External interfaces for initiating transactions

CICS provides a number of interfaces for submitting transaction requests to a CICS region from outside the CICS environment.

CICS Transaction Gateway

The CICS Transaction Gateway is a product that enables you to run programs in CICS from a Java application, using the Java Platform, Enterprise Edition (Java EE) interfaces.

CICS clients

A CICS client is a member of the family of CICS workstation products that provide a standard set of functions for client/server computing. CICS clients can initiate transactions in CICS using the external call interface (ECI) or the external presentation interface (EPI):

• The ECI is an application programming interface that allows a program in a client to call a CICS program. The client program can exchange data with the CICS program in a communication area (COMMAREA).
• The EPI is an application programming interface that allows a program in a client to simulate a 3270 terminal. The client program can interact with the CICS program in the same way as a terminal operator.

The CICS-MQ bridge

WebSphere MQ applications can use the CICS-MQ bridge to initiate a CICS transaction to process a message. A WebSphere MQ application can use synchronous or asynchronous processing. In synchronous processing, the WebSphere MQ application waits for the response from each CICS program before invoking the next one; in asynchronous processing, the WebSphere MQ application does not wait.

Using the CICS-MQ bridge, the WebSphere MQ application can exchange data with the CICS program in a communication area (COMMAREA), or simulate a 3270 terminal.

The TCP/IP Socket Interface for CICS

The TCP/IP Socket Interface for CICS is provided as part of the z/OS Communications Server element of z/OS. It supports peer-to-peer communication between CICS programs and other applications that use TCP/IP protocols.

The External CICS Interface (EXCI)

A z/OS program can use the External CICS Interface (EXCI) to invoke a CICS program using distributed program link (DPL).