Inbound communication with CICS applications

BeanConnect supports the communication protocol LU6.2 for inbound communication with a CICS application. To allow communication to take place by means of BeanConnect, some additional restrictions and rules apply:

• Basic conversation is not supported. Basic conversation is programmed for CICS using commands that begin with GDS.

• PIP data cannot be used for the CONNECT PROCESS call. The data is lost.

• It is not possible to use different mode names for different connections to the same partner. For CICS/ESA V4.1 the mode name is set in the session definition and can then be selected implicitly in the program interface using the SYSID parameter in the ALLOCATE call.

• If an LU6.2 conversation to the Java EE application server cannot be opened due to internal connectivity problems in BeanConnect itself, CICS does not receive a detailed rejection message. The detailed rejection messages can only be found in one of the protocol files of BeanConnect.

• BeanConnect supports SYNCLEVEL 0 (non-transactional conversation) and SYNCLEVEL 2 (transactional conversation).The SYNCLEVEL is set in CICS-API using the SYNCLEVEL parameter for CONNECT PROCESS.

• If inbound communication uses SYNCLEVEL 2, the CICS program must call the proxy for the end of the transaction with the commands SEND LAST and SYNCPOINT or ISSUE PREPARE. Then the proxy terminates the transaction. CICS can request the end of the transaction either when sending the user message or after receiving the answer.

• Only one-step dialogs are possible (one SEND INVITE call in the CICS program). However, message and reply may comprise several parts. A SEND and a RECEIVE call must be executed for each message part. The last part is indicated by the sender with a SEND INVITE call.

• With SYNCLEVEL 0, the OLTP message-driven bean terminates communication. This means that CICS may send a message using SEND INVITE and receive the corresponding reply message using RECEIVE. Subsequently, the dialog is terminated and SEND LAST is no longer permissible. However, it is possible for CICS to submit SEND LAST instead of submitting the SEND INVITE / RECEIVE pair. Here, CICS sends the message to the OLTP message-driven bean without receiving a corresponding reply message.

A CICS program for inbound communication must be designed and coded to comply with the Distributed Transaction Programming (DTP) paradigm. For a description of this programming paradigm, see the IBM CICS documentation, e.g. the CICS Distributed Transaction Programming Guide.