You can distribute applications that use CICS® Web support in a CICSPlex® using
the following methods individually, or in combination:
- You can use network load balancing to distribute requests from Web clients
to several CICS regions.
- CICS Web
support and the business application can execute in the same CICS region.
- CICS Web
support can execute in a router region, and the business application can execute
in one or more application-owning regions (AORs). However, you cannot use
the EXEC CICS WEB API in the AOR, so a Web-aware application
program cannot execute in the AOR. You can use the EXEC CICS DOCUMENT
API in the AOR, but you must provide your own mechanism for transferring the
HTML output back to the router region. See Routing a Web client's request to an AOR for
more information.
Figure 1 illustrates these configurations.
Figure 1. CICS Web support configurations in a CICSPlex
You can distribute requests that use the CICS business logic interface in the same
way. This is illustrated in
Figure 2.
Figure 2. CICS business logic interface configurations in a CICSPlex
When
you plan to distribute applications in this way, you should consider any affinities
that exist between the parts of your application. For
more information about affinities, see the
CICS Interdependency
Analyzer for z/OS® User's
Guide and Reference
.
You should also consider how the application's state will be managed between
requests.
Managing application state across an HTTP request sequence discusses
the considerations involved for any CICS Web support applications which use
a pseudoconversational model. There may be additional considerations when:
- Dynamic routing is used to select the AOR within which the business application
executes.
- Workload and connection balancing is used to select the router region
(and, indirectly, the AOR).
CICS provides a sample state management program (DFH$WBSR) that you can
use to manage your application state. DFH$WBSR facilitates the sharing of
application state through resources that can be shared by several CICS regions.
It is described in
Reference information for DFH$WBST and DFH$WBSR, state management samples. (The other sample,
DFH$WBST, creates an affinity, and so is not suitable for use in a CICSPlex.)
For guidance about configuring CICS Web support and the CICS business
logic interface in a CICSPlex, see Workload Management for Web
Access to CICS.