[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.

1 files changed, 232 insertions, 142 deletions

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() */