If you plan on using datapower to write a modified value to the AppIdentity MQMD header, ensure that your Put Message Options on your destination are correct.

You want to use “2052” which represents “MQPMO_SET_CONTEXT_ALL” along with “MQPMO_NO_SYNCPOINT”. You need to tell MQ that it should use the message headers from the written message. In Datapower, (for some unknown reason) in the URL Builder for MQ, this is the “User Identity” on/off toggle.

‘No Syncpoint’ tells MQ that this is a single message transaction that isn’t dependent on the writing on subsequent messages. This of it like “I want all 5 messages I write to the queue to be committed all together or none at all”.

If you don’t set your Put Message Options correctly, you won’t see your modified headers written onto the message in the Queue.