There are two CICS®-supplied user-replaceable programs for dynamic routing:
- The dynamic routing program, DFHDYP
- Can be used to route:
- Transactions started from terminals
- Transactions started by terminal-related START commands
- CICS-to-CICS DPL requests
- Program-link requests received from outside CICS
Bridge 3270 requests
- The distributed routing program, DFHDSRP
- Can be used to route:
- CICS business transaction services processes and activities
- Method requests for enterprise beans and CORBA stateless objects
- Non-terminal-related START requests.
The two routing programs:
- 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.
- Are passed the same communications area. (Certain fields that are meaningful
to one program are not meaningful to the other.)
- 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:
- Use different user-written programs for dynamic routing and distributed
routing.
- Use the same user-written program for both dynamic routing and distributed
routing.
- Use a user-written program for dynamic routing and the CICSPlex® SM routing
program for distributed routing, or vice versa.
It is worth noting two important differences between the dynamic and distributed
routing programs:
- 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.
- 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.
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

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