.misc)(file, misc_type, req, arguments)) < 0)
+        va_start (arguments, event_q);
+        if((ret_value = (vol_plugin->cls->file_cls.misc)(file, misc_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
             HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "misc failed")
         va_end (arguments);
     }
@@ -1380,7 +1390,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_type, hid_t req, ...)
+H5VL_file_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_type, 
+                   hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1390,8 +1401,8 @@ H5VL_file_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional
     if(NULL == vol_plugin->cls->file_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file optional' method")
 
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->file_cls.optional)(file, optional_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->file_cls.optional)(file, optional_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "optional failed")
     va_end (arguments);
 
@@ -1420,7 +1431,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_close(void *file, H5VL_t *vol_plugin, hid_t req)
+H5VL_file_close(void *file, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1428,16 +1439,15 @@ H5VL_file_close(void *file, H5VL_t *vol_plugin, hid_t req)
 
     if(NULL == vol_plugin->cls->file_cls.close)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file close' method")
-    if((ret_value = (vol_plugin->cls->file_cls.close)(file, req)) < 0)
+    if((ret_value = (vol_plugin->cls->file_cls.close)(file, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTCLOSEFILE, FAIL, "close failed")
 
     vol_plugin->nrefs --;
     if (0 == vol_plugin->nrefs) {
-        if (NULL != vol_plugin->container_name)
-            H5MM_xfree(vol_plugin->container_name);
-        if (NULL != vol_plugin)
-            H5MM_free(vol_plugin);
+        vol_plugin->container_name = (const char *)H5MM_xfree(vol_plugin->container_name);
+        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
     }
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_file_close() */
@@ -1459,7 +1469,7 @@ done:
  */
 void *
 H5VL_group_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                  hid_t gcpl_id, hid_t gapl_id, hid_t req)
+                  hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value = NULL; /* Return value */
 
@@ -1469,7 +1479,7 @@ H5VL_group_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, c
     if(NULL == vol_plugin->cls->group_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `group create' method")
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_plugin->cls->group_cls.create)(obj, loc_params, name, gcpl_id, gapl_id, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->group_cls.create)(obj, loc_params, name, gcpl_id, gapl_id, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
     vol_plugin->nrefs ++;
 
@@ -1494,7 +1504,7 @@ done:
  */
 void *
 H5VL_group_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
-                hid_t gapl_id, hid_t req)
+                hid_t gapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value; /* Return value */
 
@@ -1505,13 +1515,13 @@ H5VL_group_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, con
         ;
 #if 0
         /* Open the object class */
-        if((ret_value = H5VL_object_open(id, loc_params, H5_REQUEST_NULL)) < 0)
+        if((ret_value = H5VL_object_open(id, loc_params, dxpl_id, event_q)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, NULL, "unable to open object")
 #endif
     }
     else {
         /* call the corresponding VOL open callback */
-        if(NULL == (ret_value = (vol_plugin->cls->group_cls.open)(obj, loc_params, name, gapl_id, req)))
+        if(NULL == (ret_value = (vol_plugin->cls->group_cls.open)(obj, loc_params, name, gapl_id, dxpl_id, H5_REQUEST_NULL)))
             HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "open failed")
         vol_plugin->nrefs ++;
     }
@@ -1535,7 +1545,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_group_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t req, ...)
+H5VL_group_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, 
+               hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1544,8 +1555,8 @@ H5VL_group_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t r
 
     if(NULL == vol_plugin->cls->group_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `group get' method")
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->group_cls.get)(obj, get_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->group_cls.get)(obj, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
 
@@ -1569,7 +1580,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_group_close(void *grp, H5VL_t *vol_plugin, hid_t req)
+H5VL_group_close(void *grp, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1580,21 +1591,19 @@ H5VL_group_close(void *grp, H5VL_t *vol_plugin, hid_t req)
     if(NULL == vol_plugin->cls->group_cls.close) {
         ;
 #if 0
-        if(H5VL_object_close(id, req) < 0)
+        if(H5VL_object_close(id, dxpl_id, event_q) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTRELEASE, FAIL, "unable to close object")
 #endif
     }
     else {
-        if((ret_value = (vol_plugin->cls->group_cls.close)(grp, req)) < 0)
+        if((ret_value = (vol_plugin->cls->group_cls.close)(grp, dxpl_id, H5_REQUEST_NULL)) < 0)
             HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
    }
 
     vol_plugin->nrefs --;
     if (0 == vol_plugin->nrefs) {
-        if (NULL != vol_plugin->container_name)
-            H5MM_xfree(vol_plugin->container_name);
-        if (NULL != vol_plugin)
-            H5MM_free(vol_plugin);
+        vol_plugin->container_name = (const char *)H5MM_xfree(vol_plugin->container_name);
+        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
     }
 
 done:
@@ -1616,7 +1625,7 @@ done:
  */
 herr_t
 H5VL_link_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, 
-                 H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t req)
+                 H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t               ret_value = SUCCEED;  /* Return value */
 
@@ -1627,7 +1636,7 @@ H5VL_link_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link create' method")
     /* call the corresponding VOL create callback */
     if((ret_value = (vol_plugin->cls->link_cls.create)
-        (create_type, obj, loc_params, lcpl_id, lapl_id, req)) < 0)
+        (create_type, obj, loc_params, lcpl_id, lapl_id, dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "link create failed")
 
 done:
@@ -1647,9 +1656,10 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-H5_DLL herr_t H5VL_link_move(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj, 
-                             H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin, 
-                             hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t req)
+herr_t 
+H5VL_link_move(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj,
+               H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin, hbool_t copy_flag, 
+               hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t               ret_value = SUCCEED;  /* Return value */
 
@@ -1660,7 +1670,7 @@ H5_DLL herr_t H5VL_link_move(void *src_obj, H5VL_loc_params_t loc_params1, void
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link move' method")
     /* call the corresponding VOL move callback */
     if((ret_value = (vol_plugin->cls->link_cls.move)
-        (src_obj, loc_params1, dst_obj, loc_params2, copy_flag, lcpl_id, lapl_id, req)) < 0)
+        (src_obj, loc_params1, dst_obj, loc_params2, copy_flag, lcpl_id, lapl_id, dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "link move failed")
 
 done:
@@ -1681,9 +1691,10 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VL_link_iterate(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
-                         hbool_t recursive, H5_index_t idx_type, H5_iter_order_t order, hsize_t *idx, 
-                         H5L_iterate_t op, void *op_data, hid_t req)
+herr_t 
+H5VL_link_iterate(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+                  hbool_t recursive, H5_index_t idx_type, H5_iter_order_t order, hsize_t *idx, 
+                  H5L_iterate_t op, void *op_data, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1692,7 +1703,7 @@ herr_t H5VL_link_iterate(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_pl
     if(NULL == vol_plugin->cls->link_cls.iterate)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link iterate' method")
     if((ret_value = (vol_plugin->cls->link_cls.iterate)(obj, loc_params, recursive, idx_type,
-                                                        order, idx, op, op_data, req)) < 0)
+                                                        order, idx, op, op_data, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_BADITER, FAIL, "iteration failed")
 
 done:
@@ -1716,7 +1727,7 @@ done:
  */
 herr_t
 H5VL_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_get_t get_type, 
-              hid_t req, ...)
+              hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1725,8 +1736,8 @@ H5VL_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_
 
     if(NULL == vol_plugin->cls->link_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link get' method")
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->link_cls.get)(obj, loc_params, get_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->link_cls.get)(obj, loc_params, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
 
@@ -1747,7 +1758,9 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-H5_DLL herr_t H5VL_link_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t req)
+herr_t 
+H5VL_link_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+                 hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t             ret_value = SUCCEED;    /* Return value */
 
@@ -1757,7 +1770,7 @@ H5_DLL herr_t H5VL_link_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *
     if(NULL == vol_plugin->cls->link_cls.remove)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link remove' method")
     /* call the corresponding VOL remove callback */
-    if((ret_value = (vol_plugin->cls->link_cls.remove)(obj, loc_params, req)) < 0)
+    if((ret_value = (vol_plugin->cls->link_cls.remove)(obj, loc_params, dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "link remove failed")
 
 done:
@@ -1781,7 +1794,7 @@ done:
  */
 void *
 H5VL_object_open(void *obj, H5VL_loc_params_t params, H5VL_t *vol_plugin, H5I_type_t *opened_type,
-                 hid_t req)
+                 hid_t dxpl_id, hid_t UNUSED event_q)
 {
     void *ret_value;              /* Return value */
 
@@ -1791,7 +1804,7 @@ H5VL_object_open(void *obj, H5VL_loc_params_t params, H5VL_t *vol_plugin, H5I_ty
     if(NULL == vol_plugin->cls->object_cls.open)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `object open' method")
     /* call the corresponding VOL open callback */
-    if(NULL == (ret_value = (vol_plugin->cls->object_cls.open)(obj, params, opened_type, req)))
+    if(NULL == (ret_value = (vol_plugin->cls->object_cls.open)(obj, params, opened_type, dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "open failed")
     vol_plugin->nrefs++;
 
@@ -1816,7 +1829,7 @@ done:
 herr_t 
 H5VL_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugin1, const char *src_name, 
                  void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin2, const char *dst_name, 
-                 hid_t ocpypl_id, hid_t lcpl_id, hid_t req)
+                 hid_t ocpypl_id, hid_t lcpl_id, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -1829,7 +1842,7 @@ H5VL_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugi
     if(NULL == vol_plugin1->cls->object_cls.copy)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object copy' method")
     if((ret_value = (vol_plugin1->cls->object_cls.copy)
-        (src_obj, loc_params1, src_name, dst_obj, loc_params2, dst_name, ocpypl_id, lcpl_id, req)) < 0)
+        (src_obj, loc_params1, src_name, dst_obj, loc_params2, dst_name, ocpypl_id, lcpl_id, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "copy failed")
 
 done:
@@ -1850,8 +1863,9 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VL_object_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5_index_t idx_type,
-                         H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t req)
+herr_t H5VL_object_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+                         H5_index_t idx_type, H5_iter_order_t order, H5O_iterate_t op, 
+                         void *op_data, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t            ret_value = SUCCEED;
 
@@ -1861,7 +1875,7 @@ herr_t H5VL_object_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_pl
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object visit' method")
 
     if((ret_value = (vol_plugin->cls->object_cls.visit)(obj, loc_params, idx_type, order, op, 
-                                                        op_data, req)) < 0)
+                                                        op_data, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_BADITER, FAIL, "object visitation failed")
 
 done:
@@ -1885,7 +1899,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_lookup(hid_t id, H5VL_loc_type_t lookup_type, void **location, hid_t req, ...)
+H5VL_object_lookup(hid_t id, H5VL_loc_type_t lookup_type, void **location, 
+                   hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     H5VL_class_t      *vol_plugin;            /* VOL structure attached to id */
@@ -1899,8 +1914,8 @@ H5VL_object_lookup(hid_t id, H5VL_loc_type_t lookup_type, void **location, hid_t
     if(NULL == vol_plugin->object_cls.lookup)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object lookup' method")
 
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->object_cls.lookup)(id, lookup_type, location, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->object_cls.lookup)(id, lookup_type, location, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "lookup of object location failed")
     va_end (arguments);
 done:
@@ -1922,7 +1937,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_free_loc(hid_t id, void *location, hid_t req)
+H5VL_object_free_loc(hid_t id, void *location, hid_t dxpl_id, hid_t UNUSED event_q)
 {
     H5VL_class_t       *vol_plugin;            /* VOL structure attached to id */
     herr_t            ret_value = SUCCEED;
@@ -1935,7 +1950,7 @@ H5VL_object_free_loc(hid_t id, void *location, hid_t req)
     if(NULL == vol_plugin->object_cls.free_loc)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object free_loc' method")
 
-    if((ret_value = (vol_plugin->object_cls.free_loc)(location, req)) < 0)
+    if((ret_value = (vol_plugin->object_cls.free_loc)(location, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "freeing location token of object location failed")
 
 done:
@@ -1959,7 +1974,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, hid_t req, ...)
+H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, 
+                hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -1969,8 +1985,8 @@ H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5V
     if(NULL == vol_plugin->cls->object_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object get' method")
 
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->object_cls.get)(obj, loc_params, get_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->object_cls.get)(obj, loc_params, get_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
 done:
@@ -1992,7 +2008,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t misc_type, hid_t req, ...)
+H5VL_object_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t misc_type, 
+                 hid_t dxpl_id, hid_t event_q, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
@@ -2002,8 +2019,8 @@ H5VL_object_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5
     if(NULL == vol_plugin->cls->object_cls.misc)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object misc' method")
 
-    va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->object_cls.misc)(obj, loc_params, misc_type, req, arguments)) < 0)
+    va_start (arguments, event_q);
+    if((ret_value = (vol_plugin->cls->object_cls.misc)(obj, loc_params, misc_type, dxpl_id, H5_REQUEST_NULL, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "misc failed")
     va_end (arguments);
 
@@ -2027,7 +2044,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t req)
+H5VL_object_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+                  hid_t dxpl_id, hid_t UNUSED event_q)
 {
     herr_t              ret_value = SUCCEED;
 
@@ -2035,9 +2053,99 @@ H5VL_object_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, h
 
     if(NULL == vol_plugin->cls->object_cls.close)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object close' method")
-    if((ret_value = (vol_plugin->cls->object_cls.close)(obj, loc_params, req)) < 0)
+    if((ret_value = (vol_plugin->cls->object_cls.close)(obj, loc_params, dxpl_id, H5_REQUEST_NULL)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_object_close() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5VL_request_cancel
+ *
+ * Purpose:	Cancels a request through the VOL
+ *
+ * Return:	Success:	Non Negative
+ *		Failure:	Negative
+ *
+ * Programmer:	Mohamad Chaarawi
+ *              March, 2013
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VL_request_cancel(void **req, H5VL_t *vol_plugin, H5_status_t *status)
+{
+    herr_t              ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    if(NULL == vol_plugin->cls->async_cls.cancel)
+	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `async cancel' method");
+    if((ret_value = (vol_plugin->cls->async_cls.cancel)(req, status)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "request cancel failed")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_request_cancel() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5VL_request_test
+ *
+ * Purpose:	Tests a request through the VOL
+ *
+ * Return:	Success:	Non Negative
+ *		Failure:	Negative
+ *
+ * Programmer:	Mohamad Chaarawi
+ *              March, 2013
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VL_request_test(void **req, H5VL_t *vol_plugin, H5_status_t *status)
+{
+    herr_t              ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    if(NULL == vol_plugin->cls->async_cls.test)
+	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `async test' method");
+    if((ret_value = (vol_plugin->cls->async_cls.test)(req, status)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "request test failed")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_request_test() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5VL_request_wait
+ *
+ * Purpose:	Waits a request through the VOL
+ *
+ * Return:	Success:	Non Negative
+ *		Failure:	Negative
+ *
+ * Programmer:	Mohamad Chaarawi
+ *              March, 2013
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VL_request_wait(void **req, H5VL_t *vol_plugin, H5_status_t *status)
+{
+    herr_t              ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    if(NULL == vol_plugin->cls->async_cls.wait)
+	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `async wait' method");
+    if((ret_value = (vol_plugin->cls->async_cls.wait)(req, status)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "request wait failed")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_request_wait() */
diff --git a/src/H5VLnative.c b/src/H5VLnative.c
index 5900068..be62be2 100644
--- a/src/H5VLnative.c
+++ b/src/H5VLnative.c
@@ -62,71 +62,69 @@
 static H5F_t *H5VL_native_get_file(void *obj, H5I_type_t type);
 
 /* Atrribute callbacks */
-static void *H5VL_native_attr_create(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t req);
-static void *H5VL_native_attr_open(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t aapl_id, hid_t req);
-static herr_t H5VL_native_attr_read(void *attr, hid_t dtype_id, void *buf, hid_t req);
-static herr_t H5VL_native_attr_write(void *attr, hid_t dtype_id, const void *buf, hid_t req);
-static herr_t H5VL_native_attr_get(void *obj, H5VL_attr_get_t get_type, hid_t req, va_list arguments);
-static herr_t H5VL_native_attr_remove(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t req);
-static herr_t H5VL_native_attr_close(void *attr, hid_t req);
+static void *H5VL_native_attr_create(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req);
+static void *H5VL_native_attr_open(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t aapl_id, hid_t dxpl_id, void **req);
+static herr_t H5VL_native_attr_read(void *attr, hid_t dtype_id, void *buf, hid_t dxpl_id, void **req);
+static herr_t H5VL_native_attr_write(void *attr, hid_t dtype_id, const void *buf, hid_t dxpl_id, void **req);
+static herr_t H5VL_native_attr_get(void *obj, H5VL_attr_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+static herr_t H5VL_native_attr_remove(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t dxpl_id, void **req);
+static herr_t H5VL_native_attr_close(void *attr, hid_t dxpl_id, void **req);
 
 /* Datatype callbacks */
-static void *H5VL_native_datatype_commit(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t req);
-static void *H5VL_native_datatype_open(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t tapl_id, hid_t req);
-static ssize_t H5VL_native_datatype_get_binary(void *obj, unsigned char *buf, size_t size, hid_t req);
-static herr_t H5VL_native_datatype_close(void *dt, hid_t req);
+static void *H5VL_native_datatype_commit(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t dxpl_id, void **req);
+static void *H5VL_native_datatype_open(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t tapl_id, hid_t dxpl_id, void **req);
+static ssize_t H5VL_native_datatype_get_binary(void *obj, unsigned char *buf, size_t size, hid_t dxpl_id, void **req);
+static herr_t H5VL_native_datatype_close(void *dt, hid_t dxpl_id, void **req);
 
 /* Dataset callbacks */
-static void *H5VL_native_dataset_create(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t req);
-static void *H5VL_native_dataset_open(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t dapl_id, hid_t req);
+static void *H5VL_native_dataset_create(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, void **req);
+static void *H5VL_native_dataset_open(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t dapl_id, hid_t dxpl_id, void **req);
 static herr_t H5VL_native_dataset_read(void *dset, hid_t mem_type_id, hid_t mem_space_id,
-                                       hid_t file_space_id, hid_t plist_id, void *buf, hid_t req);
+                                       hid_t file_space_id, hid_t plist_id, void *buf, void **req);
 static herr_t H5VL_native_dataset_write(void *dset, hid_t mem_type_id, hid_t mem_space_id,
-                                        hid_t file_space_id, hid_t plist_id, const void *buf, hid_t req);
-static herr_t H5VL_native_dataset_set_extent(void *dset, const hsize_t size[], hid_t req);
-static herr_t H5VL_native_dataset_get(void *dset, H5VL_dataset_get_t get_type, hid_t req, va_list arguments);
-static herr_t H5VL_native_dataset_close(void *dset, hid_t req);
+                                        hid_t file_space_id, hid_t plist_id, const void *buf, void **req);
+static herr_t H5VL_native_dataset_set_extent(void *dset, const hsize_t size[], hid_t dxpl_id, void **req);
+static herr_t H5VL_native_dataset_get(void *dset, H5VL_dataset_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+static herr_t H5VL_native_dataset_close(void *dset, hid_t dxpl_id, void **req);
 
 /* File callbacks */
-static void *H5VL_native_file_create(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t req);
-static void *H5VL_native_file_open(const char *name, unsigned flags, hid_t fapl_id, hid_t req);
-static herr_t H5VL_native_file_flush(void *obj, H5VL_loc_params_t loc_params, H5F_scope_t scope, hid_t req);
-static herr_t H5VL_native_file_get(void *file, H5VL_file_get_t get_type, hid_t req, va_list arguments);
-static herr_t H5VL_native_file_misc(void *file, H5VL_file_misc_t misc_type, hid_t req, va_list arguments);
-static herr_t H5VL_native_file_optional(void *file, H5VL_file_optional_t optional_type, hid_t req, va_list arguments);
-static herr_t H5VL_native_file_close(void *file, hid_t req);
+static void *H5VL_native_file_create(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t dxpl_id, void **req);
+static void *H5VL_native_file_open(const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, void **req);
+static herr_t H5VL_native_file_flush(void *obj, H5VL_loc_params_t loc_params, H5F_scope_t scope, hid_t dxpl_id, void **req);
+static herr_t H5VL_native_file_get(void *file, H5VL_file_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+static herr_t H5VL_native_file_misc(void *file, H5VL_file_misc_t misc_type, hid_t dxpl_id, void **req, va_list arguments);
+static herr_t H5VL_native_file_optional(void *file, H5VL_file_optional_t optional_type, hid_t dxpl_id, void **req, va_list arguments);
+static herr_t H5VL_native_file_close(void *file, hid_t dxpl_id, void **req);
 
 /* Group callbacks */
-static void *H5VL_native_group_create(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t req);
-static void *H5VL_native_group_open(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t gapl_id, hid_t req);
-static herr_t H5VL_native_group_get(void *obj, H5VL_group_get_t get_type, hid_t req, va_list arguments);
-static herr_t H5VL_native_group_close(void *grp, hid_t req);
+static void *H5VL_native_group_create(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, void **req);
+static void *H5VL_native_group_open(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t gapl_id, hid_t dxpl_id, void **req);
+static herr_t H5VL_native_group_get(void *obj, H5VL_group_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+static herr_t H5VL_native_group_close(void *grp, hid_t dxpl_id, void **req);
 
 /* Link callbacks */
 static herr_t H5VL_native_link_create(H5VL_link_create_type_t create_type, void *obj, 
-                                      H5VL_loc_params_t loc_params, hid_t lcpl_id, hid_t lapl_id, hid_t req);
+                                      H5VL_loc_params_t loc_params, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
 static herr_t H5VL_native_link_move(void *src_obj, H5VL_loc_params_t loc_params1,
                                     void *dst_obj, H5VL_loc_params_t loc_params2,
-                                    hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t req);
+                                    hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
 static herr_t H5VL_native_link_iterate(void *obj, H5VL_loc_params_t loc_params, hbool_t recursive, 
                                        H5_index_t idx_type, H5_iter_order_t order, hsize_t *idx, 
-                                       H5L_iterate_t op, void *op_data, hid_t req);
-static herr_t H5VL_native_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_link_get_t get_type, hid_t req, va_list arguments);
-static herr_t H5VL_native_link_remove(void *obj, H5VL_loc_params_t loc_params, hid_t req);
+                                       H5L_iterate_t op, void *op_data, hid_t dxpl_id, void **req);
+static herr_t H5VL_native_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_link_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+static herr_t H5VL_native_link_remove(void *obj, H5VL_loc_params_t loc_params, hid_t dxpl_id, void **req);
 
 /* Object callbacks */
-static void *H5VL_native_object_open(void *obj, H5VL_loc_params_t loc_params, H5I_type_t *opened_type, hid_t req);
+static void *H5VL_native_object_open(void *obj, H5VL_loc_params_t loc_params, H5I_type_t *opened_type, hid_t dxpl_id, void **req);
 static herr_t H5VL_native_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, const char *src_name, 
                                       void *dst_obj, H5VL_loc_params_t loc_params2, const char *dst_name, 
-                                      hid_t ocpypl_id, hid_t lcpl_id, hid_t req);
+                                      hid_t ocpypl_id, hid_t lcpl_id, hid_t dxpl_id, void **req);
 static herr_t H5VL_native_object_visit(void *obj, H5VL_loc_params_t loc_params, H5_index_t idx_type, 
-                                       H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t req);
-//static herr_t H5VL_native_object_lookup(hid_t loc_id, H5VL_loc_type_t lookup_type, void **location, hid_t req, va_list arguments);
-//static herr_t H5VL_native_object_free_loc(void *location, hid_t req);
-static herr_t H5VL_native_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_object_get_t get_type, hid_t req, va_list arguments);
-static herr_t H5VL_native_object_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_object_misc_t misc_type, hid_t req, va_list arguments);
-static herr_t H5VL_native_object_optional(void *obj, H5VL_loc_params_t loc_params, H5VL_object_optional_t optional_type, hid_t req, va_list arguments);
-static herr_t H5VL_native_object_close(void *obj, H5VL_loc_params_t loc_params, hid_t req);
+                                       H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t dxpl_id, void **req);
+static herr_t H5VL_native_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_object_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+static herr_t H5VL_native_object_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_object_misc_t misc_type, hid_t dxpl_id, void **req, va_list arguments);
+static herr_t H5VL_native_object_optional(void *obj, H5VL_loc_params_t loc_params, H5VL_object_optional_t optional_type, hid_t dxpl_id, void **req, va_list arguments);
+static herr_t H5VL_native_object_close(void *obj, H5VL_loc_params_t loc_params, hid_t dxpl_id, void **req);
 
 static H5VL_class_t H5VL_native_g = {
     NATIVE,
@@ -190,6 +188,11 @@ static H5VL_class_t H5VL_native_g = {
         H5VL_native_object_misc,                /* misc */
         H5VL_native_object_optional,            /* optional */
         H5VL_native_object_close                /* close */
+    },
+    {                                           /* async_cls */
+        NULL,                                   /* cancel */
+        NULL,                                   /* test */
+        NULL                                    /* wait */
     }
 };
 
@@ -425,7 +428,7 @@ done:
  */
 static void *
 H5VL_native_attr_create(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t acpl_id, 
-                        hid_t UNUSED aapl_id, hid_t UNUSED req)
+                        hid_t UNUSED aapl_id, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t       loc;                /* Object location */
     H5G_loc_t       obj_loc;            /* Location used to open group */
@@ -515,7 +518,7 @@ done:
  */
 static void *
 H5VL_native_attr_open(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, 
-                      hid_t UNUSED aapl_id, hid_t UNUSED req)
+                      hid_t UNUSED aapl_id, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t    loc;             /* Object location */
     H5A_t        *attr = NULL;    /* Attribute opened */
@@ -574,7 +577,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_attr_read(void *attr, hid_t dtype_id, void *buf, hid_t UNUSED req)
+H5VL_native_attr_read(void *attr, hid_t dtype_id, void *buf, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5T_t *mem_type;            /* Memory datatype */
     herr_t ret_value;           /* Return value */
@@ -605,7 +608,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_attr_write(void *attr, hid_t dtype_id, const void *buf, hid_t UNUSED req)
+H5VL_native_attr_write(void *attr, hid_t dtype_id, const void *buf, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5T_t *mem_type;            /* Memory datatype */
     herr_t ret_value;           /* Return value */
@@ -637,7 +640,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_attr_get(void *obj, H5VL_attr_get_t get_type, hid_t UNUSED req, va_list arguments)
+H5VL_native_attr_get(void *obj, H5VL_attr_get_t get_type, hid_t UNUSED dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t      ret_value = SUCCEED;    /* Return value */
 
@@ -851,7 +854,7 @@ done:
  */
 static herr_t 
 H5VL_native_attr_remove(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, 
-                        hid_t UNUSED req)
+                        hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t   loc;                    /* Object location */
     H5G_loc_t   obj_loc;                /* Location used to open group */
@@ -932,7 +935,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_attr_close(void *attr, hid_t UNUSED req)
+H5VL_native_attr_close(void *attr, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     herr_t ret_value = SUCCEED;                 /* Return value */
 
@@ -961,7 +964,7 @@ done:
  */
 static void *
 H5VL_native_datatype_commit(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t type_id, 
-                            hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t UNUSED req)
+                            hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t	loc;                    /* Location to commit datatype */
     H5T_t	*dt;                    /* Datatype for ID */
@@ -1042,7 +1045,7 @@ done:
  */
 static void *
 H5VL_native_datatype_open(void *obj, H5VL_loc_params_t loc_params, const char *name, 
-                          hid_t tapl_id, hid_t UNUSED req)
+                          hid_t tapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     H5T_t       *type = NULL;           /* Datatype opened in file */
     H5G_loc_t	 loc;                   /* Group location of object to open */
@@ -1051,7 +1054,6 @@ H5VL_native_datatype_open(void *obj, H5VL_loc_params_t loc_params, const char *n
     H5O_type_t   obj_type;              /* Type of object at location */
     H5G_loc_t    type_loc;              /* Group object for datatype */
     hbool_t      obj_found = FALSE;     /* Object at 'name' found */
-    hid_t        dxpl_id = H5AC_dxpl_id; /* dxpl to use to open datatype */
     void        *ret_value = NULL;
 
     FUNC_ENTER_NOAPI_NOINIT
@@ -1105,7 +1107,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static ssize_t
-H5VL_native_datatype_get_binary(void *obj, unsigned char *buf, size_t size, hid_t UNUSED req)
+H5VL_native_datatype_get_binary(void *obj, unsigned char *buf, size_t size, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5T_t       *type = (H5T_t *)obj;
     size_t       nalloc = size;
@@ -1137,7 +1139,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_datatype_close(void *dt, hid_t UNUSED req)
+H5VL_native_datatype_close(void *dt, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     herr_t ret_value = SUCCEED;                 /* Return value */
 
@@ -1166,7 +1168,7 @@ done:
  */
 static void *
 H5VL_native_dataset_create(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t dcpl_id, 
-                           hid_t dapl_id, hid_t UNUSED req)
+                           hid_t dapl_id, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5P_genplist_t *plist;              /* Property list pointer */
     H5G_loc_t	   loc;                 /* Object location to insert dataset into */
@@ -1246,7 +1248,7 @@ done:
  */
 static void *
 H5VL_native_dataset_open(void *obj, H5VL_loc_params_t loc_params, const char *name, 
-                         hid_t dapl_id, hid_t UNUSED req)
+                         hid_t dapl_id, hid_t dxpl_id, void UNUSED **req)
 {
     H5D_t       *dset = NULL;
     H5G_loc_t	 loc;		        /* Object location of group */
@@ -1255,7 +1257,6 @@ H5VL_native_dataset_open(void *obj, H5VL_loc_params_t loc_params, const char *na
     H5O_loc_t    oloc;            	/* Dataset object location */
     H5O_type_t   obj_type;              /* Type of object at location */
     hbool_t      loc_found = FALSE;     /* Location at 'name' found */
-    hid_t        dxpl_id = H5AC_dxpl_id;    /* dxpl to use to open datset */
     void         *ret_value = NULL;
 
     FUNC_ENTER_NOAPI_NOINIT
@@ -1307,7 +1308,7 @@ done:
  */
 static herr_t
 H5VL_native_dataset_read(void *obj, hid_t mem_type_id, hid_t mem_space_id,
-                         hid_t file_space_id, hid_t plist_id, void *buf, hid_t UNUSED req)
+                         hid_t file_space_id, hid_t plist_id, void *buf, void UNUSED **req)
 {
     H5D_t         *dset = (H5D_t *)obj;
     const H5S_t   *mem_space = NULL;
@@ -1372,7 +1373,7 @@ done:
  */
 static herr_t
 H5VL_native_dataset_write(void *obj, hid_t mem_type_id, hid_t mem_space_id,
-                          hid_t file_space_id, hid_t dxpl_id, const void *buf, hid_t UNUSED req)
+                          hid_t file_space_id, hid_t dxpl_id, const void *buf, void UNUSED **req)
 {
     H5D_t         *dset = (H5D_t *)obj;
     const H5S_t   *mem_space = NULL;
@@ -1435,7 +1436,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t 
-H5VL_native_dataset_set_extent(void *obj, const hsize_t size[], hid_t UNUSED req)
+H5VL_native_dataset_set_extent(void *obj, const hsize_t size[], hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5D_t         *dset = (H5D_t *)obj;
     herr_t       ret_value = SUCCEED;    /* Return value */
@@ -1465,7 +1466,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_dataset_get(void *obj, H5VL_dataset_get_t get_type, hid_t UNUSED req, va_list arguments)
+H5VL_native_dataset_get(void *obj, H5VL_dataset_get_t get_type, hid_t UNUSED dxpl_id, void UNUSED **req, va_list arguments)
 {
     H5D_t       *dset = (H5D_t *)obj;
     herr_t       ret_value = SUCCEED;    /* Return value */
@@ -1568,7 +1569,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_dataset_close(void *dset, hid_t UNUSED req)
+H5VL_native_dataset_close(void *dset, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     herr_t ret_value = SUCCEED;                 /* Return value */
 
@@ -1597,7 +1598,7 @@ done:
  */
 static void *
 H5VL_native_file_create(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, 
-                        hid_t UNUSED req)
+                        hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5F_t *new_file = NULL;
     void  *ret_value = NULL;
@@ -1642,7 +1643,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static void *
-H5VL_native_file_open(const char *name, unsigned flags, hid_t fapl_id, hid_t UNUSED req)
+H5VL_native_file_open(const char *name, unsigned flags, hid_t fapl_id, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5F_t *new_file = NULL;
     void  *ret_value = NULL;
@@ -1677,7 +1678,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_file_flush(void *obj, H5VL_loc_params_t loc_params, H5F_scope_t scope, hid_t UNUSED req)
+H5VL_native_file_flush(void *obj, H5VL_loc_params_t loc_params, H5F_scope_t scope, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5F_t	*f = NULL;              /* File to flush */
     herr_t      ret_value = SUCCEED;    /* Return value */
@@ -1729,7 +1730,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_file_get(void *obj, H5VL_file_get_t get_type, hid_t UNUSED req, va_list arguments)
+H5VL_native_file_get(void *obj, H5VL_file_get_t get_type, hid_t UNUSED dxpl_id, void UNUSED **req, va_list arguments)
 {
     H5F_t *f = NULL;  /* File struct */
     herr_t      ret_value = SUCCEED;    /* Return value */
@@ -1883,7 +1884,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_file_misc(void *obj, H5VL_file_misc_t misc_type, hid_t UNUSED req, va_list arguments)
+H5VL_native_file_misc(void *obj, H5VL_file_misc_t misc_type, hid_t UNUSED dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t       ret_value = SUCCEED;    /* Return value */
 
@@ -1959,7 +1960,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_file_optional(void *obj, H5VL_file_optional_t optional_type, hid_t UNUSED req, va_list arguments)
+H5VL_native_file_optional(void *obj, H5VL_file_optional_t optional_type, hid_t UNUSED dxpl_id, void UNUSED **req, va_list arguments)
 {
     H5F_t        *f = NULL;           /* File */
     herr_t       ret_value = SUCCEED;    /* Return value */
@@ -2179,7 +2180,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_file_close(void *file, hid_t UNUSED req)
+H5VL_native_file_close(void *file, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     int nref;
     H5F_t *f = (H5F_t *)file;
@@ -2227,7 +2228,7 @@ done:
  */
 static void *
 H5VL_native_group_create(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t gcpl_id, 
-                         hid_t gapl_id, hid_t UNUSED req)
+                         hid_t gapl_id, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5P_genplist_t *plist;              /* Property list pointer */
     H5G_loc_t      loc;                 /* Location to create group */
@@ -2301,7 +2302,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static void *
-H5VL_native_group_open(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t gapl_id, hid_t UNUSED req)
+H5VL_native_group_open(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t gapl_id, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t	    loc;                /* Location to open group */
     H5G_t	   *grp = NULL;         /* New group opend */
@@ -2337,7 +2338,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_group_get(void *obj, H5VL_group_get_t get_type, hid_t UNUSED req, va_list arguments)
+H5VL_native_group_get(void *obj, H5VL_group_get_t get_type, hid_t UNUSED dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t      ret_value = SUCCEED;    /* Return value */
 
@@ -2451,7 +2452,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_group_close(void *grp, hid_t UNUSED req)
+H5VL_native_group_close(void *grp, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     herr_t ret_value = SUCCEED;                 /* Return value */
 
@@ -2479,7 +2480,7 @@ done:
  */
 static herr_t
 H5VL_native_link_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params,
-                        hid_t lcpl_id, hid_t lapl_id, hid_t UNUSED req)
+                        hid_t lcpl_id, hid_t lapl_id, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5P_genplist_t   *plist;                     /* Property list pointer */
     herr_t           ret_value = SUCCEED;        /* Return value */
@@ -2604,7 +2605,7 @@ done:
 static herr_t
 H5VL_native_link_move(void *src_obj, H5VL_loc_params_t loc_params1, 
                       void *dst_obj, H5VL_loc_params_t loc_params2,
-                      hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t UNUSED req)
+                      hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t	src_loc, *src_loc_p;
     H5G_loc_t	dst_loc, *dst_loc_p;
@@ -2651,7 +2652,7 @@ done:
  */
 static herr_t H5VL_native_link_iterate(void *obj, H5VL_loc_params_t loc_params, hbool_t recursive, 
                                        H5_index_t idx_type, H5_iter_order_t order, hsize_t *idx_p, 
-                                       H5L_iterate_t op, void *op_data, hid_t UNUSED req)
+                                       H5L_iterate_t op, void *op_data, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t	loc;
     herr_t ret_value;           /* Return value */
@@ -2732,7 +2733,7 @@ done:
  */
 static herr_t
 H5VL_native_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_link_get_t get_type, 
-                     hid_t UNUSED req, va_list arguments)
+                     hid_t UNUSED dxpl_id, void UNUSED **req, va_list arguments)
 {
     H5G_loc_t	loc;
     herr_t      ret_value = SUCCEED;    /* Return value */
@@ -2866,7 +2867,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t 
-H5VL_native_link_remove(void *obj, H5VL_loc_params_t loc_params, hid_t UNUSED req)
+H5VL_native_link_remove(void *obj, H5VL_loc_params_t loc_params, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t       loc;                /* Object location */
     herr_t ret_value = SUCCEED;
@@ -2917,7 +2918,7 @@ done:
  */
 static void *
 H5VL_native_object_open(void *obj, H5VL_loc_params_t loc_params, H5I_type_t *opened_type, 
-                        hid_t UNUSED req)
+                        hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t   loc;
     H5G_loc_t   obj_loc;                /* Location used to open group */
@@ -3032,7 +3033,7 @@ done:
 static herr_t 
 H5VL_native_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, const char *src_name, 
                         void *dst_obj, H5VL_loc_params_t loc_params2, const char *dst_name, 
-                        hid_t ocpypl_id, hid_t lcpl_id, hid_t UNUSED req)
+                        hid_t ocpypl_id, hid_t lcpl_id, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t	src_loc;                /* Source object group location */
     H5G_loc_t	dst_loc;                /* Destination group location */
@@ -3070,7 +3071,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t H5VL_native_object_visit(void *obj, H5VL_loc_params_t loc_params, H5_index_t idx_type,
-                                       H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t UNUSED req)
+                                       H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t    loc;
     herr_t ret_value;           /* Return value */
@@ -3116,7 +3117,7 @@ done:
  */
 static herr_t
 H5VL_native_object_lookup(hid_t loc_id, H5VL_loc_type_t lookup_type, void **loc_token, 
-                          hid_t UNUSED req, va_list arguments)
+                          hid_t UNUSED dxpl_id, void UNUSED **req, va_list arguments)
 {
     H5G_loc_t	loc;
     H5G_loc_t   *obj_loc;
@@ -3253,7 +3254,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t 
-H5VL_native_object_free_loc(void *location, hid_t UNUSED req)
+H5VL_native_object_free_loc(void *location, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     H5G_loc_t   *obj_loc = (H5G_loc_t *)location;
     herr_t      ret_value = SUCCEED;    /* Return value */
@@ -3294,7 +3295,7 @@ done:
  */
 static herr_t
 H5VL_native_object_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_object_misc_t misc_type, 
-                        hid_t UNUSED req, va_list arguments)
+                        hid_t UNUSED dxpl_id, void UNUSED **req, va_list arguments)
 {
     H5G_loc_t    loc;
     herr_t       ret_value = SUCCEED;    /* Return value */
@@ -3405,7 +3406,7 @@ done:
  */
 static herr_t
 H5VL_native_object_optional(void UNUSED *obj, H5VL_loc_params_t UNUSED loc_params, 
-                            H5VL_object_optional_t optional_type, hid_t UNUSED req, va_list UNUSED arguments)
+                            H5VL_object_optional_t optional_type, hid_t UNUSED dxpl_id, void UNUSED **req, va_list UNUSED arguments)
 {
     herr_t       ret_value = SUCCEED;    /* Return value */
 
@@ -3437,7 +3438,7 @@ done:
  */
 static herr_t
 H5VL_native_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_object_get_t get_type, 
-                       hid_t UNUSED req, va_list arguments)
+                       hid_t UNUSED dxpl_id, void UNUSED **req, va_list arguments)
 {
     herr_t      ret_value = SUCCEED;    /* Return value */
     H5G_loc_t	loc;                    /* Location of group */
@@ -3605,7 +3606,7 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5VL_native_object_close(void UNUSED *obj, H5VL_loc_params_t loc_params, hid_t UNUSED req)
+H5VL_native_object_close(void UNUSED *obj, H5VL_loc_params_t loc_params, hid_t UNUSED dxpl_id, void UNUSED **req)
 {
     herr_t ret_value = SUCCEED;                 /* Return value */
 
diff --git a/src/H5VLprivate.h b/src/H5VLprivate.h
index ed3719f..b42ebb1 100644
--- a/src/H5VLprivate.h
+++ b/src/H5VLprivate.h
@@ -29,7 +29,8 @@
 /****************************/
 /* Library Private Typedefs */
 /****************************/
-#define H5_REQUEST_NULL -1
+#define H5_REQUEST_NULL NULL
+#define H5_EVENT_QUEUE_NULL -1
 
 /*****************************/
 /* Library Private Variables */
@@ -51,61 +52,65 @@ H5_DLL ssize_t H5VL_get_plugin_name(hid_t id, char *name/*out*/, size_t size);
 H5_DLL void *H5VL_get_object(hid_t id);
 H5_DLL herr_t H5VL_close(H5VL_class_t *vol_plugin);
 
-H5_DLL void *H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t req);
-H5_DLL void *H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t aapl_id, hid_t req);
-H5_DLL herr_t H5VL_attr_read(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, void *buf, hid_t req);
-H5_DLL herr_t H5VL_attr_write(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, const void *buf, hid_t req);
-H5_DLL herr_t H5VL_attr_get(void *attr, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req, ...);
-H5_DLL herr_t H5VL_attr_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,  const char *attr_name, hid_t req);
-H5_DLL herr_t H5VL_attr_close(void *attr, H5VL_t *vol_plugin, hid_t req);
-
-H5_DLL void *H5VL_dataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t req);
-H5_DLL void *H5VL_dataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dapl_id, hid_t req);
-H5_DLL herr_t H5VL_dataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, void *buf, hid_t req);
-H5_DLL herr_t H5VL_dataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, const void *buf, hid_t req);
-H5_DLL herr_t H5VL_dataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], hid_t req);
-H5_DLL herr_t H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid_t req, ...);
-H5_DLL herr_t H5VL_dataset_close(void *dset, H5VL_t *vol_plugin, hid_t req);
-
-H5_DLL void *H5VL_datatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t req);
-H5_DLL void *H5VL_datatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t tapl_id, hid_t req);
-H5_DLL ssize_t H5VL_datatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size_t size, hid_t req);
-H5_DLL herr_t H5VL_datatype_close(void *dt, H5VL_t *vol_plugin, hid_t req);
-
-H5_DLL void *H5VL_file_create(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t req);
-H5_DLL void *H5VL_file_open(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fapl_id, hid_t req);
-H5_DLL herr_t H5VL_file_flush(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5F_scope_t scope, hid_t req);
-H5_DLL herr_t H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t req, ...);
-H5_DLL herr_t H5VL_file_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_type, hid_t req, ...);
-H5_DLL herr_t H5VL_file_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req, ...);
-H5_DLL herr_t H5VL_file_close(void *file, H5VL_t *vol_plugin, hid_t req);
-
-H5_DLL void *H5VL_group_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t req);
-H5_DLL void *H5VL_group_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gapl_id, hid_t req);
-H5_DLL herr_t H5VL_group_close(void *grp, H5VL_t *vol_plugin, hid_t req);
-H5_DLL herr_t H5VL_group_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t req, ...);
-
-H5_DLL herr_t H5VL_link_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t req);
+H5_DLL void *H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, hid_t event_q);
+H5_DLL void *H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t aapl_id, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_attr_read(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, void *buf, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_attr_write(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, const void *buf, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_attr_get(void *attr, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t dxpl_id, hid_t event_q, ...);
+H5_DLL herr_t H5VL_attr_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,  const char *attr_name, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_attr_close(void *attr, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t event_q);
+
+H5_DLL void *H5VL_dataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, hid_t event_q);
+H5_DLL void *H5VL_dataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dapl_id, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_dataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, void *buf, hid_t event_q);
+H5_DLL herr_t H5VL_dataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, const void *buf, hid_t event_q);
+H5_DLL herr_t H5VL_dataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid_t dxpl_id, hid_t event_q, ...);
+H5_DLL herr_t H5VL_dataset_close(void *dset, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t event_q);
+
+H5_DLL void *H5VL_datatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t dxpl_id, hid_t event_q);
+H5_DLL void *H5VL_datatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t tapl_id, hid_t dxpl_id, hid_t event_q);
+H5_DLL ssize_t H5VL_datatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size_t size, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_datatype_close(void *dt, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t event_q);
+
+H5_DLL void *H5VL_file_create(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t dxpl_id, hid_t event_q);
+H5_DLL void *H5VL_file_open(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_file_flush(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5F_scope_t scope, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_file_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t dxpl_id, hid_t event_q, ...);
+H5_DLL herr_t H5VL_file_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_type, hid_t dxpl_id, hid_t event_q, ...);
+H5_DLL herr_t H5VL_file_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t dxpl_id, hid_t event_q, ...);
+H5_DLL herr_t H5VL_file_close(void *file, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t event_q);
+
+H5_DLL void *H5VL_group_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, hid_t event_q);
+H5_DLL void *H5VL_group_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gapl_id, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_group_close(void *grp, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_group_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t dxpl_id, hid_t event_q, ...);
+
+H5_DLL herr_t H5VL_link_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, hid_t event_q);
 H5_DLL herr_t H5VL_link_move(void *src_obj, H5VL_loc_params_t loc_params1,
                              void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin,
-                             hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t req);
+                             hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, hid_t event_q);
 H5_DLL herr_t H5VL_link_iterate(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
                                 hbool_t recursive, H5_index_t idx_type, H5_iter_order_t order, 
-                                hsize_t *idx, H5L_iterate_t op, void *op_data, hid_t req);
-H5_DLL herr_t H5VL_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_get_t get_type, hid_t req, ...);
-H5_DLL herr_t H5VL_link_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t req);
+                                hsize_t *idx, H5L_iterate_t op, void *op_data, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_get_t get_type, hid_t dxpl_id, hid_t event_q, ...);
+H5_DLL herr_t H5VL_link_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t event_q);
 
-H5_DLL void *H5VL_object_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5I_type_t *opened_type, hid_t req);
+H5_DLL void *H5VL_object_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5I_type_t *opened_type, hid_t dxpl_id, hid_t event_q);
 H5_DLL herr_t H5VL_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugin1, const char *src_name, 
                                void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin2, const char *dst_name, 
-                               hid_t ocpypl_id, hid_t lcpl_id, hid_t req);
-H5_DLL herr_t H5VL_object_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5_index_t idx_type, H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t req);
-H5_DLL herr_t H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, hid_t req, ...);
-H5_DLL herr_t H5VL_object_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t misc_type, hid_t req, ...);
-H5_DLL herr_t H5VL_object_optional(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t optional_type, hid_t req, ...);
-//H5_DLL herr_t H5VL_object_lookup(hid_t uid, H5VL_loc_type_t lookup_type, void **location, hid_t req, ...);
-//H5_DLL herr_t H5VL_object_free_loc(hid_t loc_id, void *location, hid_t req);
-H5_DLL herr_t H5VL_object_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t req);
+                               hid_t ocpypl_id, hid_t lcpl_id, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_object_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5_index_t idx_type, H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, hid_t dxpl_id, hid_t event_q, ...);
+H5_DLL herr_t H5VL_object_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t misc_type, hid_t dxpl_id, hid_t event_q, ...);
+H5_DLL herr_t H5VL_object_optional(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t optional_type, hid_t dxpl_id, hid_t event_q, ...);
+//H5_DLL herr_t H5VL_object_lookup(hid_t uid, H5VL_loc_type_t lookup_type, void **location, hid_t dxpl_id, hid_t event_q, ...);
+//H5_DLL herr_t H5VL_object_free_loc(hid_t loc_id, void *location, hid_t dxpl_id, hid_t event_q);
+H5_DLL herr_t H5VL_object_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t dxpl_id, hid_t event_q);
+
+H5_DLL herr_t H5VL_request_cancel(void **req, H5VL_t *vol_plugin, H5_status_t *status);
+H5_DLL herr_t H5VL_request_test(void **req, H5VL_t *vol_plugin, H5_status_t *status);
+H5_DLL herr_t H5VL_request_wait(void **req, H5VL_t *vol_plugin, H5_status_t *status);
 
 H5_DLL herr_t H5VL_fapl_open(struct H5P_genplist_t *plist, H5VL_class_t *vol_cls, const void *vol_info);
 H5_DLL herr_t H5VL_fapl_copy(H5VL_class_t *vol_cls, const void *vol_info, void **copied_info);
diff --git a/src/H5VLpublic.h b/src/H5VLpublic.h
index 670a5b7..854c21f 100644
--- a/src/H5VLpublic.h
+++ b/src/H5VLpublic.h
@@ -28,6 +28,14 @@
 #include "H5Opublic.h"
 #include "H5Rpublic.h"
 
+/* Asynchronous operation status */
+typedef enum {
+    H5AO_PENDING,       /* Operation has not yet completed */
+    H5AO_SUCCEEDED,     /* Operation has completed, successfully */
+    H5AO_FAILED,        /* Operation has completed, but failed */
+    H5AO_CANCELLED      /* Operation has no completed and has been cancelled */
+} H5_status_t;
+
 /* Dataset creation property names */
 #define H5VL_DSET_TYPE_ID        "dataset_type_id"
 #define H5VL_DSET_SPACE_ID       "dataset_space_id"
@@ -202,87 +210,94 @@ typedef struct H5VL_t H5VL_t;
 
 /* H5A routines */
 typedef struct H5VL_attr_class_t {
-    void  *(*create)(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t req);
-    void  *(*open)  (void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t aapl_id, hid_t req);
-    herr_t (*read)  (void *attr, hid_t mem_type_id, void *buf, hid_t req);
-    herr_t (*write) (void *attr, hid_t mem_type_id, const void *buf, hid_t req);
-    herr_t (*get)   (void *attr, H5VL_attr_get_t get_type, hid_t req, va_list arguments);
-    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t req);
-    herr_t (*close) (void *attr, hid_t req);
+    void  *(*create)(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req);
+    void  *(*open)  (void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t aapl_id, hid_t dxpl_id, void **req);
+    herr_t (*read)  (void *attr, hid_t mem_type_id, void *buf, hid_t dxpl_id, void **req);
+    herr_t (*write) (void *attr, hid_t mem_type_id, const void *buf, hid_t dxpl_id, void **req);
+    herr_t (*get)   (void *attr, H5VL_attr_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, const char *attr_name, hid_t dxpl_id, void **req);
+    herr_t (*close) (void *attr, hid_t dxpl_id, void **req);
 } H5VL_attr_class_t;
 
 /* H5T routines*/
 typedef struct H5VL_datatype_class_t {
     void  *(*commit)(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t type_id, 
-                     hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t req);
-    void  *(*open)  (void *obj, H5VL_loc_params_t loc_params, const char * name, hid_t tapl_id, hid_t req);
-    ssize_t (*get_binary) (void *obj, unsigned char *buf, size_t size, hid_t req);
-    herr_t (*close) (void *dt, hid_t req);
+                     hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t dxpl_id, void **req);
+    void  *(*open)  (void *obj, H5VL_loc_params_t loc_params, const char * name, hid_t tapl_id, hid_t dxpl_id, void **req);
+    ssize_t (*get_binary) (void *obj, unsigned char *buf, size_t size, hid_t dxpl_id, void **req);
+    herr_t (*close) (void *dt, hid_t dxpl_id, void **req);
 } H5VL_datatype_class_t;
 
 /* H5D routines */
 typedef struct H5VL_dataset_class_t {
-    void  *(*create)(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t req);
-    void  *(*open)  (void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t dapl_id, hid_t req);
+    void  *(*create)(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, void **req);
+    void  *(*open)  (void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t dapl_id, hid_t dxpl_id, void **req);
     herr_t (*read)  (void *dset, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id,
-                     hid_t xfer_plist_id, void * buf, hid_t req);
+                     hid_t xfer_plist_id, void * buf, void **req);
     herr_t (*write) (void *dset, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id,
-                     hid_t xfer_plist_id, const void * buf, hid_t req);
-    herr_t (*set_extent) (void *dset, const hsize_t size[], hid_t req);
-    herr_t (*get)   (void *dset, H5VL_dataset_get_t get_type, hid_t req, va_list arguments);
-    herr_t (*close) (void *dset, hid_t req);
+                     hid_t xfer_plist_id, const void * buf, void **req);
+    herr_t (*set_extent) (void *dset, const hsize_t size[], hid_t dxpl_id, void **req);
+    herr_t (*get)   (void *dset, H5VL_dataset_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*close) (void *dset, hid_t dxpl_id, void **req);
 } H5VL_dataset_class_t;
 
 /* H5F routines */
 typedef struct H5VL_file_class_t {
     void  *(*create)(const char *name, unsigned flags, hid_t fcpl_id, 
-                     hid_t fapl_id, hid_t req);
-    void  *(*open)  (const char *name, unsigned flags, hid_t fapl_id, hid_t req);
-    herr_t (*flush) (void *obj, H5VL_loc_params_t loc_params, H5F_scope_t scope, hid_t req);
-    herr_t (*get)   (void *file, H5VL_file_get_t get_type, hid_t req, va_list arguments);
-    herr_t (*misc)  (void *file, H5VL_file_misc_t misc_type, hid_t req, va_list arguments);
-    herr_t (*optional)(void *file, H5VL_file_optional_t op_type, hid_t req, va_list arguments);
-    herr_t (*close) (void *file, hid_t req);
+                     hid_t fapl_id, hid_t dxpl_id, void **req);
+    void  *(*open)  (const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, void **req);
+    herr_t (*flush) (void *obj, H5VL_loc_params_t loc_params, H5F_scope_t scope, hid_t dxpl_id, void **req);
+    herr_t (*get)   (void *file, H5VL_file_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*misc)  (void *file, H5VL_file_misc_t misc_type, hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*optional)(void *file, H5VL_file_optional_t op_type, hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*close) (void *file, hid_t dxpl_id, void **req);
 } H5VL_file_class_t;
 
 /* H5G routines */
 typedef struct H5VL_group_class_t {
-    void  *(*create)(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t req);
-    void  *(*open)  (void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t gapl_id, hid_t req);
-    herr_t (*get)   (void *obj, H5VL_group_get_t get_type, hid_t req, va_list arguments);
-    herr_t (*close) (void *grp, hid_t req);
+    void  *(*create)(void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, void **req);
+    void  *(*open)  (void *obj, H5VL_loc_params_t loc_params, const char *name, hid_t gapl_id, hid_t dxpl_id, void **req);
+    herr_t (*get)   (void *obj, H5VL_group_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*close) (void *grp, hid_t dxpl_id, void **req);
 } H5VL_group_class_t;
 
 /* H5L routines */
 typedef struct H5VL_link_class_t {
     herr_t (*create)(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, 
-                     hid_t lcpl_id, hid_t lapl_id, hid_t req);
+                     hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
     herr_t (*move)  (void *src_obj, H5VL_loc_params_t loc_params1, 
                      void *dst_obj, H5VL_loc_params_t loc_params2,
-                     hbool_t copy_flag, hid_t lcpl, hid_t lapl, hid_t req);
+                     hbool_t copy_flag, hid_t lcpl, hid_t lapl, hid_t dxpl_id, void **req);
     herr_t (*iterate) (void *obj, H5VL_loc_params_t loc_params, hbool_t recursive, 
                        H5_index_t idx_type, H5_iter_order_t order, hsize_t *idx, 
-                       H5L_iterate_t op, void *op_data, hid_t req);
-    herr_t (*get)   (void *obj, H5VL_loc_params_t loc_params, H5VL_link_get_t get_type, hid_t req, va_list arguments);
-    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, hid_t req);
+                       H5L_iterate_t op, void *op_data, hid_t dxpl_id, void **req);
+    herr_t (*get)   (void *obj, H5VL_loc_params_t loc_params, H5VL_link_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, hid_t dxpl_id, void **req);
 } H5VL_link_class_t;
 
 /* H5O routines */
 typedef struct H5VL_object_class_t {
-    void  *(*open)  (void *obj, H5VL_loc_params_t loc_params, H5I_type_t *opened_type, hid_t req);
+    void  *(*open)  (void *obj, H5VL_loc_params_t loc_params, H5I_type_t *opened_type, hid_t dxpl_id, void **req);
     herr_t (*copy)  (void *src_obj, H5VL_loc_params_t loc_params1, const char *src_name, 
                      void *dst_obj, H5VL_loc_params_t loc_params2, const char *dst_name,
-                     hid_t ocpypl_id, hid_t lcpl_id, hid_t req);
+                     hid_t ocpypl_id, hid_t lcpl_id, hid_t dxpl_id, void **req);
     herr_t (*visit) (void *obj, H5VL_loc_params_t loc_params, H5_index_t idx_type,
-                     H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t req);
-    //herr_t (*lookup)(hid_t loc_id, H5VL_loc_type_t lookup_type, void **location, hid_t req, va_list arguments);
-    //herr_t (*free_loc)(void *location, hid_t req);
-    herr_t (*get)   (void *obj, H5VL_loc_params_t loc_params, H5VL_object_get_t get_type, hid_t req, va_list arguments);
-    herr_t (*misc)  (void *obj, H5VL_loc_params_t loc_params, H5VL_object_misc_t misc_type, hid_t req, va_list arguments);
-    herr_t (*optional)(void *obj, H5VL_loc_params_t loc_params, H5VL_object_optional_t op_type, hid_t req, va_list arguments);
-    herr_t (*close) (void *obj, H5VL_loc_params_t loc_params, hid_t req);
+                     H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t dxpl_id, void **req);
+    //herr_t (*lookup)(hid_t loc_id, H5VL_loc_type_t lookup_type, void **location, hid_t dxpl_id, void **req, va_list arguments);
+    //herr_t (*free_loc)(void *location, hid_t dxpl_id, void **req);
+    herr_t (*get)   (void *obj, H5VL_loc_params_t loc_params, H5VL_object_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*misc)  (void *obj, H5VL_loc_params_t loc_params, H5VL_object_misc_t misc_type, hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*optional)(void *obj, H5VL_loc_params_t loc_params, H5VL_object_optional_t op_type, hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*close) (void *obj, H5VL_loc_params_t loc_params, hid_t dxpl_id, void **req);
 } H5VL_object_class_t;
 
+/* H5AO routines */
+typedef struct H5VL_async_class_t {
+    herr_t (*cancel)(void **, H5_status_t *);
+    herr_t (*test)  (void **, H5_status_t *);
+    herr_t (*wait)  (void **, H5_status_t *);
+} H5VL_async_class_t;
+
 /* enum value to identify the class of a VOL plugin (mostly for comparison purposes */
 typedef enum H5VL_class_value_t {
     NATIVE = 0,
@@ -305,6 +320,7 @@ typedef struct H5VL_class_t {
     H5VL_group_class_t         group_cls;
     H5VL_link_class_t          link_cls;
     H5VL_object_class_t        object_cls;
+    H5VL_async_class_t         async_cls;
 } H5VL_class_t;
 
 /*
@@ -324,65 +340,69 @@ extern "C" {
 #endif
 
 /* ATTRIBUTE OBJECT ROUTINES */
-H5_DLL void *H5VLattr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t req);
-H5_DLL void *H5VLattr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t aapl_id, hid_t req);
-H5_DLL herr_t H5VLattr_read(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, void *buf, hid_t req);
-H5_DLL herr_t H5VLattr_write(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, const void *buf, hid_t req);
-H5_DLL herr_t H5VLattr_get(void *attr, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t req, va_list arguments);
-H5_DLL herr_t H5VLattr_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,  const char *attr_name, hid_t req);
-H5_DLL herr_t H5VLattr_close(void *attr, H5VL_t *vol_plugin, hid_t req);
+H5_DLL void *H5VLattr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VLattr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t aapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLattr_read(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, void *buf, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLattr_write(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, const void *buf, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLattr_get(void *attr, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLattr_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,  const char *attr_name, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLattr_close(void *attr, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
 
 /* DATASE OBJECT ROUTINES */
-H5_DLL void *H5VLdataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t req);
-H5_DLL void *H5VLdataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dapl_id, hid_t req);
-H5_DLL herr_t H5VLdataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, void *buf, hid_t req);
-H5_DLL herr_t H5VLdataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, const void *buf, hid_t req);
-H5_DLL herr_t H5VLdataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], hid_t req);
-H5_DLL herr_t H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid_t req, va_list arguments);
-H5_DLL herr_t H5VLdataset_close(void *dset, H5VL_t *vol_plugin, hid_t req);
+H5_DLL void *H5VLdataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VLdataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLdataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, void *buf, void **req);
+H5_DLL herr_t H5VLdataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, const void *buf, void **req);
+H5_DLL herr_t H5VLdataset_set_extent(void *dset, H5VL_t *vol_plugin, const hsize_t size[], hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLdataset_close(void *dset, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
 
 /* DATATYPE OBJECT ROUTINES */
-H5_DLL void *H5VLdatatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t req);
-H5_DLL void *H5VLdatatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t tapl_id, hid_t req);
-H5_DLL ssize_t H5VLdatatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size_t size, hid_t req);
-H5_DLL herr_t H5VLdatatype_close(void *dt, H5VL_t *vol_plugin, hid_t req);
+H5_DLL void *H5VLdatatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VLdatatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t tapl_id, hid_t dxpl_id, void **req);
+H5_DLL ssize_t H5VLdatatype_get_binary(void *obj, H5VL_t *vol_plugin, unsigned char *buf, size_t size, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLdatatype_close(void *dt, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
 
 /* FILE OBJECT ROUTINES */
-H5_DLL void *H5VLfile_create(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t req);
-H5_DLL void *H5VLfile_open(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fapl_id, hid_t req);
-H5_DLL herr_t H5VLfile_flush(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5F_scope_t scope, hid_t req);
-H5_DLL herr_t H5VLfile_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t req, va_list arguments);
-H5_DLL herr_t H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_type, hid_t req, va_list arguments);
-H5_DLL herr_t H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t req, va_list arguments);
-H5_DLL herr_t H5VLfile_close(void *file, H5VL_t *vol_plugin, hid_t req);
+H5_DLL void *H5VLfile_create(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VLfile_open(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLfile_flush(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5F_scope_t scope, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLfile_misc(void *file, H5VL_t *vol_plugin, H5VL_file_misc_t misc_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLfile_optional(void *file, H5VL_t *vol_plugin, H5VL_file_optional_t optional_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLfile_close(void *file, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
 
 /* GROUP OBJECT ROUTINES */
-H5_DLL void *H5VLgroup_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t req);
-H5_DLL void *H5VLgroup_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gapl_id, hid_t req);
-H5_DLL herr_t H5VLgroup_close(void *grp, H5VL_t *vol_plugin, hid_t req);
-H5_DLL herr_t H5VLgroup_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t req, va_list arguments);
+H5_DLL void *H5VLgroup_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VLgroup_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLgroup_close(void *grp, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLgroup_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
 
 /* LINK OBJECT ROUTINES */
-H5_DLL herr_t H5VLlink_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t req);
+H5_DLL herr_t H5VLlink_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
 H5_DLL herr_t H5VLlink_move(void *src_obj, H5VL_loc_params_t loc_params1,
                              void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin,
-                             hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t req);
+                             hbool_t copy_flag, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
 H5_DLL herr_t H5VLlink_iterate(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
                                 hbool_t recursive, H5_index_t idx_type, H5_iter_order_t order, 
-                                hsize_t *idx, H5L_iterate_t op, void *op_data, hid_t req);
-H5_DLL herr_t H5VLlink_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_get_t get_type, hid_t req, va_list arguments);
-H5_DLL herr_t H5VLlink_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t req);
+                                hsize_t *idx, H5L_iterate_t op, void *op_data, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLlink_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLlink_remove(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
 
 /* OBJECT ROUTINES */
-H5_DLL void *H5VLobject_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5I_type_t *opened_type, hid_t req);
+H5_DLL void *H5VLobject_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5I_type_t *opened_type, hid_t dxpl_id, void **req);
 H5_DLL herr_t H5VLobject_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugin1, const char *src_name, 
                                void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin2, const char *dst_name, 
-                               hid_t ocpypl_id, hid_t lcpl_id, hid_t req);
-H5_DLL herr_t H5VLobject_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5_index_t idx_type, H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t req);
-H5_DLL herr_t H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, hid_t req, va_list arguments);
-H5_DLL herr_t H5VLobject_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t misc_type, hid_t req, va_list arguments);
-H5_DLL herr_t H5VLobject_optional(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t optional_type, hid_t req, va_list arguments);
-H5_DLL herr_t H5VLobject_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t req);
+                               hid_t ocpypl_id, hid_t lcpl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLobject_visit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5_index_t idx_type, H5_iter_order_t order, H5O_iterate_t op, void *op_data, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLobject_misc(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t misc_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLobject_optional(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_misc_t optional_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLobject_close(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
+
+H5_DLL herr_t H5VLrequest_cancel(void **req, H5VL_t *vol_plugin, H5_status_t *status);
+H5_DLL herr_t H5VLrequest_test(void **req, H5VL_t *vol_plugin, H5_status_t *status);
+H5_DLL herr_t H5VLrequest_wait(void **req, H5VL_t *vol_plugin, H5_status_t *status);
 
 /* Function prototypes */
 H5_DLL hid_t H5VLregister(const H5VL_class_t *cls);