Two routing programs

There are two CICS®-supplied user-replaceable programs for dynamic routing:

The dynamic routing program, DFHDYP
Can be used to route:
The distributed routing program, DFHDSRP
Can be used to route:

The two routing programs:

  1. Are specified on separate system initialization parameters. You specify the name of your dynamic routing program on the DTRPGM system initialization parameter. You specify the name of your distributed routing program on the DSRTPGM system initialization parameter.
  2. Are passed the same communications area. (Certain fields that are meaningful to one program are not meaningful to the other.)
  3. Are invoked at similar points--for example, for route selection, route selection error, and (optionally) at termination of the routed transaction or program-link request.

Together, these three factors give you a great deal of flexibility. You could, for example, do any of the following:

It is worth noting two important differences between the dynamic and distributed routing programs:

  1. The dynamic routing program is only invoked if the resource (the transaction or program) is defined as DYNAMIC(YES). The distributed routing program, on the other hand, is invoked (for eligible non-terminal-related START requests, BTS activities, and method requests for enterprise beans and CORBA stateless objects) even if the associated transaction is defined as DYNAMIC(NO)--though it cannot route the request. What this means is that the distributed routing program is better able to monitor the effect of statically-routed requests on the relative workloads of the target regions.
  2. Because the dynamic routing program uses the hierarchical "hub" routing model--one routing program controls access to resources on several target regions--the routing program that is invoked at termination of a routed request is the same program that was invoked for route selection.

    The distributed routing program, on the other hand, uses the distributed model, which is a peer-to-peer system; the routing program itself is distributed. The routing program that is invoked at initiation or termination of a routed transaction is not the same program that was invoked for route selection--it is the routing program on the target region.

Start of change Important

If you intend to route from CICS TS for z/OS, Version 3.1 to a CICS Transaction Server for OS/390®, Version 1 Release 3 region (or vice versa), you must ensure that the PTF for CICS APAR PQ 75814 is applied to CICS Transaction Server for OS/390, Version 1 Release 3.

If you use CICSPlex SM for routing, the PTFs for each of the following CICSPlex SM APARs must be applied to each relevant CICSPlex SM release:

CICSPlex SM Version 1 Release 4
PQ80891
CICSPlex SM Version 2 Release 2
PQ80893
CICSPlex SM Version 2 Release 3
PQ81235
End of change

Related concepts
What is dynamic routing?
Two routing models
CICS transaction routing
Defining indirect links for transaction routing
Related tasks
Defining remote resources for transaction routing
Application programming for CICS transaction routing
Related reference
Appendix A. Intercommunication rules and restrictions checklist
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