7.1.1 Implicit API

The implicit API can be a useful simplification for many applications. While it does not provide all the existing LU6.2 capabilities, this API provides additional functions, such as message queueing and automatic asynchronous message delivery.

Using the IMS application programming base with the implicit API, you can write transactional applications that do not have Common Programming Interface for Communications (CPI-C) calls. IMS generates all the CPI-C calls for you. The application interaction is strictly with the IMS message queue.

The implicit API accesses an APPC conversation indirectly. It uses the standard DL/I calls (GU, ISRT, PURG) to send and receive data. The implicit API allows non-LU 6.2 specific applications to use LU 6.2 transactional protocols, using new and changed DL/I calls (CHNG, INQY, SETO).

The implicit API creates asynchronous LU 6.2 output by using alternate PCBs referencing LU 6.2 destinations. The DL/I CHNG call can supply parameters to specify an LU 6.2 destination. Default values substitute for omitted parameters.

An application program can use the implicit API to retrieve the current conversation attributes, such as the conversation type (basic or mapped), the sync_level, and whether it is asynchronous or synchronous.