CICS Application Programming:
Client/Server and other Advanced Functions & Facilities

Transaction Flow

Following a standard CICS pseudoconversational transaction on its way though CICS we will discuss the various CICS management modules involved, the required resource definitions, and the general functions and facilities provided by these modules.

Program Management

Invoking one program from another - that is the topic for this section. The differences between CALL and LINK will be discusses as well as the usage of XCTL versus LINK. We will present some techniques for avoiding I/Os and on saving virtual storage.

Front End Processing

The front end processing section starts out with a discussion of BMS. The options and facilities provided by BMS are explained and recommendations are given on which of these facilities the programmer should avoid. We will look at related features like FEPI and the EPI Interfaces which allow new GUIs for old "legacy" applications.

Distributed Programming - Using Intersystem Communication Facilities

The various members of the CICS family can coexist, and communicate with each other. The CICS facilities provided by Transaction Routing and Function Request Shipping will be explained. Usage of these facilities in programming techniques like DTP (Distributed Transaction Processing) or ATP (Asynchronous Transaction Processing) will be discussed and guidelines given on when to use a facility, or when to replace it by a more suited mechanism. After discussing the principles of APPC based application programming we will introduce the distributed programming link facility

BTS Containers, and Channels

Since CICS Commadn level programming is available the COMMAREA has been the interface vehicle of choice between various CICS processes. With the amount of data that needs to be communicated between modules ever grwong, and transactions (especially those utilizing the web) can take much longer than the classical "green screen" CICS transactions new mechanism for data communications had to be developed. Those newer functions include Business Transaction Services (BTS) for lon-running transactions, and channele for nearly unlimited data transfer between application modules in CICS

EXCI - External Call Interface

So far we have talked about CICS to CICS communication from an application viewpoint. This topic discusses the techniques for batch programs to communicate with CICS applications via the EXternal Call Interface, which allows a batch program to invoke a CICS application via the standard EXEC CICS LINK mechanism

3270 Bridge

There a many programs around that utilize the 'classical' CICS interface via a 3270 type terminal. the 3270 Bridge technique allows to bring those programs into the www without any code changes, and with minimal changes to the BMS/3270 maps utilized by the application

CWI - CICS Web Interface

Of course CICS does not only support 3270 type applications for the Web. CICS can directly make use of the www by providing API commands that allow running a CICS application under a web browser, making CICS somewthing like a web server.

CWS - CICS Web Support

The latest in CICS / Web enablement is CICS Web Support which allows CICS to act not only as a web server (thus providing information to a requestor/client), but also as a web client (thus allowing a CICS application to request information from some other web server). This includes support for the SOAP protocol

CICS Application Programming: Client/Server and other Advanced Functions & Facilities