Has the message flow run successfully before?

Sometimes a problem appears in a message flow that has previously run successfully.

• Have you made any changes to the message flow since it last ran successfully?

  If so, it is likely that the error exists somewhere in the new or modified part of the flow. Examine the changes and see if you can find an obvious reason for the problem.

• Have you used all the functions of the message flow before?

  Did the problem occur when you used part of the message flow that had never been invoked before? If so, it is likely that the error exists in that part. Try to find out what the message flow was doing when it failed by using user tracing, trace nodes, and the debugger function of the IBM Integration Toolkit.

  If you have run a message flow successfully on many previous occasions, check the current queue status and the files that were being processed when the error occurred. It is possible that they contain some unusual data value that invokes a rarely-used path in the message flow.

• Does the message flow check all return codes?
  Has your system been changed, perhaps in a minor way, but your message flow does not check the return codes it receives as a result of the change? For example:

  • Does your message flow assume that the queues that it accesses can be shared? If a queue has been redefined as exclusive, can your message flow deal with return codes indicating that it can no longer access that queue?
  • Have any security profiles been changed? A message flow could fail because of a security violation.
• Does the message flow expect particular message formats?

  If a message with an unexpected message format has been put onto a queue (for example, a message from a queue manager on a different operating system) it might require data conversion or a different form of processing. Also, check whether you have changed any of the message formats that are used.

• Does the message flow run on other IBM Integration Bus systems?

  Is there something different about the way that your system is set up that is causing the problem? For example, have the queues been defined with the same maximum message length or priority? Are there differences in the databases used, or their setup?

• Are you using any user-defined extensions?

  There might be translation or compilation problems with loadable implementation library (LIL) files. Before you look at the code, examine the output from the translator, the compiler or assembler, and the linkage editor, to see if any errors have been reported. Fix any errors to make the user-defined extension work.

  If the documentation shows that each of these steps was completed without error, consider the coding logic of the message flow, message set, or user-defined extension. Do the symptoms of the problem indicate which function is failing and, therefore, which piece of code is in error? See User-defined extensions overview for more information.

• Can you see errors from IBM Integration Bus or external resources, such as databases?

  Your message flow might be losing errors because of incorrect use of the failure terminals on built-in nodes. If you use the failure terminals, make sure that you handle errors adequately. See Handling errors in message flows for more information about failure terminals.