Merge pull request #1860 in HDFFV/hdf5 from ~DEROBINS/hdf5_der:map_api_merge to develop

* commit 'd95745235a468b17f697843adb3d0e54bd919893':
  Updated h5trav.c to emit output that doesn't require ddl changes for map support.
  Fixed Map API CMake option
  Renamed H5Mdelete_key to H5Mdelete and H5Mset to H5Mput.
  Added the map (H5M) API

35 files changed, 1900 insertions, 12 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 2b693bd..17fd949 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -393,6 +393,15 @@ set (H5L_HDRS
 IDE_GENERATED_PROPERTIES ("H5L" "${H5L_HDRS}" "${H5L_SOURCES}" )
 
 
+set (H5M_SOURCES
+    ${HDF5_SRC_DIR}/H5M.c
+)
+set (H5M_HDRS
+    ${HDF5_SRC_DIR}/H5Mpublic.h
+)
+IDE_GENERATED_PROPERTIES ("H5M" "${H5M_HDRS}" "${H5M_SOURCES}")
+
+
 set (H5MF_SOURCES
     ${HDF5_SRC_DIR}/H5MF.c
     ${HDF5_SRC_DIR}/H5MFaggr.c
@@ -483,6 +492,8 @@ set (H5P_SOURCES
     ${HDF5_SRC_DIR}/H5Pint.c
     ${HDF5_SRC_DIR}/H5Plapl.c
     ${HDF5_SRC_DIR}/H5Plcpl.c
+    ${HDF5_SRC_DIR}/H5Pmapl.c
+    ${HDF5_SRC_DIR}/H5Pmcpl.c
     ${HDF5_SRC_DIR}/H5Pocpl.c
     ${HDF5_SRC_DIR}/H5Pocpypl.c
     ${HDF5_SRC_DIR}/H5Pstrcpl.c
@@ -716,6 +727,7 @@ set (common_SRCS
     ${H5HP_SOURCES}
     ${H5I_SOURCES}
     ${H5L_SOURCES}
+    ${H5M_SOURCES}
     ${H5MF_SOURCES}
     ${H5MM_SOURCES}
     ${H5MP_SOURCES}
@@ -759,6 +771,7 @@ set (H5_PUBLIC_HEADERS
     ${H5HL_HDRS}
     ${H5I_HDRS}
     ${H5L_HDRS}
+    ${H5M_HDRS}
     ${H5MF_HDRS}
     ${H5MM_HDRS}
     ${H5MP_HDRS}
@@ -845,6 +858,9 @@ set (H5_PRIVATE_HEADERS
     ${HDF5_SRC_DIR}/H5Lpkg.h
     ${HDF5_SRC_DIR}/H5Lprivate.h
 
+    ${HDF5_SRC_DIR}/H5Mpkg.h
+    ${HDF5_SRC_DIR}/H5Mprivate.h
+
     ${HDF5_SRC_DIR}/H5MFprivate.h
 
     ${HDF5_SRC_DIR}/H5MMprivate.h
diff --git a/src/H5.c b/src/H5.c
index 104c9fd..16c12cb 100644
--- a/src/H5.c
+++ b/src/H5.c
@@ -166,6 +166,7 @@ H5_init_library(void)
     H5_debug_g.pkg[H5_PKG_HG].name = "hg";
     H5_debug_g.pkg[H5_PKG_HL].name = "hl";
     H5_debug_g.pkg[H5_PKG_I].name = "i";
+    H5_debug_g.pkg[H5_PKG_M].name = "m";
     H5_debug_g.pkg[H5_PKG_MF].name = "mf";
     H5_debug_g.pkg[H5_PKG_MM].name = "mm";
     H5_debug_g.pkg[H5_PKG_O].name = "o";
@@ -312,6 +313,7 @@ H5_term_library(void)
         pending += DOWN(A_top);
         pending += DOWN(D_top);
         pending += DOWN(G_top);
+        pending += DOWN(M_top);
         pending += DOWN(R_top);
         pending += DOWN(S_top);
         pending += DOWN(T_top);
@@ -337,6 +339,7 @@ H5_term_library(void)
             pending += DOWN(A);
             pending += DOWN(D);
             pending += DOWN(G);
+            pending += DOWN(M);
             pending += DOWN(R);
             pending += DOWN(S);
             pending += DOWN(T);
diff --git a/src/H5Fint.c b/src/H5Fint.c
index 7ed3ca8..c9c6658 100644
--- a/src/H5Fint.c
+++ b/src/H5Fint.c
@@ -498,6 +498,9 @@ H5F__get_objects_cb(void *obj_ptr, hid_t obj_id, void *key)
                     oloc = NULL;
                 break;
 
+            case H5I_MAP:
+                HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5_ITER_ERROR, "maps not supported in native VOL connector")
+
             case H5I_UNINIT:
             case H5I_BADID:
             case H5I_FILE:
@@ -3600,6 +3603,9 @@ H5F__get_file(void *obj, H5I_type_t type)
             oloc = H5A_oloc((H5A_t *)obj);
             break;
 
+        case H5I_MAP:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "maps not supported in native VOL connector")
+
         case H5I_UNINIT:
         case H5I_BADID:
         case H5I_DATASPACE:
diff --git a/src/H5Gdeprec.c b/src/H5Gdeprec.c
index 95627d2..5acb378 100644
--- a/src/H5Gdeprec.c
+++ b/src/H5Gdeprec.c
@@ -131,6 +131,9 @@ H5G_map_obj_type(H5O_type_t obj_type)
             ret_value = H5G_TYPE;
             break;
 
+        case H5O_TYPE_MAP:
+            /* Maps not supported in native VOL connector */
+
         case H5O_TYPE_UNKNOWN:
         case H5O_TYPE_NTYPES:
         default:
diff --git a/src/H5Gloc.c b/src/H5Gloc.c
index e47d3be..40d56c6 100644
--- a/src/H5Gloc.c
+++ b/src/H5Gloc.c
@@ -213,6 +213,9 @@ H5G_loc_real(void *obj, H5I_type_t type, H5G_loc_t *loc)
         case H5I_DATASPACE:
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to get group location of dataspace")
 
+        case H5I_MAP:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "maps not supported in native VOL connector")
+
         case H5I_GENPROP_CLS:
         case H5I_GENPROP_LST:
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to get group location of property list")
diff --git a/src/H5Gname.c b/src/H5Gname.c
index 16c1ca7..86a0c2f 100644
--- a/src/H5Gname.c
+++ b/src/H5Gname.c
@@ -816,6 +816,9 @@ H5G_name_replace_cb(void *obj_ptr, hid_t obj_id, void *key)
             obj_path = H5T_nameof((H5T_t *)obj_ptr);
             break;
 
+        case H5I_MAP:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "maps not supported in native VOL connector")
+
         case H5I_UNINIT:
         case H5I_BADID:
         case H5I_FILE:
@@ -1112,6 +1115,9 @@ H5G_name_replace(const H5O_link_t *lnk, H5G_names_op_t op, H5F_t *src_file,
                                 search_datatype = TRUE;
                                 break;
 
+                            case H5O_TYPE_MAP:
+                                HGOTO_ERROR(H5E_SYM, H5E_BADTYPE, FAIL, "maps not supported in native VOL connector")
+
                             case H5O_TYPE_UNKNOWN:
                             case H5O_TYPE_NTYPES:
                                 /* Search and replace names through datatype IDs */
diff --git a/src/H5Gtest.c b/src/H5Gtest.c
index 0b431b1..f9ab6f2 100644
--- a/src/H5Gtest.c
+++ b/src/H5Gtest.c
@@ -604,6 +604,9 @@ H5G__user_path_test(hid_t obj_id, char *user_path, size_t *user_path_len, unsign
             obj_path = H5T_nameof((H5T_t *)obj_ptr);
             break;
 
+        case H5I_MAP:
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "maps not supported in native VOL connector")
+
         case H5I_UNINIT:
         case H5I_BADID:
         case H5I_FILE:
diff --git a/src/H5I.c b/src/H5I.c
index 6b5210d..a2275de 100644
--- a/src/H5I.c
+++ b/src/H5I.c
@@ -2371,6 +2371,11 @@ H5I__id_dump_cb(void *_item, void H5_ATTR_UNUSED *_key, void *_udata)
             break;
         }
 
+        /* TODO: Maps will have to be added when they are supported in the
+         *       native VOL connector.
+         */
+        case H5I_MAP:
+
         case H5I_UNINIT:
         case H5I_BADID:
         case H5I_FILE:
diff --git a/src/H5Ipublic.h b/src/H5Ipublic.h
index def785f..34a408f 100644
--- a/src/H5Ipublic.h
+++ b/src/H5Ipublic.h
@@ -38,6 +38,7 @@ typedef enum H5I_type_t {
     H5I_DATATYPE,               /* type ID for Datatype objects                 */
     H5I_DATASPACE,              /* type ID for Dataspace objects                */
     H5I_DATASET,                /* type ID for Dataset objects                  */
+    H5I_MAP,                    /* type ID for Map objects                      */
     H5I_ATTR,                   /* type ID for Attribute objects                */
     H5I_VFL,                    /* type ID for virtual file layer               */
     H5I_VOL,                    /* type ID for virtual object layer             */
diff --git a/src/H5M.c b/src/H5M.c
new file mode 100644
index 0000000..adb4df0
--- /dev/null
+++ b/src/H5M.c
@@ -0,0 +1,1032 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/****************/
+/* Module Setup */
+/****************/
+
+#include "H5Mmodule.h"          /* This source code file is part of the H5M module */
+
+
+/***********/
+/* Headers */
+/***********/
+#include "H5private.h"          /* Generic Functions                        */
+#include "H5CXprivate.h"        /* API Contexts                             */
+#include "H5Mpkg.h"             /* Maps                                     */
+#include "H5Eprivate.h"         /* Error handling                           */
+#include "H5Iprivate.h"         /* IDs                                      */
+#include "H5VLprivate.h"        /* Virtual Object Layer                     */
+
+
+
+/****************/
+/* Local Macros */
+/****************/
+
+
+/******************/
+/* Local Typedefs */
+/******************/
+
+
+/********************/
+/* Local Prototypes */
+/********************/
+
+static herr_t H5M__close_cb(H5VL_object_t *map_vol_obj);
+
+
+/*********************/
+/* Package Variables */
+/*********************/
+
+/* Package initialization variable */
+hbool_t H5_PKG_INIT_VAR = FALSE;
+
+
+/*****************************/
+/* Library Private Variables */
+/*****************************/
+
+
+/*******************/
+/* Local Variables */
+/*******************/
+
+/* Map ID class */
+static const H5I_class_t H5I_MAP_CLS[1] = {{
+    H5I_MAP,                    /* ID class value */
+    0,                          /* Class flags */
+    0,                          /* # of reserved IDs for class */
+    (H5I_free_t)H5M__close_cb   /* Callback routine for closing objects of this class */
+}};
+
+/* Flag indicating "top" of interface has been initialized */
+static hbool_t H5M_top_package_initialize_s = FALSE;
+
+
+
+/*-------------------------------------------------------------------------
+NAME
+    H5M__init_package -- Initialize interface-specific information
+USAGE
+    herr_t H5M__init_package()
+
+RETURNS
+    Non-negative on success/Negative on failure
+DESCRIPTION
+    Initializes any interface-specific data or routines.
+---------------------------------------------------------------------------
+*/
+herr_t
+H5M__init_package(void)
+{
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    /* Initialize the atom group for the map IDs */
+    if(H5I_register_type(H5I_MAP_CLS) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTINIT, FAIL, "unable to initialize interface")
+
+    /* Mark "top" of interface as initialized, too */
+    H5M_top_package_initialize_s = TRUE;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5M__init_package() */
+
+
+/*-------------------------------------------------------------------------
+ * Function: H5M_top_term_package
+ *
+ * Purpose:  Close the "top" of the interface, releasing IDs, etc.
+ *
+ * Return:   Success:    Positive if anything was done that might
+ *                affect other interfaces; zero otherwise.
+ *           Failure:    Negative.
+ *-------------------------------------------------------------------------
+ */
+int
+H5M_top_term_package(void)
+{
+    int    n = 0;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    if(H5M_top_package_initialize_s) {
+        if(H5I_nmembers(H5I_MAP) > 0) {
+            (void)H5I_clear_type(H5I_MAP, FALSE, FALSE);
+            n++; /*H5I*/
+        } /* end if */
+
+        /* Mark closed */
+        if(0 == n)
+            H5M_top_package_initialize_s = FALSE;
+    } /* end if */
+
+    FUNC_LEAVE_NOAPI(n)
+} /* end H5M_top_term_package() */
+
+
+/*-------------------------------------------------------------------------
+ * Function: H5M_term_package
+ *
+ * Purpose:  Terminate this interface.
+ *
+ * Note:     Finishes shutting down the interface, after
+ *           H5M_top_term_package() is called
+ *
+ * Return:   Success:    Positive if anything was done that might
+ *                affect other interfaces; zero otherwise.
+ *            Failure:    Negative.
+ *-------------------------------------------------------------------------
+ */
+int
+H5M_term_package(void)
+{
+    int    n = 0;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    if(H5_PKG_INIT_VAR) {
+        /* Sanity checks */
+        HDassert(0 == H5I_nmembers(H5I_MAP));
+        HDassert(FALSE == H5M_top_package_initialize_s);
+
+        /* Destroy the dataset object id group */
+        n += (H5I_dec_type_ref(H5I_MAP) > 0);
+
+        /* Mark closed */
+        if(0 == n)
+            H5_PKG_INIT_VAR = FALSE;
+    } /* end if */
+
+    FUNC_LEAVE_NOAPI(n)
+} /* end H5M_term_package() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5M__close_cb
+ *
+ * Purpose:     Called when the ref count reaches zero on the map's ID
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5M__close_cb(H5VL_object_t *map_vol_obj)
+{
+    herr_t              ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Sanity check */
+    HDassert(map_vol_obj);
+
+    /* Close the map */
+    if(H5VL_optional(map_vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_MAP_CLOSE) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CLOSEERROR, FAIL, "unable to close map");
+
+    /* Free the VOL object */
+    if(H5VL_free_object(map_vol_obj) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTDEC, FAIL, "unable to free VOL object");
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5M__close_cb() */
+
+#ifdef H5_HAVE_MAP_API
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mcreate
+ *
+ * Purpose:     Creates a new map object for storing key-value pairs.  The
+ *              in-file datatype for keys is defined by KEY_TYPE_ID and
+ *              the in-file datatype for values is defined by VAL_TYPE_ID.
+ *              LOC_ID specifies the location to create the map object and
+ *              NAME specifies the name of the link to the object
+ *              (relative to LOC_ID).  Other options can be specified
+ *              through the property lists LCPL_ID, MCPL_ID, and MAPL_ID.
+ *
+ * Return:      Success:    The object ID of the new map.
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Mcreate(hid_t loc_id, const char *name, hid_t key_type_id, hid_t val_type_id,
+    hid_t lcpl_id, hid_t mcpl_id, hid_t mapl_id)
+{
+    void               *map = NULL;                         /* New map's info */
+    H5VL_object_t      *vol_obj = NULL;                     /* object token of loc_id */
+    H5VL_loc_params_t   loc_params;
+    hid_t               ret_value = H5I_INVALID_HID;        /* Return value */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE7("i", "i*siiiii", loc_id, name, key_type_id, val_type_id, lcpl_id,
+             mcpl_id, mapl_id);
+
+    /* Check arguments */
+    if(!name)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, H5I_INVALID_HID, "name parameter cannot be NULL")
+    if(!*name)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, H5I_INVALID_HID, "name parameter cannot be an empty string")
+
+    /* Get link creation property list */
+    if(H5P_DEFAULT == lcpl_id)
+        lcpl_id = H5P_LINK_CREATE_DEFAULT;
+    else
+        if(TRUE != H5P_isa_class(lcpl_id, H5P_LINK_CREATE))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "lcpl_id is not a link creation property list")
+
+    /* Get map creation property list */
+    if(H5P_DEFAULT == mcpl_id)
+        mcpl_id = H5P_MAP_CREATE_DEFAULT;
+    else
+        if(TRUE != H5P_isa_class(mcpl_id, H5P_MAP_CREATE))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "mcpl_id is not a map create property list ID")
+
+    /* Verify access property list and set up collective metadata if appropriate */
+    if(H5CX_set_apl(&mapl_id, H5P_CLS_MACC, loc_id, TRUE) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTSET, H5I_INVALID_HID, "can't set access property list info")
+
+    /* Get the location object */
+    if(NULL == (vol_obj = (H5VL_object_t *)H5I_object(loc_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
+
+    /* Set location parameters */
+    loc_params.type         = H5VL_OBJECT_BY_SELF;
+    loc_params.obj_type     = H5I_get_type(loc_id);
+
+    /* Create the map */
+    if(H5VL_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_MAP_CREATE, &loc_params, name, lcpl_id,
+            key_type_id, val_type_id, mcpl_id, mapl_id, &map) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTINIT, H5I_INVALID_HID, "unable to create map")
+
+    /* Get an atom for the map */
+    if((ret_value = H5VL_register(H5I_MAP, map, vol_obj->connector, TRUE)) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize map handle")
+
+done:
+    /* Cleanup on failure */
+    if(H5I_INVALID_HID == ret_value)
+        if(map && H5VL_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_MAP_CLOSE) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, H5I_INVALID_HID, "unable to release map")
+
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mcreate() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mcreate_anon
+ *
+ * Purpose:     Creates a new map object for storing key-value pairs.  The
+ *              in-file datatype for keys is defined by KEY_TYPE_ID and
+ *              the in-file datatype for values is defined by VAL_TYPE_ID.
+ *              LOC_ID specifies the file to create the map object, but no
+ *              link to the object is created.  Other options can be
+ *              specified through the property lists LCPL_ID, MCPL_ID, and
+ *              MAPL_ID.
+ *
+ *              The resulting ID should be linked into the file with
+ *              H5Olink or it will be deleted when closed.
+ *
+ * Return:      Success:    The object ID of the new map. The map should
+ *                          be linked into the group hierarchy before being closed or
+ *                          it will be deleted. The dataset should be
+ *                          closed when the caller is no longer interested
+ *                          in it.
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Mcreate_anon(hid_t loc_id, hid_t key_type_id, hid_t val_type_id,
+    hid_t mcpl_id, hid_t mapl_id)
+{
+    void                *map = NULL;                    /* map token from VOL connector */
+    H5VL_object_t       *vol_obj = NULL;                /* object token of loc_id */
+    H5VL_loc_params_t   loc_params;
+    hid_t               ret_value   = H5I_INVALID_HID;  /* Return value */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE5("i", "iiiii", loc_id, key_type_id, val_type_id, mcpl_id, mapl_id);
+
+    /* Check arguments */
+    if(H5P_DEFAULT == mcpl_id)
+        mcpl_id = H5P_MAP_CREATE_DEFAULT;
+    else
+        if(TRUE != H5P_isa_class(mcpl_id, H5P_MAP_CREATE))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "not map create property list ID")
+
+    /* Verify access property list and set up collective metadata if appropriate */
+    if(H5CX_set_apl(&mapl_id, H5P_CLS_MACC, loc_id, TRUE) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTSET, H5I_INVALID_HID, "can't set access property list info")
+
+    /* get the location object */
+    if(NULL == (vol_obj = (H5VL_object_t *)H5I_object(loc_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
+
+    /* Set location parameters */
+    loc_params.type     = H5VL_OBJECT_BY_SELF;
+    loc_params.obj_type = H5I_get_type(loc_id);
+
+    /* Create the map */
+    if(H5VL_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_MAP_CREATE, &loc_params, NULL, H5P_LINK_CREATE_DEFAULT,
+            key_type_id, val_type_id, mcpl_id, mapl_id, &map) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTINIT, H5I_INVALID_HID, "unable to create map")
+
+    /* Get an atom for the map */
+    if((ret_value = H5VL_register(H5I_MAP, map, vol_obj->connector, TRUE)) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register map")
+
+done:
+    /* Cleanup on failure */
+    if(H5I_INVALID_HID == ret_value)
+        if(map && H5VL_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_MAP_CLOSE) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, H5I_INVALID_HID, "unable to release map")
+
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mcreate_anon() */
+
+
+/*------------------------------------------------------------------------
+ * Function:    H5Mopen
+ *
+ * Purpose:     Finds a map named NAME at LOC_ID, opens it, and returns
+ *              its ID. The map should be close when the caller is no
+ *              longer interested in it.
+ *
+ *              Takes a map access property list
+ *
+ * Return:      Success:    Object ID of the map
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Mopen(hid_t loc_id, const char *name, hid_t mapl_id)
+{
+    void               *map = NULL;             /* map token from VOL connector */
+    H5VL_object_t      *vol_obj = NULL;         /* object token of loc_id */
+    H5VL_loc_params_t   loc_params;
+    hid_t               ret_value   = H5I_INVALID_HID;  /* Return value */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE3("i", "i*si", loc_id, name, mapl_id);
+
+    /* Check args */
+    if(!name)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, H5I_INVALID_HID, "name parameter cannot be NULL")
+    if(!*name)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, H5I_INVALID_HID, "name parameter cannot be an empty string")
+
+    /* Verify access property list and set up collective metadata if appropriate */
+    if(H5CX_set_apl(&mapl_id, H5P_CLS_MACC, loc_id, FALSE) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTSET, H5I_INVALID_HID, "can't set access property list info")
+
+    /* get the location object */
+    if(NULL == (vol_obj = (H5VL_object_t *)H5I_object(loc_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
+
+    /* Set the location parameters */
+    loc_params.type         = H5VL_OBJECT_BY_SELF;
+    loc_params.obj_type     = H5I_get_type(loc_id);
+
+    /* Open the map */
+    if(H5VL_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_MAP_OPEN, &loc_params, name, mapl_id, &map) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open map")
+
+    /* Register an atom for the map */
+    if((ret_value = H5VL_register(H5I_MAP, map, vol_obj->connector, TRUE)) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTREGISTER, H5I_INVALID_HID, "can't register map atom")
+
+done:
+    /* Cleanup on failure */
+    if(H5I_INVALID_HID == ret_value)
+        if(map && H5VL_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_MAP_CLOSE) < 0)
+            HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, H5I_INVALID_HID, "unable to release map")
+
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mopen() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mclose
+ *
+ * Purpose:     Closes access to a map and releases resources used by it.
+ *              It is illegal to subsequently use that same map ID in
+ *              calls to other map functions.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Mclose(hid_t map_id)
+{
+    herr_t  ret_value = SUCCEED;    /* Return value                     */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE1("e", "i", map_id);
+
+    /* Check args */
+    if(H5I_MAP != H5I_get_type(map_id))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a map ID")
+
+    /* Decrement the counter on the map.  It will be freed if the count
+     * reaches zero.  
+     */
+    if(H5I_dec_app_ref_always_close(map_id) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTDEC, FAIL, "can't decrement count on map ID")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mclose() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mget_key_type
+ *
+ * Purpose:     Returns a copy of the key datatype for a map.
+ *
+ * Return:      Success:    ID for a copy of the datatype. The data
+ *                          type should be released by calling
+ *                          H5Tclose().
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Mget_key_type(hid_t map_id)
+{
+    H5VL_object_t  *vol_obj;                        /* Map structure    */
+    hid_t           ret_value = H5I_INVALID_HID;    /* Return value         */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE1("i", "i", map_id);
+
+    /* Check args */
+    if(NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(map_id, H5I_MAP)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid map identifier")
+
+    /* get the datatype */
+    if(H5VL_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_MAP_GET, H5VL_MAP_GET_KEY_TYPE, &ret_value) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTGET, H5I_INVALID_HID, "unable to get datatype")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mget_key_type() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mget_val_type
+ *
+ * Purpose:     Returns a copy of the value datatype for a map.
+ *
+ * Return:      Success:    ID for a copy of the datatype. The data
+ *                          type should be released by calling
+ *                          H5Tclose().
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Mget_val_type(hid_t map_id)
+{
+    H5VL_object_t  *vol_obj;                        /* Map structure    */
+    hid_t           ret_value = H5I_INVALID_HID;    /* Return value         */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE1("i", "i", map_id);
+
+    /* Check args */
+    if(NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(map_id, H5I_MAP)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid map identifier")
+
+    /* get the datatype */
+    if(H5VL_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_MAP_GET, H5VL_MAP_GET_VAL_TYPE, &ret_value) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTGET, H5I_INVALID_HID, "unable to get datatype")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mget_val_type() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mget_create_plist
+ *
+ * Purpose:     Returns a copy of the map creation property list.
+ *
+ * Return:      Success:    ID for a copy of the map creation
+ *                          property list.  The template should be
+ *                          released by calling H5P_close().
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Mget_create_plist(hid_t map_id)
+{
+    H5VL_object_t  *vol_obj;                        /* Map structure    */
+    hid_t           ret_value = H5I_INVALID_HID;    /* Return value         */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE1("i", "i", map_id);
+
+    /* Check args */
+    if(NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(map_id, H5I_MAP)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid map identifier")
+
+    /* Get the map creation property list */
+    if(H5VL_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_MAP_GET, H5VL_MAP_GET_MCPL, &ret_value) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTGET, H5I_INVALID_HID, "unable to get map creation properties")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mget_create_plist() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mget_access_plist
+ *
+ * Purpose:     Returns a copy of the map access property list.
+ *
+ * Description: H5Mget_access_plist returns the map access property
+ *              list identifier of the specified map.
+ *
+ * Return:      Success:    ID for a copy of the map access
+ *                          property list.  The template should be
+ *                          released by calling H5Pclose().
+ *
+ *              Failure:    H5I_INVALID_HID
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5Mget_access_plist(hid_t map_id)
+{
+    H5VL_object_t  *vol_obj;                        /* Map structure    */
+    hid_t           ret_value = H5I_INVALID_HID;    /* Return value         */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE1("i", "i", map_id);
+
+    /* Check args */
+    if(NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(map_id, H5I_MAP)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid map identifier")
+
+    /* Get the map access property list */
+    if(H5VL_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_MAP_GET, H5VL_MAP_GET_MAPL, &ret_value) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTGET, H5I_INVALID_HID, "unable to get map access properties")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mget_access_plist() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mget_count
+ *
+ * Purpose:     Returns the number of key-value pairs stored in the map.
+ *
+ * Description: H5Mget_count returns the number of key-value pairs stored
+ *              in the specified map.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Mget_count(hid_t map_id, hsize_t *count, hid_t dxpl_id)
+{
+    H5VL_object_t  *vol_obj;                        /* Map structure    */
+    herr_t          ret_value = SUCCEED;            /* Return value         */
+
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE3("e", "i*hi", map_id, count, dxpl_id);
+
+    /* Check args */
+    if(NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(map_id, H5I_MAP)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid map identifier")
+
+    /* Get the default dataset transfer property list if the user didn't provide one */
+    if (H5P_DEFAULT == dxpl_id)
+        dxpl_id = H5P_DATASET_XFER_DEFAULT;
+    else
+        if (TRUE != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms")
+
+    /* Set DXPL for operation */
+    H5CX_set_dxpl(dxpl_id);
+
+    /* Get the number of key-value pairs stored in the map */
+    if(H5VL_optional(vol_obj, dxpl_id, H5_REQUEST_NULL, H5VL_MAP_GET, H5VL_MAP_GET_COUNT, count) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTGET, H5I_INVALID_HID, "unable to get map access properties")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mget_count() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mput
+ *
+ * Purpose:     H5Mput adds a key-value pair to the Map specified by
+ *              MAP_ID, or updates the value for the specified key if one
+ *              was set previously. KEY_MEM_TYPE_ID and VAL_MEM_TYPE_ID
+ *              specify the datatypes for the provided KEY and VALUE
+ *              buffers, and if different from those used to create the
+ *              map object, the key and value will be internally converted
+ *              to the datatypes for the map object. Any further options
+ *              can be specified through the property list DXPL_ID.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Mput(hid_t map_id, hid_t key_mem_type_id, const void *key,
+    hid_t val_mem_type_id, const void *value, hid_t dxpl_id)
+{
+    H5VL_object_t          *vol_obj = NULL;
+    herr_t                  ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE6("e", "ii*xi*xi", map_id, key_mem_type_id, key, val_mem_type_id, value,
+             dxpl_id);
+
+    /* Check arguments */
+    if (key_mem_type_id < 0)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid key memory datatype ID")
+    if (val_mem_type_id < 0)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid value memory datatype ID")
+
+    /* Get map pointer */
+    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(map_id, H5I_MAP)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "map_id is not a map ID")
+
+    /* Get the default dataset transfer property list if the user didn't provide one */
+    if (H5P_DEFAULT == dxpl_id)
+        dxpl_id = H5P_DATASET_XFER_DEFAULT;
+    else
+        if (TRUE != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms")
+
+    /* Set DXPL for operation */
+    H5CX_set_dxpl(dxpl_id);
+
+    /* Set the key/value pair */
+    if(H5VL_optional(vol_obj, dxpl_id, H5_REQUEST_NULL, H5VL_MAP_PUT, key_mem_type_id, key, val_mem_type_id, value) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTSET, FAIL, "unable to put key/value pair")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mput() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mget
+ *
+ * Purpose:     H5Mget retrieves, from the Map specified by MAP_ID, the
+ *              value associated with the provided key.  KEY_MEM_TYPE_ID
+ *              and VAL_MEM_TYPE_ID specify the datatypes for the provided
+ *              KEY and VALUE buffers. If KEY_MEM_TYPE_ID is different
+ *              from that used to create the map object, the key will be
+ *              internally converted to the datatype for the map object
+ *              for the query, and if VAL_MEM_TYPE_ID is different from
+ *              that used to create the map object, the returned value
+ *              will be converted to VAL_MEM_TYPE_ID before the function
+ *              returns. Any further options can be specified through the
+ *              property list DXPL_ID.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Mget(hid_t map_id, hid_t key_mem_type_id, const void *key,
+    hid_t val_mem_type_id, void *value, hid_t dxpl_id)
+{
+    H5VL_object_t          *vol_obj = NULL;
+    herr_t                  ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE6("e", "ii*xi*xi", map_id, key_mem_type_id, key, val_mem_type_id, value,
+             dxpl_id);
+
+    /* Check arguments */
+    if (key_mem_type_id < 0)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid key memory datatype ID")
+    if (val_mem_type_id < 0)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid value memory datatype ID")
+
+    /* Get map pointer */
+    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(map_id, H5I_MAP)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "map_id is not a map ID")
+
+    /* Get the default dataset transfer property list if the user didn't provide one */
+    if (H5P_DEFAULT == dxpl_id)
+        dxpl_id = H5P_DATASET_XFER_DEFAULT;
+    else
+        if (TRUE != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms")
+
+    /* Set DXPL for operation */
+    H5CX_set_dxpl(dxpl_id);
+
+    /* Get the value for the key */
+    if(H5VL_optional(vol_obj, dxpl_id, H5_REQUEST_NULL, H5VL_MAP_GET_VAL, key_mem_type_id, key, val_mem_type_id, value) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTGET, FAIL, "unable to get value from map")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mget() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mexists
+ *
+ * Purpose:     H5Mexists checks if the provided key is stored in the map
+ *              specified by MAP_ID. If KEY_MEM_TYPE_ID is different from
+ *              that used to create the map object the key will be
+ *              internally converted to the datatype for the map object
+ *              for the query.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Mexists(hid_t map_id, hid_t key_mem_type_id, const void *key, hbool_t *exists,
+    hid_t dxpl_id)
+{
+    H5VL_object_t          *vol_obj = NULL;
+    herr_t                  ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE5("e", "ii*x*bi", map_id, key_mem_type_id, key, exists, dxpl_id);
+
+    /* Check arguments */
+    if (key_mem_type_id < 0)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid key memory datatype ID")
+
+    /* Get map pointer */
+    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(map_id, H5I_MAP)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "map_id is not a map ID")
+
+    /* Get the default dataset transfer property list if the user didn't provide one */
+    if (H5P_DEFAULT == dxpl_id)
+        dxpl_id = H5P_DATASET_XFER_DEFAULT;
+    else
+        if (TRUE != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms")
+
+    /* Set DXPL for operation */
+    H5CX_set_dxpl(dxpl_id);
+
+    /* Check if key exists */
+    if((ret_value = H5VL_optional(vol_obj, dxpl_id, H5_REQUEST_NULL, H5VL_MAP_EXISTS, key_mem_type_id, key, exists)) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTGET, ret_value, "unable to check if key exists")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mexists() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Miterate
+ *
+ * Purpose:     H5Miterate iterates over all key-value pairs stored in the
+ *              map specified by MAP_ID, making the callback specified by
+ *              OP for each. The IDX parameter is an in/out parameter that
+ *              may be used to restart a previously interrupted iteration.
+ *              At the start of iteration IDX should be set to 0, and to
+ *              restart iteration at the same location on a subsequent
+ *              call to H5Miterate, IDX should be the same value as
+ *              returned by the previous call.
+ * 
+ *              H5M_iterate_t is defined as:
+ *              herr_t (*H5M_iterate_t)(hid_t map_id, const void *key,
+ *                      void *ctx)
+ *
+ *              The KEY parameter is the buffer for the key for this
+ *              iteration, converted to the datatype specified by
+ *              KEY_MEM_TYPE_ID. The OP_DATA parameter is a simple pass
+ *              through of the value passed to H5Miterate, which can be
+ *              used to store application-defined data for iteration. A
+ *              negative return value from this function will cause
+ *              H5Miterate to issue an error, while a positive return
+ *              value will cause H5Miterate to stop iterating and return
+ *              this value without issuing an error. A return value of
+ *              zero allows iteration to continue.
+ *
+ * Return:      Last value returned by op
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Miterate(hid_t map_id, hsize_t *idx, hid_t key_mem_type_id, H5M_iterate_t op,
+    void *op_data, hid_t dxpl_id)
+{
+    H5VL_object_t          *vol_obj = NULL;
+    H5VL_loc_params_t       loc_params;
+    herr_t                  ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE6("e", "i*hix*xi", map_id, idx, key_mem_type_id, op, op_data, dxpl_id);
+
+    /* Check arguments */
+    if (key_mem_type_id < 0)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid key memory datatype ID")
+    if (!op)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no operator specified")
+
+    /* Get map pointer */
+    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(map_id, H5I_MAP)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "map_id is not a map ID")
+
+    /* Get the default dataset transfer property list if the user didn't provide one */
+    if (H5P_DEFAULT == dxpl_id)
+        dxpl_id = H5P_DATASET_XFER_DEFAULT;
+    else
+        if (TRUE != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms")
+
+    /* Set DXPL for operation */
+    H5CX_set_dxpl(dxpl_id);
+
+    /* Set location struct fields */
+    loc_params.type = H5VL_OBJECT_BY_SELF;
+    loc_params.obj_type = H5I_get_type(map_id);
+
+    /* Iterate over keys */
+    if((ret_value = H5VL_optional(vol_obj, dxpl_id, H5_REQUEST_NULL, H5VL_MAP_SPECIFIC, &loc_params, H5VL_MAP_ITER, idx, key_mem_type_id, op, op_data)) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_BADITER, ret_value, "unable to ierate over keys")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Miterate() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Miterate_by_name
+ *
+ * Purpose:     H5Miterate_by_name iterates over all key-value pairs
+ *              stored in the map specified by MAP_ID, making the callback
+ *              specified by OP for each. The IDX parameter is an in/out
+ *              parameter that may be used to restart a previously
+ *              interrupted iteration.  At the start of iteration IDX
+ *              should be set to 0, and to restart iteration at the same
+ *              location on a subsequent call to H5Miterate, IDX should be
+ *              the same value as returned by the previous call.
+ *
+ *              H5M_iterate_t is defined as:
+ *              herr_t (*H5M_iterate_t)(hid_t map_id, const void *key,
+ *                      void *ctx)
+ *
+ *              The KEY parameter is the buffer for the key for this
+ *              iteration, converted to the datatype specified by
+ *              KEY_MEM_TYPE_ID. The OP_DATA parameter is a simple pass
+ *              through of the value passed to H5Miterate, which can be
+ *              used to store application-defined data for iteration. A
+ *              negative return value from this function will cause
+ *              H5Miterate to issue an error, while a positive return
+ *              value will cause H5Miterate to stop iterating and return
+ *              this value without issuing an error. A return value of
+ *              zero allows iteration to continue.
+ *
+ * Return:      Last value returned by op
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Miterate_by_name(hid_t loc_id, const char *map_name, hsize_t *idx,
+    hid_t key_mem_type_id, H5M_iterate_t op, void *op_data, hid_t dxpl_id,
+    hid_t lapl_id)
+{
+    H5VL_object_t          *vol_obj = NULL;
+    H5VL_loc_params_t       loc_params;
+    herr_t                  ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE8("e", "i*s*hix*xii", loc_id, map_name, idx, key_mem_type_id, op,
+             op_data, dxpl_id, lapl_id);
+
+    /* Check arguments */
+    if(!map_name)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "map_name parameter cannot be NULL")
+    if(!*map_name)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "map_name parameter cannot be an empty string")
+    if (key_mem_type_id < 0)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid key memory datatype ID")
+    if (!op)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no operator specified")
+
+    /* Get the location object */
+    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object(loc_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
+
+    /* Get the default dataset transfer property list if the user didn't provide one */
+    if (H5P_DEFAULT == dxpl_id)
+        dxpl_id = H5P_DATASET_XFER_DEFAULT;
+    else
+        if (TRUE != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms")
+
+    /* Set DXPL for operation */
+    H5CX_set_dxpl(dxpl_id);
+
+    /* Set location struct fields */
+    loc_params.type                         = H5VL_OBJECT_BY_NAME;
+    loc_params.obj_type                     = H5I_get_type(loc_id);
+    loc_params.loc_data.loc_by_name.name    = map_name;
+    loc_params.loc_data.loc_by_name.lapl_id = lapl_id;
+
+    /* Iterate over keys */
+    if((ret_value = H5VL_optional(vol_obj, dxpl_id, H5_REQUEST_NULL, H5VL_MAP_SPECIFIC, &loc_params, H5VL_MAP_ITER, idx, key_mem_type_id, op, op_data)) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_BADITER, ret_value, "unable to ierate over keys")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Miterate_by_name() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Mdelete
+ *
+ * Purpose:     H5Mdelete deletes a key-value pair from the Map
+ *              specified by MAP_ID. KEY_MEM_TYPE_ID specifies the
+ *              datatype for the provided key buffers, and if different
+ *              from that used to create the Map object, the key will be
+ *              internally converted to the datatype for the map object.
+ *              Any further options can be specified through the property
+ *              list DXPL_ID.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Mdelete(hid_t map_id, hid_t key_mem_type_id, const void *key,
+    hid_t dxpl_id)
+{
+    H5VL_object_t          *vol_obj = NULL;
+    H5VL_loc_params_t       loc_params;
+    herr_t                  ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE4("e", "ii*xi", map_id, key_mem_type_id, key, dxpl_id);
+
+    /* Check arguments */
+    if (key_mem_type_id < 0)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid key memory datatype ID")
+
+    /* Get map pointer */
+    if (NULL == (vol_obj = (H5VL_object_t *)H5I_object_verify(map_id, H5I_MAP)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "map_id is not a map ID")
+
+    /* Get the default dataset transfer property list if the user didn't provide one */
+    if (H5P_DEFAULT == dxpl_id)
+        dxpl_id = H5P_DATASET_XFER_DEFAULT;
+    else
+        if (TRUE != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms")
+
+    /* Set DXPL for operation */
+    H5CX_set_dxpl(dxpl_id);
+
+    /* Set location struct fields */
+    loc_params.type = H5VL_OBJECT_BY_SELF;
+    loc_params.obj_type = H5I_get_type(map_id);
+
+    /* Delete the key/value pair */
+    if(H5VL_optional(vol_obj, dxpl_id, H5_REQUEST_NULL, H5VL_MAP_SPECIFIC, &loc_params, H5VL_MAP_DELETE, key_mem_type_id, key) < 0)
+        HGOTO_ERROR(H5E_MAP, H5E_CANTSET, FAIL, "unable to delete key/value pair")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Mdelete() */
+
+#endif /*  H5_HAVE_MAP_API */
+
diff --git a/src/H5Mmodule.h b/src/H5Mmodule.h
new file mode 100644
index 0000000..00a586f
--- /dev/null
+++ b/src/H5Mmodule.h
@@ -0,0 +1,31 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * Purpose:     This file contains declarations which define macros for the
+ *              H5M package.  Including this header means that the source file
+ *              is part of the H5M package.
+ */
+#ifndef _H5Mmodule_H
+#define _H5Mmodule_H
+
+/* Define the proper control macros for the generic FUNC_ENTER/LEAVE and error
+ *      reporting macros.
+ */
+#define H5M_MODULE
+#define H5_MY_PKG       H5M
+#define H5_MY_PKG_ERR   H5E_MAP
+#define H5_MY_PKG_INIT  YES
+
+#endif /* _H5Dmodule_H */
+
+
diff --git a/src/H5Mpkg.h b/src/H5Mpkg.h
new file mode 100644
index 0000000..86ff45c
--- /dev/null
+++ b/src/H5Mpkg.h
@@ -0,0 +1,51 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * Purpose:    This file contains declarations which are visible only within
+ *        the H5M package.  Source files outside the H5M package should
+ *        include H5Mprivate.h instead.
+ */
+#if !(defined H5M_FRIEND || defined H5M_MODULE)
+#error "Do not include this file outside the H5M package!"
+#endif
+
+#ifndef _H5Mpkg_H
+#define _H5Mpkg_H
+
+/* Get package's private header */
+#include "H5Mprivate.h"
+
+/* Other private headers needed by this file */
+
+/**************************/
+/* Package Private Macros */
+/**************************/
+
+
+/****************************/
+/* Package Private Typedefs */
+/****************************/
+
+
+/*****************************/
+/* Package Private Variables */
+/*****************************/
+
+
+/******************************/
+/* Package Private Prototypes */
+/******************************/
+
+#endif /*_H5Dpkg_H*/
+
diff --git a/src/H5Mprivate.h b/src/H5Mprivate.h
new file mode 100644
index 0000000..c841e75
--- /dev/null
+++ b/src/H5Mprivate.h
@@ -0,0 +1,80 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * This file contains private information about the H5M module
+ */
+#ifndef _H5Mprivate_H
+#define _H5Mprivate_H
+
+/* Include package's public header */
+#include "H5Mpublic.h"
+
+/* Private headers needed by this file */
+#include "H5FDprivate.h"       /* File drivers                */
+#include "H5Oprivate.h"        /* Object headers              */
+#include "H5Sprivate.h"        /* Dataspaces                  */
+#include "H5Zprivate.h"        /* Data filters                */
+
+
+/**************************/
+/* Library Private Macros */
+/**************************/
+
+/*
+ * Feature: Define H5M_DEBUG on the compiler command line if you want to
+ *        debug maps. NDEBUG must not be defined in order for this
+ *        to have any effect.
+ */
+#ifdef NDEBUG
+#  undef H5M_DEBUG
+#endif
+
+/* ========  Map creation property names ======== */
+
+/* ========  Map access property names ======== */
+#define H5M_ACS_KEY_PREFETCH_SIZE_NAME      "key_prefetch_size" /* Number of keys to prefetch during map iteration */
+#define H5M_ACS_KEY_ALLOC_SIZE_NAME         "key_alloc_size" /* Initial allocation size for keys prefetched during map iteration */
+
+/* Default temporary buffer size */
+#define H5D_TEMP_BUF_SIZE       (1024 * 1024)
+
+/* Default I/O vector size */
+#define H5D_IO_VECTOR_SIZE      1024
+
+/* Default VL allocation & free info */
+#define H5D_VLEN_ALLOC          NULL
+#define H5D_VLEN_ALLOC_INFO     NULL
+#define H5D_VLEN_FREE           NULL
+#define H5D_VLEN_FREE_INFO      NULL
+
+/* Default virtual dataset list size */
+#define H5D_VIRTUAL_DEF_LIST_SIZE 8
+
+
+/****************************/
+/* Library Private Typedefs */
+/****************************/
+
+
+/*****************************/
+/* Library Private Variables */
+/*****************************/
+
+
+/******************************/
+/* Library Private Prototypes */
+/******************************/
+
+#endif /* _H5Mprivate_H */
+
diff --git a/src/H5Mpublic.h b/src/H5Mpublic.h
new file mode 100644
index 0000000..9cbdb32
--- /dev/null
+++ b/src/H5Mpublic.h
@@ -0,0 +1,126 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * This file contains public declarations for the H5M module.
+ *
+ * NOTE:    This is an experimental API. Everything in the H5M package
+ *          is subject to revision in a future release.
+ */
+#ifndef _H5Mpublic_H
+#define _H5Mpublic_H
+
+/* System headers needed by this file */
+
+/* Public headers needed by this file */
+#include "H5public.h"
+#include "H5Ipublic.h"
+
+
+/*****************/
+/* Public Macros */
+/*****************/
+
+/* Macros defining operation IDs for map VOL callbacks (implemented using the
+ * "optional" VOL callback) */
+#define H5VL_MAP_CREATE         1
+#define H5VL_MAP_OPEN           2
+#define H5VL_MAP_GET_VAL        3
+#define H5VL_MAP_EXISTS         4
+#define H5VL_MAP_PUT            5
+#define H5VL_MAP_GET            6
+#define H5VL_MAP_SPECIFIC       7
+#define H5VL_MAP_CLOSE          8
+
+
+/*******************/
+/* Public Typedefs */
+/*******************/
+
+/* types for map GET callback */
+typedef enum H5VL_map_get_t {
+    H5VL_MAP_GET_MAPL,                      /* map access property list */
+    H5VL_MAP_GET_MCPL,                      /* map creation property list */
+    H5VL_MAP_GET_KEY_TYPE,                  /* key type                 */
+    H5VL_MAP_GET_VAL_TYPE,                  /* value type               */
+    H5VL_MAP_GET_COUNT                      /* key count                */
+} H5VL_map_get_t;
+
+/* types for map SPECIFIC callback */
+typedef enum H5VL_map_specific_t {
+    H5VL_MAP_ITER,                          /* H5Miterate               */
+    H5VL_MAP_DELETE                         /* H5Mdelete                */
+} H5VL_map_specific_t;
+
+/* Callback for H5Miterate() */
+typedef herr_t (*H5M_iterate_t)(hid_t map_id, const void *key, void *op_data);
+
+
+/********************/
+/* Public Variables */
+/********************/
+
+
+/*********************/
+/* Public Prototypes */
+/*********************/
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* The map API is only built when requested since there's no support in
+ * the native file format at this time. It's only supported in a few VOL
+ * connectors.
+ */
+#ifdef H5_HAVE_MAP_API
+
+H5_DLL hid_t H5Mcreate(hid_t loc_id, const char *name, hid_t key_type_id,
+    hid_t val_type_id, hid_t lcpl_id, hid_t mcpl_id, hid_t mapl_id);
+H5_DLL hid_t H5Mcreate_anon(hid_t loc_id, hid_t key_type_id, hid_t val_type_id,
+    hid_t mcpl_id, hid_t mapl_id);
+H5_DLL hid_t H5Mopen(hid_t loc_id, const char *name, hid_t mapl_id);
+H5_DLL herr_t H5Mclose(hid_t map_id);
+H5_DLL hid_t H5Mget_key_type(hid_t map_id);
+H5_DLL hid_t H5Mget_val_type(hid_t map_id);
+H5_DLL hid_t H5Mget_create_plist(hid_t map_id);
+H5_DLL hid_t H5Mget_access_plist(hid_t map_id);
+H5_DLL herr_t H5Mget_count(hid_t map_id, hsize_t *count, hid_t dxpl_id);
+H5_DLL herr_t H5Mput(hid_t map_id, hid_t key_mem_type_id, const void *key,
+    hid_t val_mem_type_id, const void *value, hid_t dxpl_id);
+H5_DLL herr_t H5Mget(hid_t map_id, hid_t key_mem_type_id, const void *key,
+    hid_t val_mem_type_id, void *value, hid_t dxpl_id);
+H5_DLL herr_t H5Mexists(hid_t map_id, hid_t key_mem_type_id, const void *key,
+    hbool_t *exists, hid_t dxpl_id);
+H5_DLL herr_t H5Miterate(hid_t map_id, hsize_t *idx, hid_t key_mem_type_id,
+    H5M_iterate_t op, void *op_data, hid_t dxpl_id);
+H5_DLL herr_t H5Miterate_by_name(hid_t loc_id, const char *map_name,
+    hsize_t *idx, hid_t key_mem_type_id, H5M_iterate_t op, void *op_data,
+    hid_t dxpl_id, hid_t lapl_id);
+H5_DLL herr_t H5Mdelete(hid_t map_id, hid_t key_mem_type_id,
+    const void *key, hid_t dxpl_id);
+
+/* Symbols defined for compatibility with previous versions of the HDF5 API.
+ *
+ * Use of these symbols is deprecated.
+ */
+#ifndef H5_NO_DEPRECATED_SYMBOLS
+#endif /* H5_NO_DEPRECATED_SYMBOLS */
+
+#endif /*  H5_HAVE_MAP_API */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _H5Mpublic_H */
+
diff --git a/src/H5O.c b/src/H5O.c
index 093d429..e7351fc 100644
--- a/src/H5O.c
+++ b/src/H5O.c
@@ -1084,6 +1084,7 @@ H5Oclose(hid_t object_id)
         case H5I_GROUP:
         case H5I_DATATYPE:
         case H5I_DATASET:
+        case H5I_MAP:
             if(H5I_object(object_id) == NULL)
                 HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "not a valid object")
             if(H5I_dec_app_ref(object_id) < 0)
diff --git a/src/H5Oflush.c b/src/H5Oflush.c
index f5ede4a..a03cfa1 100644
--- a/src/H5Oflush.c
+++ b/src/H5Oflush.c
@@ -479,6 +479,9 @@ H5O_refresh_metadata_reopen(hid_t oid, H5G_loc_t *obj_loc, H5VL_t *vol_connector
                     HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, FAIL, "unable to finish refresh for dataset")
             break;
 
+        case H5I_MAP:
+            HGOTO_ERROR(H5E_OHDR, H5E_BADTYPE, FAIL, "maps not supported in native VOL connector")
+
         case H5I_UNINIT:
         case H5I_BADID:
         case H5I_FILE:
diff --git a/src/H5Oint.c b/src/H5Oint.c
index 45a8046..e37eea5 100644
--- a/src/H5Oint.c
+++ b/src/H5Oint.c
@@ -1836,6 +1836,9 @@ H5O_get_loc(hid_t object_id)
                 HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, NULL, "unable to get object location from datatype ID")
             break;
 
+        case H5I_MAP:
+            HGOTO_ERROR(H5E_OHDR, H5E_BADTYPE, NULL, "maps not supported in native VOL connector")
+
         case H5I_UNINIT:
         case H5I_BADID:
         case H5I_FILE:
diff --git a/src/H5Opublic.h b/src/H5Opublic.h
index c868e72..234f4f0 100644
--- a/src/H5Opublic.h
+++ b/src/H5Opublic.h
@@ -94,6 +94,7 @@ typedef enum H5O_type_t {
     H5O_TYPE_GROUP,	        /* Object is a group		*/
     H5O_TYPE_DATASET,		/* Object is a dataset		*/
     H5O_TYPE_NAMED_DATATYPE, 	/* Object is a named data type	*/
+    H5O_TYPE_MAP,               /* Object is a map */
     H5O_TYPE_NTYPES             /* Number of different object types (must be last!) */
 } H5O_type_t;
 
diff --git a/src/H5Pencdec.c b/src/H5Pencdec.c
index 8b9962f..2a07a67 100644
--- a/src/H5Pencdec.c
+++ b/src/H5Pencdec.c
@@ -722,7 +722,7 @@ H5P__decode(const void *buf)
 
     /* Get the type of the property list */
     type = (H5P_plist_type_t)*p++;
-    if(type <= H5P_TYPE_USER || type > H5P_TYPE_LINK_ACCESS)
+    if(type <= H5P_TYPE_USER || type >= H5P_TYPE_MAX_TYPE)
         HGOTO_ERROR(H5E_PLIST, H5E_BADRANGE, FAIL, "bad type of encoded information: %u", (unsigned)type)
 
     /* Create new property list of the specified type */
diff --git a/src/H5Pint.c b/src/H5Pint.c
index 5683403..36367d7 100644
--- a/src/H5Pint.c
+++ b/src/H5Pint.c
@@ -151,6 +151,10 @@ hid_t H5P_CLS_DATATYPE_CREATE_ID_g              = H5I_INVALID_HID;
 H5P_genclass_t *H5P_CLS_DATATYPE_CREATE_g       = NULL;
 hid_t H5P_CLS_DATATYPE_ACCESS_ID_g              = H5I_INVALID_HID;
 H5P_genclass_t *H5P_CLS_DATATYPE_ACCESS_g       = NULL;
+hid_t H5P_CLS_MAP_CREATE_ID_g                   = H5I_INVALID_HID;
+H5P_genclass_t *H5P_CLS_MAP_CREATE_g            = NULL;
+hid_t H5P_CLS_MAP_ACCESS_ID_g                   = H5I_INVALID_HID;
+H5P_genclass_t *H5P_CLS_MAP_ACCESS_g            = NULL;
 hid_t H5P_CLS_ATTRIBUTE_CREATE_ID_g             = H5I_INVALID_HID;
 H5P_genclass_t *H5P_CLS_ATTRIBUTE_CREATE_g      = NULL;
 hid_t H5P_CLS_ATTRIBUTE_ACCESS_ID_g             = H5I_INVALID_HID;
@@ -180,6 +184,8 @@ hid_t H5P_LST_GROUP_CREATE_ID_g         = H5I_INVALID_HID;
 hid_t H5P_LST_GROUP_ACCESS_ID_g         = H5I_INVALID_HID;
 hid_t H5P_LST_DATATYPE_CREATE_ID_g      = H5I_INVALID_HID;
 hid_t H5P_LST_DATATYPE_ACCESS_ID_g      = H5I_INVALID_HID;
+hid_t H5P_LST_MAP_CREATE_ID_g           = H5I_INVALID_HID;
+hid_t H5P_LST_MAP_ACCESS_ID_g           = H5I_INVALID_HID;
 hid_t H5P_LST_ATTRIBUTE_CREATE_ID_g     = H5I_INVALID_HID;
 hid_t H5P_LST_ATTRIBUTE_ACCESS_ID_g     = H5I_INVALID_HID;
 hid_t H5P_LST_OBJECT_COPY_ID_g          = H5I_INVALID_HID;
@@ -314,6 +320,7 @@ H5_DLLVAR const H5P_libclass_t H5P_CLS_STRCRT[1];       /* String create */
 H5_DLLVAR const H5P_libclass_t H5P_CLS_GCRT[1];         /* Group create */
 H5_DLLVAR const H5P_libclass_t H5P_CLS_FCRT[1];         /* File creation */
 H5_DLLVAR const H5P_libclass_t H5P_CLS_DCRT[1];         /* Dataset creation */
+H5_DLLVAR const H5P_libclass_t H5P_CLS_MCRT[1];         /* Map creation */
 H5_DLLVAR const H5P_libclass_t H5P_CLS_DXFR[1];         /* Data transfer */
 H5_DLLVAR const H5P_libclass_t H5P_CLS_FMNT[1];         /* File mount */
 H5_DLLVAR const H5P_libclass_t H5P_CLS_ACRT[1];         /* Attribute creation */
@@ -352,6 +359,8 @@ static H5P_libclass_t const * const init_class[] = {
     H5P_CLS_FMNT,       /* File mount */
     H5P_CLS_TCRT,       /* Datatype creation */
     H5P_CLS_TACC,       /* Datatype access */
+    H5P_CLS_MCRT,       /* Map creation */
+    H5P_CLS_MACC,       /* Map access */
     H5P_CLS_ACRT,       /* Attribute creation */
     H5P_CLS_AACC,       /* Attribute access */
     H5P_CLS_LCRT,       /* Link creation */
@@ -431,7 +440,7 @@ H5P__init_package(void)
     FUNC_ENTER_PACKAGE
 
     /* Sanity check */
-    HDcompile_assert(H5P_TYPE_VOL_INITIALIZE == (H5P_TYPE_MAX_TYPE - 1));
+    HDcompile_assert(H5P_TYPE_MAP_ACCESS == (H5P_TYPE_MAX_TYPE - 1));
 
     /*
      * Initialize the Generic Property class & object groups.
@@ -442,8 +451,8 @@ H5P__init_package(void)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTINIT, FAIL, "unable to initialize ID group")
 
     /* Repeatedly pass over the list of property list classes for the library,
-     *  initializing each class if it's parent class is initialized, until no
-     *  more progress is made.
+     * initializing each class if its parent class is initialized, until no
+     * more progress is made.
      */
     tot_init = 0;
     do {
@@ -547,6 +556,8 @@ H5P_term_package(void)
                         H5P_LST_GROUP_ACCESS_ID_g =
                         H5P_LST_DATATYPE_CREATE_ID_g =
                         H5P_LST_DATATYPE_ACCESS_ID_g =
+                        H5P_LST_MAP_CREATE_ID_g =
+                        H5P_LST_MAP_ACCESS_ID_g =
                         H5P_LST_ATTRIBUTE_CREATE_ID_g =
                         H5P_LST_ATTRIBUTE_ACCESS_ID_g =
                         H5P_LST_OBJECT_COPY_ID_g =
@@ -574,6 +585,8 @@ H5P_term_package(void)
                         H5P_CLS_GROUP_ACCESS_g =
                         H5P_CLS_DATATYPE_CREATE_g =
                         H5P_CLS_DATATYPE_ACCESS_g =
+                        H5P_CLS_MAP_CREATE_g =
+                        H5P_CLS_MAP_ACCESS_g =
                         H5P_CLS_STRING_CREATE_g =
                         H5P_CLS_ATTRIBUTE_CREATE_g =
                         H5P_CLS_ATTRIBUTE_ACCESS_g =
@@ -594,6 +607,8 @@ H5P_term_package(void)
                         H5P_CLS_GROUP_ACCESS_ID_g =
                         H5P_CLS_DATATYPE_CREATE_ID_g =
                         H5P_CLS_DATATYPE_ACCESS_ID_g =
+                        H5P_CLS_MAP_CREATE_ID_g =
+                        H5P_CLS_MAP_ACCESS_ID_g =
                         H5P_CLS_STRING_CREATE_ID_g =
                         H5P_CLS_ATTRIBUTE_CREATE_ID_g =
                         H5P_CLS_ATTRIBUTE_ACCESS_ID_g =
@@ -5437,8 +5452,9 @@ H5P__new_plist_of_type(H5P_plist_type_t type)
 
     FUNC_ENTER_PACKAGE
 
-    /* Sanity check */
-    HDassert(type >= H5P_TYPE_USER && type < H5P_TYPE_MAX_TYPE);
+    /* Sanity checks */
+    HDcompile_assert(H5P_TYPE_MAP_ACCESS == (H5P_TYPE_MAX_TYPE - 1));
+    HDassert(type >= H5P_TYPE_USER && type <= H5P_TYPE_MAP_ACCESS);
 
     /* Check arguments */
     if(type == H5P_TYPE_USER)
@@ -5492,6 +5508,14 @@ H5P__new_plist_of_type(H5P_plist_type_t type)
             class_id = H5P_CLS_DATATYPE_ACCESS_ID_g;
             break;
 
+        case H5P_TYPE_MAP_CREATE:
+            class_id = H5P_CLS_MAP_CREATE_ID_g;
+            break;
+
+        case H5P_TYPE_MAP_ACCESS:
+            class_id = H5P_CLS_MAP_ACCESS_ID_g;
+            break;
+
         case H5P_TYPE_STRING_CREATE:
             class_id = H5P_CLS_STRING_CREATE_ID_g;
             break;
diff --git a/src/H5Pmapl.c b/src/H5Pmapl.c
new file mode 100644
index 0000000..fe5be0f
--- /dev/null
+++ b/src/H5Pmapl.c
@@ -0,0 +1,217 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*-------------------------------------------------------------------------
+ *
+ * Purpose:        Map access property list class routines
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/****************/
+/* Module Setup */
+/****************/
+
+#include "H5Pmodule.h"          /* This source code file is part of the H5P module */
+
+
+/***********/
+/* Headers */
+/***********/
+#include "H5private.h"          /* Generic Functions                        */
+#include "H5Mprivate.h"         /* Maps                                     */
+#include "H5Eprivate.h"         /* Error handling                           */
+#include "H5Iprivate.h"         /* IDs                                      */
+#include "H5Ppkg.h"             /* Property lists                           */
+
+
+/****************/
+/* Local Macros */
+/****************/
+
+/* ========= Map Access properties ============ */
+/* Definitions for key prefetch size */
+#define H5M_ACS_KEY_PREFETCH_SIZE_SIZE          sizeof(size_t)
+#define H5M_ACS_KEY_PREFETCH_SIZE_DEF           (size_t)(16 * 1024)
+#define H5M_ACS_KEY_PREFETCH_SIZE_ENC           H5P__encode_size_t
+#define H5M_ACS_KEY_PREFETCH_SIZE_DEC           H5P__decode_size_t
+/* Definition for key prefetch buffer size */
+#define H5M_ACS_KEY_ALLOC_SIZE_SIZE             sizeof(size_t)
+#define H5M_ACS_KEY_ALLOC_SIZE_DEF          (size_t)(1024 * 1024)
+#define H5M_ACS_KEY_ALLOC_SIZE_ENC          H5P__encode_size_t
+#define H5M_ACS_KEY_ALLOC_SIZE_DEC          H5P__decode_size_t
+
+
+/******************/
+/* Local Typedefs */
+/******************/
+
+
+/********************/
+/* Package Typedefs */
+/********************/
+
+
+/********************/
+/* Local Prototypes */
+/********************/
+
+/* Property class callbacks */
+static herr_t H5P__macc_reg_prop(H5P_genclass_t *pclass);
+
+
+/*********************/
+/* Package Variables */
+/*********************/
+
+/* Map access property list class library initialization object */
+const H5P_libclass_t H5P_CLS_MACC[1] = {{
+    "map access",               /* Class name for debugging     */
+    H5P_TYPE_MAP_ACCESS,        /* Class type                   */
+
+    &H5P_CLS_LINK_ACCESS_g,          /* Parent class                 */
+    &H5P_CLS_MAP_ACCESS_g,          /* Pointer to class             */
+    &H5P_CLS_MAP_ACCESS_ID_g,       /* Pointer to class ID          */
+    &H5P_LST_MAP_ACCESS_ID_g,       /* Pointer to default property list ID */
+    H5P__macc_reg_prop,             /* Default property registration routine */
+
+    NULL,                /* Class creation callback      */
+    NULL,                /* Class creation callback info */
+    NULL,                /* Class copy callback          */
+    NULL,                /* Class copy callback info     */
+    NULL,                /* Class close callback         */
+    NULL                 /* Class close callback info    */
+}};
+
+
+/*****************************/
+/* Library Private Variables */
+/*****************************/
+
+
+/*******************/
+/* Local Variables */
+/*******************/
+
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5P__macc_reg_prop
+ *
+ * Purpose:     Register the map access property list class's
+ *              properties
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5P__macc_reg_prop(H5P_genclass_t *pclass)
+{
+    size_t key_prefetch_size = H5M_ACS_KEY_PREFETCH_SIZE_DEF;   /* Default key prefetch size for iteration */
+    size_t key_alloc_size = H5M_ACS_KEY_ALLOC_SIZE_DEF;         /* Default key prefetch allocation size for iteration */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Register the key prefetch size for iteration */
+    if(H5P__register_real(pclass, H5M_ACS_KEY_PREFETCH_SIZE_NAME, H5M_ACS_KEY_PREFETCH_SIZE_SIZE, &key_prefetch_size,
+             NULL, NULL, NULL, H5M_ACS_KEY_PREFETCH_SIZE_ENC, H5M_ACS_KEY_PREFETCH_SIZE_DEC, NULL, NULL, NULL, NULL) < 0)
+         HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
+
+    /* Register the key prefetch allocation size for iteration */
+    if(H5P__register_real(pclass, H5M_ACS_KEY_ALLOC_SIZE_NAME, H5M_ACS_KEY_ALLOC_SIZE_SIZE, &key_alloc_size,
+             NULL, NULL, NULL, H5M_ACS_KEY_ALLOC_SIZE_ENC, H5M_ACS_KEY_ALLOC_SIZE_DEC, NULL, NULL, NULL, NULL) < 0)
+         HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5P__macc_reg_prop() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Pset_map_iterate_hints
+ *
+ * Purpose:     H5Pset_map_iterate_hints adjusts the behavior of
+ *              H5Miterate when prefetching keys for iteration. The
+ *              KEY_PREFETCH_SIZE parameter specifies the number of keys
+ *              to prefetch at a time during iteration. The KEY_ALLOC_SIZE
+ *              parameter specifies the initial size of the buffer
+ *              allocated to hold these prefetched keys. If this buffer is
+ *              too small it will be reallocated to a larger size, though
+ *              this may result in an additional I/O.
+ *
+ *              Move to DAOS VOL code? DSINC
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pset_map_iterate_hints(hid_t mapl_id, size_t key_prefetch_size, size_t key_alloc_size)
+{
+    H5P_genplist_t *plist;      /* Property list pointer */
+    herr_t ret_value = SUCCEED; /* return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE3("e", "izz", mapl_id, key_prefetch_size, key_alloc_size);
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(mapl_id, H5P_MAP_ACCESS)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
+
+    /* Set sizes */
+    if(H5P_set(plist, H5M_ACS_KEY_PREFETCH_SIZE_NAME, &key_prefetch_size) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET,FAIL, "can't set key prefetch size");
+    if(H5P_set(plist, H5M_ACS_KEY_ALLOC_SIZE_NAME, &key_alloc_size) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET,FAIL, "can't set key allocation size");
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pset_map_iterate_hints() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Pget_map_iterate_hints
+ *
+ * Purpose:     Returns the map iterate hints, KEY_PREFETCH_SIZE and
+ *              KEY_ALLOC_SIZE, as set by H5Pset_map_iterate_hints.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_map_iterate_hints(hid_t mapl_id, size_t *key_prefetch_size, size_t *key_alloc_size)
+{
+    H5P_genplist_t *plist;      /* Property list pointer */
+    herr_t ret_value = SUCCEED; /* return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE3("e", "i*z*z", mapl_id, key_prefetch_size, key_alloc_size);
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(mapl_id, H5P_MAP_ACCESS)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
+
+    /* Get the properties */
+    if(key_prefetch_size) {
+        if(H5P_get(plist, H5M_ACS_KEY_PREFETCH_SIZE_NAME, key_prefetch_size) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get key prefetch size");
+    } /* end if */
+    if(key_alloc_size) {
+        if(H5P_get(plist, H5M_ACS_KEY_ALLOC_SIZE_NAME, key_alloc_size) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get key allocation size");
+    } /* end if */
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_map_iterate_hints() */
+
diff --git a/src/H5Pmcpl.c b/src/H5Pmcpl.c
new file mode 100644
index 0000000..41a6659
--- /dev/null
+++ b/src/H5Pmcpl.c
@@ -0,0 +1,115 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*-------------------------------------------------------------------------
+ *
+ * Created:     H5Pmcpl.c
+ *
+ * Purpose:     Map creation property list class routines
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/****************/
+/* Module Setup */
+/****************/
+
+#include "H5Pmodule.h"          /* This source code file is part of the H5P module */
+
+
+/***********/
+/* Headers */
+/***********/
+#include "H5private.h"          /* Generic Functions                        */
+#include "H5Mprivate.h"         /* Maps                                     */
+#include "H5Eprivate.h"         /* Error handling                           */
+#include "H5Iprivate.h"         /* IDs                                      */
+#include "H5Ppkg.h"             /* Property lists                           */
+
+
+/****************/
+/* Local Macros */
+/****************/
+
+
+/******************/
+/* Local Typedefs */
+/******************/
+
+
+/********************/
+/* Package Typedefs */
+/********************/
+
+
+/********************/
+/* Local Prototypes */
+/********************/
+
+/* Property class callbacks */
+static herr_t H5P__mcrt_reg_prop(H5P_genclass_t *pclass);
+
+
+/*********************/
+/* Package Variables */
+/*********************/
+
+/* Map create property list class library initialization object */
+const H5P_libclass_t H5P_CLS_MCRT[1] = {{
+    "map create",               /* Class name for debugging     */
+    H5P_TYPE_MAP_CREATE,        /* Class type                   */
+
+    &H5P_CLS_OBJECT_CREATE_g,   /* Parent class                 */
+    &H5P_CLS_MAP_CREATE_g,      /* Pointer to class             */
+    &H5P_CLS_MAP_CREATE_ID_g,   /* Pointer to class ID          */
+    &H5P_LST_MAP_CREATE_ID_g,   /* Pointer to default property list ID */
+    H5P__mcrt_reg_prop,         /* Default property registration routine */
+
+    NULL,		        /* Class creation callback      */
+    NULL,		        /* Class creation callback info */
+    NULL,                       /* Class copy callback          */
+    NULL,		        /* Class copy callback info     */
+    NULL,                       /* Class close callback         */
+    NULL 		        /* Class close callback info    */
+}};
+
+
+/*****************************/
+/* Library Private Variables */
+/*****************************/
+
+
+/***************************/
+/* Local Private Variables */
+/***************************/
+
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5P__mcrt_reg_prop
+ *
+ * Purpose:     Register the map creation property list class's properties
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5P__mcrt_reg_prop(H5P_genclass_t H5_ATTR_UNUSED *pclass)
+{
+    herr_t ret_value   = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_STATIC_NOERR
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5P__mcrt_reg_prop() */
+
diff --git a/src/H5Pprivate.h b/src/H5Pprivate.h
index 07910c3..9fc1acc 100644
--- a/src/H5Pprivate.h
+++ b/src/H5Pprivate.h
@@ -79,6 +79,8 @@ typedef enum H5P_plist_type_t {
     H5P_TYPE_LINK_ACCESS       = 17,
     H5P_TYPE_ATTRIBUTE_ACCESS  = 18,
     H5P_TYPE_VOL_INITIALIZE    = 19,
+    H5P_TYPE_MAP_CREATE        = 20,
+    H5P_TYPE_MAP_ACCESS        = 21,
     H5P_TYPE_MAX_TYPE
 } H5P_plist_type_t;
 
@@ -125,6 +127,8 @@ H5_DLLVAR H5P_genclass_t *H5P_CLS_GROUP_CREATE_g;
 H5_DLLVAR H5P_genclass_t *H5P_CLS_GROUP_ACCESS_g;
 H5_DLLVAR H5P_genclass_t *H5P_CLS_DATATYPE_CREATE_g;
 H5_DLLVAR H5P_genclass_t *H5P_CLS_DATATYPE_ACCESS_g;
+H5_DLLVAR H5P_genclass_t *H5P_CLS_MAP_CREATE_g;
+H5_DLLVAR H5P_genclass_t *H5P_CLS_MAP_ACCESS_g;
 H5_DLLVAR H5P_genclass_t *H5P_CLS_ATTRIBUTE_CREATE_g;
 H5_DLLVAR H5P_genclass_t *H5P_CLS_ATTRIBUTE_ACCESS_g;
 H5_DLLVAR H5P_genclass_t *H5P_CLS_OBJECT_COPY_g;
@@ -139,6 +143,7 @@ H5_DLLVAR const struct H5P_libclass_t H5P_CLS_AACC[1];  /* Attribute access */
 H5_DLLVAR const struct H5P_libclass_t H5P_CLS_DACC[1];  /* Dataset access */
 H5_DLLVAR const struct H5P_libclass_t H5P_CLS_GACC[1];  /* Group access */
 H5_DLLVAR const struct H5P_libclass_t H5P_CLS_TACC[1];  /* Named datatype access */
+H5_DLLVAR const struct H5P_libclass_t H5P_CLS_MACC[1];  /* Map access */
 H5_DLLVAR const struct H5P_libclass_t H5P_CLS_FACC[1];  /* File access */
 H5_DLLVAR const struct H5P_libclass_t H5P_CLS_OCPY[1];  /* Object copy */
 
diff --git a/src/H5Ppublic.h b/src/H5Ppublic.h
index cad2071..43e477a 100644
--- a/src/H5Ppublic.h
+++ b/src/H5Ppublic.h
@@ -62,6 +62,8 @@
 #define H5P_GROUP_ACCESS        (H5OPEN H5P_CLS_GROUP_ACCESS_ID_g)
 #define H5P_DATATYPE_CREATE     (H5OPEN H5P_CLS_DATATYPE_CREATE_ID_g)
 #define H5P_DATATYPE_ACCESS     (H5OPEN H5P_CLS_DATATYPE_ACCESS_ID_g)
+#define H5P_MAP_CREATE          (H5OPEN H5P_CLS_MAP_CREATE_ID_g)
+#define H5P_MAP_ACCESS          (H5OPEN H5P_CLS_MAP_ACCESS_ID_g)
 #define H5P_STRING_CREATE       (H5OPEN H5P_CLS_STRING_CREATE_ID_g)
 #define H5P_ATTRIBUTE_CREATE    (H5OPEN H5P_CLS_ATTRIBUTE_CREATE_ID_g)
 #define H5P_ATTRIBUTE_ACCESS    (H5OPEN H5P_CLS_ATTRIBUTE_ACCESS_ID_g)
@@ -83,6 +85,8 @@
 #define H5P_GROUP_ACCESS_DEFAULT       (H5OPEN H5P_LST_GROUP_ACCESS_ID_g)
 #define H5P_DATATYPE_CREATE_DEFAULT    (H5OPEN H5P_LST_DATATYPE_CREATE_ID_g)
 #define H5P_DATATYPE_ACCESS_DEFAULT    (H5OPEN H5P_LST_DATATYPE_ACCESS_ID_g)
+#define H5P_MAP_CREATE_DEFAULT         (H5OPEN H5P_LST_MAP_CREATE_ID_g)
+#define H5P_MAP_ACCESS_DEFAULT         (H5OPEN H5P_LST_MAP_ACCESS_ID_g)
 #define H5P_ATTRIBUTE_CREATE_DEFAULT   (H5OPEN H5P_LST_ATTRIBUTE_CREATE_ID_g)
 #define H5P_ATTRIBUTE_ACCESS_DEFAULT   (H5OPEN H5P_LST_ATTRIBUTE_ACCESS_ID_g)
 #define H5P_OBJECT_COPY_DEFAULT        (H5OPEN H5P_LST_OBJECT_COPY_ID_g)
@@ -191,6 +195,8 @@ H5_DLLVAR hid_t H5P_CLS_GROUP_CREATE_ID_g;
 H5_DLLVAR hid_t H5P_CLS_GROUP_ACCESS_ID_g;
 H5_DLLVAR hid_t H5P_CLS_DATATYPE_CREATE_ID_g;
 H5_DLLVAR hid_t H5P_CLS_DATATYPE_ACCESS_ID_g;
+H5_DLLVAR hid_t H5P_CLS_MAP_CREATE_ID_g;
+H5_DLLVAR hid_t H5P_CLS_MAP_ACCESS_ID_g;
 H5_DLLVAR hid_t H5P_CLS_STRING_CREATE_ID_g;
 H5_DLLVAR hid_t H5P_CLS_ATTRIBUTE_CREATE_ID_g;
 H5_DLLVAR hid_t H5P_CLS_ATTRIBUTE_ACCESS_ID_g;
@@ -211,6 +217,8 @@ H5_DLLVAR hid_t H5P_LST_GROUP_CREATE_ID_g;
 H5_DLLVAR hid_t H5P_LST_GROUP_ACCESS_ID_g;
 H5_DLLVAR hid_t H5P_LST_DATATYPE_CREATE_ID_g;
 H5_DLLVAR hid_t H5P_LST_DATATYPE_ACCESS_ID_g;
+H5_DLLVAR hid_t H5P_LST_MAP_CREATE_ID_g;
+H5_DLLVAR hid_t H5P_LST_MAP_ACCESS_ID_g;
 H5_DLLVAR hid_t H5P_LST_ATTRIBUTE_CREATE_ID_g;
 H5_DLLVAR hid_t H5P_LST_ATTRIBUTE_ACCESS_ID_g;
 H5_DLLVAR hid_t H5P_LST_OBJECT_COPY_ID_g;
@@ -491,6 +499,12 @@ H5_DLL herr_t H5Pget_est_link_info(hid_t plist_id, unsigned *est_num_entries /*
 H5_DLL herr_t H5Pset_link_creation_order(hid_t plist_id, unsigned crt_order_flags);
 H5_DLL herr_t H5Pget_link_creation_order(hid_t plist_id, unsigned *crt_order_flags /* out */);
 
+/* Map access property list (MAPL) routines */
+#ifdef H5_HAVE_MAP_API
+H5_DLL herr_t H5Pset_map_iterate_hints(hid_t mapl_id, size_t key_prefetch_size, size_t key_alloc_size);
+H5_DLL herr_t H5Pget_map_iterate_hints(hid_t mapl_id, size_t *key_prefetch_size /*out*/, size_t *key_alloc_size /*out*/);
+#endif /*  H5_HAVE_MAP_API */
+
 /* String creation property list (STRCPL) routines */
 H5_DLL herr_t H5Pset_char_encoding(hid_t plist_id, H5T_cset_t encoding);
 H5_DLL herr_t H5Pget_char_encoding(hid_t plist_id, H5T_cset_t *encoding /*out*/);
diff --git a/src/H5Rint.c b/src/H5Rint.c
index 2355ec1..07efae2 100644
--- a/src/H5Rint.c
+++ b/src/H5Rint.c
@@ -472,6 +472,9 @@ H5R__dereference(H5F_t *file, hid_t oapl_id, H5R_type_t ref_type, const void *_r
             break;
         }
 
+        case H5O_TYPE_MAP:
+            HGOTO_ERROR(H5E_REFERENCE, H5E_BADTYPE, H5I_INVALID_HID, "maps not supported in native VOL connector")
+
         case H5O_TYPE_UNKNOWN:
         case H5O_TYPE_NTYPES:
         default:
diff --git a/src/H5T.c b/src/H5T.c
index 8eada62..6ef9478 100644
--- a/src/H5T.c
+++ b/src/H5T.c
@@ -1740,6 +1740,7 @@ H5Tcopy(hid_t obj_id)
         case H5I_GROUP:
         case H5I_DATASPACE:
         case H5I_ATTR:
+        case H5I_MAP:
         case H5I_VFL:
         case H5I_VOL:
         case H5I_GENPROP_CLS:
diff --git a/src/H5VLcallback.c b/src/H5VLcallback.c
index 696ccab..0131f0e 100644
--- a/src/H5VLcallback.c
+++ b/src/H5VLcallback.c
@@ -6562,3 +6562,114 @@ done:
     FUNC_LEAVE_API_NOINIT(ret_value)
 } /* end H5VLrequest_free() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL__optional
+ *
+ * Purpose:     Optional operation specific to connectors.
+ *
+ * Return:      Success:    Non-negative
+ *              Failure:    Negative
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5VL__optional(void *obj, const H5VL_class_t *cls, hid_t dxpl_id,
+    void **req, va_list arguments)
+{
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Check if the corresponding VOL callback exists */
+    if(NULL == cls->optional)
+        HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "VOL connector has no 'optional' method")
+
+    /* Call the corresponding VOL callback */
+    if((ret_value = (cls->optional)(obj, dxpl_id, req, arguments)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, ret_value, "unable to execute optional callback")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL__optional() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL_optional
+ *
+ * Purpose:     Optional operation specific to connectors.
+ *
+ * Return:      Success:    Non-negative
+ *              Failure:    Negative
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VL_optional(const H5VL_object_t *vol_obj, hid_t dxpl_id,
+    void **req, ...)
+{
+    va_list arguments;                  /* Argument list passed from the API call */
+    hbool_t arg_started = FALSE;        /* Whether the va_list has been started */
+    hbool_t vol_wrapper_set = FALSE;    /* Whether the VOL object wrapping context was set up */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Set wrapper info in API context */
+    if(H5VL_set_vol_wrapper(vol_obj->data, vol_obj->connector) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTSET, FAIL, "can't set VOL wrapper info")
+    vol_wrapper_set = TRUE;
+
+    /* Call the corresponding internal VOL routine */
+    HDva_start(arguments, req);
+    arg_started = TRUE;
+    if((ret_value = H5VL__optional(vol_obj->data, vol_obj->connector->cls, dxpl_id, req, arguments)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "unable to execute optional callback")
+
+done:
+    /* End access to the va_list, if we started it */
+    if(arg_started)
+        HDva_end(arguments);
+
+    /* Reset object wrapping info in API context */
+    if(vol_wrapper_set && H5VL_reset_vol_wrapper() < 0)
+        HDONE_ERROR(H5E_VOL, H5E_CANTRESET, ret_value, "can't reset VOL wrapper info")
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_optional() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VLoptional
+ *
+ * Purpose:     Performs an optional connector-specific operation
+ *
+ * Return:      Success:    Non-negative
+ *              Failure:    Negative
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VLoptional(void *obj, hid_t connector_id, hid_t dxpl_id, void **req,
+    va_list arguments)
+{
+    H5VL_class_t *cls;                  /* VOL connector's class struct */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_API_NOINIT
+    H5TRACE5("e", "*xii**xx", obj, connector_id, dxpl_id, req, arguments);
+
+    /* Check args and get class pointer */
+    if(NULL == obj)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (cls = (H5VL_class_t *)H5I_object_verify(connector_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL connector ID")
+
+    /* Call the corresponding internal VOL routine */
+    if((ret_value = H5VL__optional(obj, cls, dxpl_id, req, arguments)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, ret_value, "unable to execute optional callback")
+
+done:
+    FUNC_LEAVE_API_NOINIT(ret_value)
+} /* end H5VLoptional() */
+
diff --git a/src/H5VLconnector.h b/src/H5VLconnector.h
index 9de518f..98bc521 100644
--- a/src/H5VLconnector.h
+++ b/src/H5VLconnector.h
@@ -314,7 +314,7 @@ typedef struct H5VL_group_class_t {
 /* H5L routines */
 typedef struct H5VL_link_class_t {
     herr_t (*create)(H5VL_link_create_type_t create_type, void *obj, const H5VL_loc_params_t *loc_params,
-            hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req, va_list argumenmts);
+            hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req, va_list arguments);
     herr_t (*copy)(void *src_obj, const H5VL_loc_params_t *loc_params1,
                    void *dst_obj, const H5VL_loc_params_t *loc_params2,
                    hid_t lcpl, hid_t lapl, hid_t dxpl_id, void **req);
diff --git a/src/H5VLint.c b/src/H5VLint.c
index 884b2f6..f9262f4 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -552,7 +552,8 @@ H5VL__new_vol_obj(H5I_type_t type, void *object, H5VL_t *vol_connector, hbool_t
     HDassert(vol_connector);
 
     /* Make sure type number is valid */
-    if(type != H5I_ATTR && type != H5I_DATASET && type != H5I_DATATYPE && type != H5I_FILE && type != H5I_GROUP)
+    if(type != H5I_ATTR && type != H5I_DATASET && type != H5I_DATATYPE
+            && type != H5I_FILE && type != H5I_GROUP && type != H5I_MAP)
         HGOTO_ERROR(H5E_VOL, H5E_BADVALUE, NULL, "invalid type number")
 
     /* Create the new VOL object */
@@ -1408,6 +1409,7 @@ H5VL__object(hid_t id, H5I_type_t obj_type)
         case H5I_DATASET:
         case H5I_FILE:            
         case H5I_ATTR:
+        case H5I_MAP:
             /* get the object */
             if (NULL == (vol_obj = (H5VL_object_t *)H5I_object(id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "invalid identifier")
diff --git a/src/H5VLprivate.h b/src/H5VLprivate.h
index 91fa762..1752b0c 100644
--- a/src/H5VLprivate.h
+++ b/src/H5VLprivate.h
@@ -193,5 +193,8 @@ H5_DLL herr_t H5VL_request_specific(const H5VL_object_t *vol_obj, H5VL_request_s
 H5_DLL herr_t H5VL_request_optional(const H5VL_object_t *vol_obj, ...);
 H5_DLL herr_t H5VL_request_free(const H5VL_object_t *vol_obj);
 
+/* Generic functions */
+H5_DLL herr_t H5VL_optional(const H5VL_object_t *vol_obj, hid_t dxpl_id,void **req, ...);
+
 #endif /* _H5VLprivate_H */
 
diff --git a/src/H5err.txt b/src/H5err.txt
index d4edfba..9fec521 100644
--- a/src/H5err.txt
+++ b/src/H5err.txt
@@ -78,6 +78,7 @@ MAJOR, H5E_FARRAY, Fixed Array
 MAJOR, H5E_PLUGIN, Plugin for dynamically loaded library
 MAJOR, H5E_PAGEBUF, Page Buffering
 MAJOR, H5E_CONTEXT, API Context
+MAJOR, H5E_MAP, Map
 MAJOR, H5E_NONE_MAJOR, No error
 
 # Sections (for grouping minor errors)
diff --git a/src/H5private.h b/src/H5private.h
index a897fb9..537e860 100644
--- a/src/H5private.h
+++ b/src/H5private.h
@@ -1721,6 +1721,7 @@ typedef enum {
     H5_PKG_HG,      /* Global heaps             */
     H5_PKG_HL,      /* Local heaps              */
     H5_PKG_I,       /* IDs                      */
+    H5_PKG_M,       /* Maps                     */
     H5_PKG_MF,      /* File memory management   */
     H5_PKG_MM,      /* Core memory management   */
     H5_PKG_O,       /* Object headers           */
@@ -2637,6 +2638,8 @@ H5_DLL int H5G_term_package(void);
 H5_DLL int H5G_top_term_package(void);
 H5_DLL int H5I_term_package(void);
 H5_DLL int H5L_term_package(void);
+H5_DLL int H5M_term_package(void);
+H5_DLL int H5M_top_term_package(void);
 H5_DLL int H5P_term_package(void);
 H5_DLL int H5PL_term_package(void);
 H5_DLL int H5R_term_package(void);
diff --git a/src/H5trace.c b/src/H5trace.c
index c5d14f5..de761f8 100644
--- a/src/H5trace.c
+++ b/src/H5trace.c
@@ -1359,6 +1359,10 @@ H5_trace(const double *returning, const char *func, const char *type, ...)
                                 HDfprintf(out, "%ld (attr)", (long)obj);
                                 break;
 
+                            case H5I_MAP:
+                                HDfprintf(out, "%ld (map)", (long)obj);
+                                break;
+
                             case H5I_VFL:
                                 HDfprintf(out, "%ld (file driver)", (long)obj);
                                 break;
@@ -1544,6 +1548,10 @@ H5_trace(const double *returning, const char *func, const char *type, ...)
                                     HDfprintf(out, "H5I_ATTR");
                                     break;
 
+                                case H5I_MAP:
+                                    HDfprintf(out, "H5I_MAP");
+                                    break;
+
                                 case H5I_VFL:
                                     HDfprintf(out, "H5I_VFL");
                                     break;
@@ -1799,8 +1807,12 @@ H5_trace(const double *returning, const char *func, const char *type, ...)
                                     HDfprintf(out, "H5O_TYPE_NAMED_DATATYPE");
                                     break;
 
+                                case H5O_TYPE_MAP:
+                                    HDfprintf(out, "H5O_TYPE_MAP");
+                                    break;
+
                                 case H5O_TYPE_NTYPES:
-                                    HDfprintf(out, "H5O_TYPE_TYPES");
+                                    HDfprintf(out, "H5O_TYPE_NTYPES");
                                     break;
 
                                 default:
diff --git a/src/Makefile.am b/src/Makefile.am
index f737d5d..1e6578e 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -78,6 +78,7 @@ libhdf5_la_SOURCES= H5.c H5checksum.c H5dbg.c H5system.c H5timer.c H5trace.c \
         H5HG.c H5HGcache.c H5HGdbg.c H5HGquery.c \
         H5HL.c H5HLcache.c H5HLdbg.c H5HLint.c H5HLprfx.c H5HLdblk.c\
         H5HP.c H5I.c H5Itest.c H5L.c H5Lexternal.c H5lib_settings.c \
+        H5M.c \
         H5MF.c H5MFaggr.c H5MFdbg.c H5MFsection.c \
         H5MM.c H5MP.c H5MPtest.c \
         H5O.c H5Odeprec.c H5Oainfo.c H5Oalloc.c H5Oattr.c \
@@ -95,8 +96,9 @@ libhdf5_la_SOURCES= H5.c H5checksum.c H5dbg.c H5system.c H5timer.c H5trace.c \
         H5P.c H5Pacpl.c H5Pdapl.c H5Pdcpl.c \
         H5Pdeprec.c H5Pdxpl.c H5Pencdec.c \
         H5Pfapl.c H5Pfcpl.c H5Pfmpl.c \
-        H5Pgcpl.c H5Pint.c \
-        H5Plapl.c H5Plcpl.c H5Pocpl.c H5Pocpypl.c H5Pstrcpl.c H5Ptest.c \
+        H5Pgcpl.c H5Pint.c H5Plapl.c H5Plcpl.c \
+        H5Pmapl.c H5Pmcpl.c H5Pocpl.c H5Pocpypl.c H5Pstrcpl.c \
+        H5Ptest.c \
         H5PB.c \
         H5PL.c H5PLint.c H5PLpath.c H5PLplugin_cache.c \
         H5R.c H5Rint.c H5Rdeprec.c \
@@ -141,7 +143,7 @@ include_HEADERS = hdf5.h H5api_adpt.h H5overflow.h H5pubconf.h H5public.h H5vers
         H5FDfamily.h H5FDhdfs.h H5FDlog.h H5FDmpi.h H5FDmpio.h \
         H5FDmulti.h H5FDros3.h H5FDsec2.h H5FDstdio.h H5FDwindows.h \
         H5Gpublic.h  H5Ipublic.h H5Lpublic.h \
-        H5MMpublic.h H5Opublic.h H5Ppublic.h \
+        H5Mpublic.h H5MMpublic.h H5Opublic.h H5Ppublic.h \
         H5PLextern.h H5PLpublic.h \
         H5Rpublic.h H5Spublic.h H5Tpublic.h \
         H5VLconnector.h H5VLconnector_passthru.h \
diff --git a/src/hdf5.h b/src/hdf5.h
index 2201e9e..8367122 100644
--- a/src/hdf5.h
+++ b/src/hdf5.h
@@ -29,6 +29,7 @@
 #include "H5Gpublic.h"          /* Groups                                   */
 #include "H5Ipublic.h"          /* ID management                            */
 #include "H5Lpublic.h"          /* Links                                    */
+#include "H5Mpublic.h"          /* Maps                                     */
 #include "H5MMpublic.h"         /* Memory management                        */
 #include "H5Opublic.h"          /* Object headers                           */
 #include "H5Ppublic.h"          /* Property lists                           */