If you are using dynamic server selection, the CICS® request exit provides a number
of advantages when compared with the DFHXCURM user replaceable module
(URM).
The CICS request exit is
part of the Gateway daemon and can be used for redirecting requests
over EXCI or IPIC connections. Because the CICS request exit supports
IPIC, you can use it to redirect ECI requests calling CICS channel
based programs and ESI requests which are not supported over EXCI
connections.
The DFHXCURM user replaceable module is used for redirecting requests
over EXCI in a local mode topology. DFHXCURM cannot be used with IPIC
connections.
Benefits of using the CICS request
exit
When implementing dynamic server selection, the CICS request exit provides these
advantages over DFHXCURM:
- The CICS request exit
is integrated with the statistics and request monitoring exits.
- The CICS request
exit is invoked for every transaction rather than at pipe allocation,
and provides the ability to quickly discover when failed CICS servers are restarted.
- CICS Transaction Gateway can
track the number of times a CICS request
exit is called; If the value is greater than the number of transactions
that have been processed, this provides an indication that some requests
were retried.
- CICS Transaction Gateway can
log statistics about the work sent to each CICS server that the CICS request exit selected.
- If a request fails with an error at the start of a transaction,
the CICS request exit can be
called a second time with details of the previous failure.