Confusion about MQ Put options (IBM MQ)

Question

I am trying to understand some of the IBM MQ put options:

I have used https://www.ibm.com/docs/en/ibm-mq/9.2?topic=interfaces-mqputmessageoptionsnet-class for documentation.

1. It seems that MQPMO_ASYNC_RESPONSE and MQPMO_SYNC_RESPONSE in fact are mutually exclusive, yet these options have to different ID's (bit 12 and bit 13). What does MQ do when both options are set or neither one is set?

2. t seems that MQPMO_SYNCPOINT and MQPMO_NO_SYNCPOINT in fact are mutually exclusive, yet these options have to different ID's (bit 2 and bit 3). What does MQ do when both options are set or neither one is set?

3. MQPMO_RESPONSE_AS_Q_DEF makes things even more confusing for me. As I understand from the documentation this bit defers the control of the requests being synchronous or asynchronous to the queue definition. Therefore ignorning the options set with MQPMO_ASYNC_RESPONSE and MQPMO_SYNC_RESPONSE. But the documentation states the following

For an MQDestination.put call, this option takes the put response type from DEFPRESP attribute of the queue. For an MQQueueManager.put call, this option causes the call to be made synchronously.

And the documentation for DEFRESP at https://www.ibm.com/docs/en/ibm-mq/9.1?topic=queues-defpresp-mqlong is stating this:

The default put response type (DEFPRESP) attribute defines the value used by applications when the PutResponseType within MQPMO has been set to MQPMO_RESPONSE_AS_Q_DEF. This attribute is valid for all queue types.

The value is one of the following:

• SYNC The put operation is issued synchronously returning a response.
• ASYNC The put operation is issued asynchronously, returning a subset of MQMD fields.

But the other documentation says setting this option makes the call synchronous.

So in short: What happens with the seemingly mutually exclusive options and what does the MQPMO_RESPONSE_AS_Q_DEF really do?

Answer 1

If you combine options flags that are not supposed to be combined, such as MQPMO_SYNCPOINT and MQPMO_NO_SYNCPOINT you will be return MQRC_OPTIONS_ERROR on the MQPUT call. you can see the documentation for this in IBM Docs here.

You are correct, the use of MQPMO_RESPONSE_AS_Q_DEF tells the queue manager to take the value for Put Response from the queue attribute DEFPRESP. The queue manager will look up the queue definition, and if it is SYNC it will effectively use MQPMO_SYNC_RESPONSE and if it is ASYNC it will effectively use MQPMO_ASYNC_RESPONSE.

The documentation you pointed us to states the following:-

MQC.MQPMO_RESPONSE_AS_Q_DEF

For an MQDestination.put call, this option takes the put response type from DEFPRESP attribute of the queue.

For an MQQueueManager.put call, this option causes the call to be made synchronously.

I don't know why it would be different depending on the class used, but I can tell you that if the MQPMO_RESPONSE_AS_Q_DEF makes it to the queue manager it will change it as described above. This documentation suggests that the MQQueueManager class is changing it itself which is an odd decision.