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

12 CICS Transaction Gateway V5
CICS. Java applications interact with resource adapters using the Common
Client Interface (CCI), which is largely based on the CCF, but it is a standard
that is open to the entire Java community.
1.2.2 External Presentation Interface
The EPI is used for invoking 3270-based transactions. A terminal is installed in
CICS, and CICS sees the request as running on a remote terminal controlled by
the CICS TG. For further details on programming with the EPI, refer to Chapter 7,
“EPI support classes”, in the redbook Java Connectors for CICS, SG24-6401.
CICS
Transaction
Gateway
EPI
Figure 1-7 External Presentation Interface
CICS region
3270
presentation
logic
CICS
Application
An EPI request can be made in Java using one of five different interfaces:
► The EPIRequest class provided by the CICS TG base classes.
This class provides a Java interface to the EPI, and is used for invoking
3270-based transactions. Due to its low-level nature, using it for developing
EPI applications requires a strong knowledge of CICS and 3270 data
streams.
► The EPI support classes, which provide high-level constructs for handling
3270 data streams.
A wide range of classes is provided including AID, FieldData, Screen,
Terminal, Map and MapData. These are used to represent the interface to a
CICS 3270 terminal, and the resulting 3270 response.
► The EPI beans, which are based on the EPI support classes and JavaBean
development environment.
They allow you to create EPI applications in a visual development
environment, using one of the visual application builder tools, such as
VisualAge® for Java.