Capture message ID / IDOC numbers (IDOC-XI-HTTP)

Hi! I am running a IDOC-XI-HTTP scenario and am trying to figure out a way to capture the XI message ID and the IDOC number to which it is linked and send this to back to the source system such that the user can see the data. This is needed to support easy follow up on issues.

Does anyone have experience on how to grab this kind of data at runtime? I know I can output the message as a file to the filesystem but this is not an option.

Any bright ideas would be much appreciated!

Thx, Duncan