The HDF5 ADIOS2 VOL enables customized behaviour for a core set of HDF5 functions. 
This VOL is for HDF5 clients to create and access ADIOS2 files through current HDF5 API

There are two ways to use it: via dynamic library loading or explicit linking.

- To use dynamic library loading, set the following env:
  HDF5_VOL_CONNECTOR=ADIOS2_VOL
  HDF5_PLUGIN_PATH=/tmp/adios2_vol/lib/path/

  where /tmp/.. is where this library located

  without code change, ADIOS2 VOL will be loaded at runtime and adios2 file will be used instead of native hdf5 file. 

- To use explicit linking:
  first, include the header: 
     #include <adios2/h5vol/H5Vol.h>
  second, call the set function when H5F is initiated, 
     H5VL_ADIOS2_set(m_fileAccessProperty);
  third, call the unset function when H5F is closed
     H5VL_ADIOS2_unset();


- To choose what ADIOS2 Engine to use, set env variable:
  ADIOS2_ENGINE
(default is BP4)

- Features not in this VOL:
  * hyperslab support
  * HDF5   parameters are not passed down. e.g. compression/decompression
  * ADIOS2 parameters is not setup. 
  * user defined types
  * change of variable extent is not supported in ADIOS2. 


Questions and suggestions:
email to jgu@lbl.gov

