Introduction to the 3270 bridge
The 3270 bridge provides an interface so that you can run 3270-based CICS® transactions without a 3270 terminal. The 3270 terminal and end-user are replaced by an application program, known as the client application.
Commands for the 3270 terminal in the CICS 3270 user transaction are intercepted by CICS and replaced by a messaging mechanism that provides a bridge between the client application and the CICS user transaction.
CICS provides two types
of 3270 bridge mechanism:
- The Link3270 mechanism
- This mechanism provides a simplified interface using LINK, ECI or EXCI. All messages have a fixed format and you are not required to provide any user-written supporting programs. This mechanism supports CICSPlex® SM load balancing; bridge facilities are shared between CICS regions on the CICSplex
- The START BREXIT mechanism
- This 3270 bridge mechanism requires a bridge monitor transaction to initiate the bridge environment by issuing a START BREXIT command, which specifies the target user transaction and also the name of a user-written bridge exit. The bridge exit is called to intercept 3270 requests and pass them in the form of messages to the client application. You can write your own bridge exit and also define your own message formats. Bridge exits are provided to support client applications using Temporary Storage, the Web and IBM® MQ as transport mechanisms for requests, using sample message formats. This mechanism is single region only: bridge facilities are local to the region.