A message handler is a CICS® program
that is used to process a web service request during input and to
process the response during output. Message handlers use channels
and containers to interact with one another and with the system.
The message handler interface lets you perform the following tasks
in a message handler program:
- Examine the contents of an XML request or response, without changing
it
- Change the contents of an XML request or response
- In a non-terminal message handler, pass an XML request or response
to the next message handler in the pipeline
- In a terminal message handler, call an application program, and
generate a response
- In the request phase of the pipeline, force a transition to the
response phase, by absorbing the request, and generating a response
- Handle errors
Tip: It is advisable to use the SOAP handlers, <cics_soap_1.1_handler>, <cics_soap_1.2_handler>, <cics_soap_1.1_handler_java>
or <cics_soap_1.2_handler_java>, to work with SOAP messages.
These handlers let you work directly with the major elements in a
SOAP message (the SOAP headers and the SOAP body).
All programs that are used as message handlers are invoked with
the same interface: they are invoked with a
channel that
holds a number of containers. The containers can be categorized as
the following types:
- Control containers
- These are essential to the operation of the pipeline. Message
handlers can use the control containers to modify the sequence in
which subsequent handlers are processed.
- Context containers
- In some situations, message handler programs need information
about the context in which they are invoked. CICS provides
this information in a set of context containers that
are passed to the programs.
Some of the context containers hold
information that you can change in your message handler. For example,
in a service provider pipeline, you can change the user ID and transaction
ID of the target application program by modifying the contents of
the appropriate context containers.
- User containers
- These contain information that one message handler needs to pass
to another. The use of user containers is entirely a matter for the
message handlers.
Restriction: Do not use names that start
with DFH for user containers.
Last updated: Thursday, 27 June 2019