2.2 CICS Transaction Gateway for OS/390

CICS Transaction Gateway provides a set of Java-based facilities to access CICS applications from a web browser. CICS Transaction Gateway for OS/390 Version 3.1 replaced the CICS Gateway for Java on OS/390, which was shipped as a component of CICS TS for OS/390 1.2. CICS Transaction Gateway is shipped with various products including CICS TS OS/390 1.3 and certain editions of WebSphere Application Server and VisualAge for Java. IBM claim that CICS Transaction Gateway for OS/390 offers better performance than CICS Gateway for Java (MVS).

CICS Transaction Gateway for Java provides the following

1. A Java gateway application

• communicates with CICS applications running in CICS servers through the External CICS Interface.

2. A CICS Java class library

• includes classes that provide an application programming interface
• used to communicate between the Java gateway application and a Java application (applet).
• The class JavaGateway is used to establish communication with the Gateway process, and uses Java’s sockets protocol.
• The class ECIRequest is used to specify the ECI calls that are flowed to the gateway.

For the External Call Interface, the information flows between the browser and CICS as follows:

1. The Browser downloads a page from the Web server.
2. When the browser finds an applet tag in a page, it fetches the applet from the Web server
3. The Browser executes the applet.
4. An applet that is going to communicate with CICS calls the CICS Transaction Gateway long running task.
5. The applet requests a CICS program
6. The CICS Transaction Gateway receives the request, and calls the CICS program.
7. When the CICS program ends, the results are returned to the Web browser.

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