Metacat

  	if(session == null) {

      throw new InvalidToken("1370", "The session object is null");

    }

    if(pid == null || pid.getValue().trim().equals(""))

    {

      throw new InvalidRequest("1362", "The object identifier is null. " +

        "A valid identifier is required.");

    }

    SystemMetadata sysmeta = getSystemMetadata(session, pid);

    DescribeResponse describeResponse = 

    	new DescribeResponse(sysmeta.getObjectFormat(), 

      sysmeta.getSize(), sysmeta.getDateSysMetadataModified(), sysmeta.getChecksum());

    return describeResponse;