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

4.1 Introduction to EXCI
66 CICS Transaction Gateway V5
The EXCI provides a means for non-CICS address spaces on z/OS to link to
programs in a CICS region. For example, the EXCI allows batch jobs to connect
to CICS and also allows the CICS Transaction Gateway for z/OS to make calls to
CICS (Figure 4-1).
CICS
Transaction
Gateway
EXCI
MRO/IRC
EXCI pipes
Figure 4-1 CICS client-server connections
MRO
connection
z/OS
CICS TS
region
On z/OS the use of the EXCI limits the CICS TG to the subset of the ECI that the
EXCI supports, and prevents use of the EPI to invoke 3270-based transactions,
or the ESI to invoke password expiration management (PEM) functions in CICS.
For further details on the different interfaces (ECI, EPI, ESI) provided by the
CICS TG, refer to 1.2, “CICS TG: Interfaces” on page 11.
For all connected EXCI client systems, the CICS server region requires both a
CONNECTION and SESSIONS definition. The CONNECTION definition
identifies the remote system, and one or more SESSIONS definitions are
associated with this CONNECTION to define the properties of the sessions.
In the following sections, we provide further information on setting up EXCI on
z/OS. For more details, refer to the CICS External Interfaces Guide, SC33-1944.
The EXCI protocol is inextricably tied to the CICS Transaction Gateway for z/OS
and must be set up in tandem with the CICS TG for z/OS. For details on how we
configured the CICS Transaction Gateway for z/OS, refer to Chapter 7, “TCP
connections to the Gateway daemon on z/OS” on page 133.
For details on securing connections using the CICS Transaction Gateway, refer to
Chapter 6, “CICS TG security scenarios” on page 99.