CICS Transaction Gateway V5 The WebSphere ... - IBM Redbooks

1.2 CICS TG: Interfaces
All the principal interfaces provided by the CICS TG fall into one of three
categories, based on the function being invoked in CICS:
► External Call Interface (ECI)
► External Presentation Interface (EPI)
► External Security Interface (ESI)
For further details on programming with the CICS TG, refer to the redbook Java
Connectors for CICS, SG24-6401.
1.2.1 External Call Interface
The ECI is used for calling COMMAREA-based CICS programs. The
COMMAREA is the buffer that is used for passing the data between the client
and the CICS server. CICS sees the client request as just another distributed
program link (DPL) request (Figure 1-6).
CICS Transaction
Gateway
Figure 1-6 External Call Interface
ECI
LINK
CICS region
CICS
Application
An ECI request can be made in Java using one of three different interfaces:
► The ECIRequest class provided by the CICS TG base classes.
This provides a simple procedural type interface to the ECI, and it is used for
calling COMMAREA-based CICS applications.
► The Common Connector Framework (CCF) classes.
These classes implement the CCF interfaces and programming model. The
CCF is comprised of three core components: the CCF classes, the Enterprise
Access Builder, and the Java Record Framework.
► The Common Client Interface (CCI) provided by the J2EE Connector
Architecture.
These classes define a standard architecture for connecting the Java 2
Platform Enterprise Edition (J2EE) platform to a heterogeneous EIS such as
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Chapter 1. CICS Transaction Gateway 11