Developing with CICS business logic interface

The CICS® business logic interface makes it possible to link to a web-aware business application, rather than invoking it through the CICS HTTP listener. For example, a web server running on z/OS® can use the external CICS interface (EXCI) to link to an application using the CICS business logic interface. In this way, a web client can communicate with a CICS application through an intermediate web server, rather than making a direct connection to CICS.

How can you use the CICS business logic interface

You can call the CICS business logic interface in any environment where you can link to a CICS application program.

  • You can issue an EXEC CICS LINK command from a CICS application program.
  • You can use the external CICS interface (EXCI).
  • You can use the external call interface (ECI) from a client.
  • You can use CICS ONC RPC support from an ONC RPC client.

See CICS business logic interface: Processing examples to learn about how the CICS business logic interface processes a request from a z/OS application that uses either the EXCI or the ECI.

The CICS business logic interface can be called in two modes: offset mode and pointer mode. When you call the CICS business logic interface, you must specify the mode. See Offset mode and pointer mode for details.

To make decisions about what facilities you will use and how you will customize them, you need to understand how the components of the CICS business logic interface interact and how data is passed in the interface. See Control flow in request processing and Data flow in request processing for information.

For reference information about the CICS business logic interface, see CICS business logic interface, DFHWBBLI.

How should you handle code page conversion

The CICS business logic interface does not perform code page conversion; the data that you pass to the business application, and the data that is returned is in the code page used by the application programming interface.

However, the EXEC CICS WEB application programming commands allow you to specify the client code page, and the data is converted in the application programming interface itself. Therefore, when you use these commands, code page conversion is performed between the application program and the CICS business logic interface. The data passed across the interface is in the code page specified in the CHARACTERSET option of the EXEC CICS WEB commands (or its synonym CLNTCODEPAGE).

What system configuration and resource definitions are required

  • You must set the WEBDELAY system initialization parameter, as described in Specifying system initialization parameters for CICS(r) web support .
  • If you are not using autoinstall for programs, you must define all the user-replaceable programs (converters) that the callers of the CICS business logic interface use. If you are using autoinstall for programs, you do not need to define the converters. All the converters must be local to the system in which the CICS business logic interface is operating.