Error handling by the CICS bridge

 

Errors detected by the CICS bridge cause the bridge to:

Any further request messages in the same unit of work are removed from the request queue and copied to the backout requeue or dead-letter queue, either during error processing for this unit of work or at the next initialization of the monitor. No further error messages are generated.

If sending a reply message fails, the CICS bridge puts the reply on the dead-letter queue, passing identity context from the CICS bridge request queue. A unit of work is not backed out if the reply message is successfully put on the dead-letter queue. Failure to put a reply message on the dead-letter queue is treated as a request error, and the unit of work is backed out.

If the CICS bridge fails to put a request message on the dead-letter queue, the CICS bridge task abends and leaves the CICS bridge monitor to process the error. If the monitor fails to move a persistent request message to the dead-letter queue, the monitor leaves the message on the request queue, non-persistent messages are discarded .

Failure to put an error reply is ignored by the CICS bridge. The request message has already been copied to the dead-letter queue and the unit of work has been backed out by WebSphere MQ.

Figure 1 shows what happens when an error occurs in a unit of work.

Figure 1. User program abends (only program in the unit of work)

In this figure:

The monitor task browses the request queue awaiting the arrival of a message. When a message arrives, it:

The CICS bridge task

When these tasks are complete, the user program abends.

The CICS bridge task abend handler is driven, which:

If the request message includes the name of a reply-to queue, the abend handler:

 

Parent topic:

Information applicable to both DPL and 3270


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