code: @Override
      public int prepare(final Xid _xid)
      {
          if (VFSStoreResource.LOG.isDebugEnabled())  {
              VFSStoreResource.LOG.debug("prepare (xid=" + _xid + ")");
          }
          return 0;
      }
docs: Ask the resource manager to prepare for a transaction commit of the
  transaction specified in xid (used for 2-phase commits).
  
  @param _xid Xid
  @return always 0