code: public static String createBrokerIdString(JobID jid, String iterationID, int subtaskIndex) {
  		return jid + "-" + iterationID + "-" + subtaskIndex;
  	}
docs: Creates the identification string with which head and tail task find the shared blocking
  queue for the back channel. The identification string is unique per parallel head/tail pair
  per iteration per job.
  
  @param jid The job ID.
  @param iterationID The id of the iteration in the job.
  @param subtaskIndex The parallel subtask number
  @return The identification string.