Chapter 16. Writing a dynamic routing program
Considerations common to all user-replaceable programs
Note that the comments contained in “Chapter 5. General notes about
user-replaceable programs” on page401 apply to this chapter.
This chapter describes the CICS default dynamic routing program and tells you how
to write your own version. It assumes you are familiar with the principles of
transaction routing, distributed program link (DPL), and dynamic routing described
in the
CICS Intercommunication Guide
.
Youcan use the dynamic routing program to route:
vTransactions initiated from user terminals
vTransactions initiated by a subset of terminal-related EXEC CICS START
commands
vProgram-link requests.
For detailed information about which transactions initiated by STARTcommands,
and which program-link requests, are eligible for dynamic routing, see the
CICS
Intercommunication Guide
.
Notes:
1. Youcannot use the
dynamic
routing program—that is, the program named on
the DTRPGM system initialization parameter—to route transactions:
vThat implement CICS business transaction services activities
vThat are initiated by non-terminal-related EXEC CICS STARTcommands.
Toroute these types of transactions you must use the

distributed

routing
program named on the DSRTPGM system initialization parameter. How to write
a distributed routing program is described in “Chapter 17. Writing a distributed
routing program” on page 575.
2. The dynamic routing program and the distributed routing program may, of
course, be the same program.
Important
If you use the CICSPlex® System Manager (CICSPlex SM) product to
manage your CICSplex, you may not need to write a dynamic routing
program. CICSPlex SM provides a fully-functioning dynamic routing program
that supports workload balancing and workload separation. All you have to do
is to tell CICSPlex SM, through its user interface, which regions in the
CICSplex can participate in dynamic routing, and define any transaction
affinities that govern the target regions to which particular transactions must
be routed. For introductory information about CICSPlex SM, see the

CICSPlex

SM Concepts and Planning

manual.
The rest of the chapter is divided into the following sections:
1. “Dynamic transaction routing”
2. “Dynamic routing of DPL requests” on page 557
3. “Parameters passed to the dynamic routing program” on page 562
© Copyright IBM Corp. 1977, 1999 549
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