The following section describes issues with request-reply processing.
If the maximum wait time is exceeded while waiting for the reply to a request, the request is considered as having failed. The timeout is returned to the collaboration and the flows end up as a failed flow.
Although a timeout was encountered, the request may have been successfully processed by the target application. Restarting the failing flow results in a repetition of the request.
Since the adapter does not maintain a request history it is not capable of detecting duplicate requests. FRONT ARENA, duplicate object requests are not a problem. FRONT ARENA internally converts a second create request for an object into an update, which does not apply any changes to the object. A duplicate update request does not have any effect. A second delete request fails because the object no longer exists.
Recommended action: Check to see whether the environment is still up and running, then, restart the failed flow.
If the reply to a request arrives after the maximum wait time configured for the adapter; it is ignored by the adapter. When a reply message in reply queue is related to a request that already timed out a timeout, a timeout message has been sent to the collaboration before, resulting in a failing flow.
Recommended action: Clean up the reply queue regularly. If failed flows exist, it is possible to use these messages for diagnostic purposes.
A reply indicating that a failed request has the return information in the feedback field, as well as the error message as part of the message body.
Recommended action: The collaboration must handle the error situations documented. For more information, see Configuring the bridge.
When the message cannot be read from the request queue, the adapter terminates. Depending on the adapter's configuration, it can restart automatically. The request flow ends up as a failed flow indicating that there was a queue access problem.
Recommended action: Correct the problem with the WebSphere MQ queue and restart the failed flows.