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The H5R APIs were extended in HDF5-1.12 to support external references and attributes and to support the Virtual Object Layer (VOL). Information on these changes can be found below:


To support the new reference features several functions were introduced:

  • Create (H5R_CREATE*) functions were added for each reference type:
    • attribute (H5R_CREATE_ATTR)
    • object (H5R_CREATE_OBJECT)
    • dataset region (H5R_CREATE_REGION)

  • A function was added to release a reference (H5R_DESTROY). This is required because a region reference no longer modifies the original file.
  • Functions were added to query references:

  • Other functions were added to simplify or clarify the API.

See the RFC for details on the changes that were made.

HDF5 Library APIs

The H5R functions that were introduce in HDF5-1.12 are described below.

H5R_COPYCopies an existing reference
H5R_CREATE_ATTRCreates an attribute reference
H5R_CREATE_OBJECTCreates an object reference
H5R_CREATE_REGIONCreates a region reference
H5R_DECODEDecodes a reference from a buffer
H5R_DESTROYCloses a reference
H5R_ENCODEEncodes a reference into a buffer
H5R_EQUALDetermines whether two references are equal
H5R_GET_ATTR_NAMERetrieves the attribute name for a referenced object
H5R_GET_FILE_NAMERetrieves the file name for a referenced object
H5R_GET_OBJ_NAMERetrieves the object name for a referenced object
H5R_GET_OBJ_TYPE3Retrieves the type of object that an object reference points to
H5R_GET_TYPERetrieves the type of reference
H5R_OPEN_ATTROpens the referenced HDF5 attribute
H5R_OPEN_OBJECTOpens the referenced HDF5 object
H5R_OPEN_REGIONSets up a dataspace and selection as specified by a region reference

--- Last Modified: September 17, 2019 | 01:56 PM