How the LANSA Composer Request Server for IBM i Works

LANSA Composer

How the LANSA Composer Request Server for IBM i Works

The diagram below provides an overview of the way the LANSA Composer Request Server for IBM i works for the case where a LANSA Composer Processing Sequence uses the CALL_FUNCTION activity to synchronously "call" a LANSA function that may be in a different LANSA system and/or partition.  The numbers in the diagram refer to the notes that follow.

Although this diagram illustrates the CALL_FUNCTION activity, the processing is similar for the reverse case where a LANSA application "calls" a LANSA Composer Processing Sequence using the COMPOSER_RUN built-in function.

1.  The activity processor for the CALL_FUNCTION activity posts the request to the request server by adding one or more entries to header and detail data queues used by the LANSA Composer Request Server.  It may also start the request server job automatically if it detects that there is not one available.

2.  The LANSA Composer Request Server receives details about the request from the data queues.

3.  For the CALL_FUNCTION case, the request server populates the exchange list in the target LANSA system with any exchanged variables and calls the specified LANSA function.  It then receives exchanged variable values from the LANSA exchange list.

4.  The request server posts any response data to the response data queue.

5.  The activity processor for the CALL_FUNCTION activity receives the response data from the data queue, determines the result and updates values in the Processing Sequence variable pool as necessary.