Communications Method Calls

Communications method calls enable application programs to establish and revoke communications connections with servers and to establish unique communications contexts. A list of available servers may be obtained from the API, and one or more processing sessions may be set up with each server.

Reference: Communications Method Calls

Method	Description
EDACONNECT	Connects to the server and establishes a communications context.
EDAXCONNECT	Disconnects from the server and releases associated resources.
EDASERVERS	Retrieves a list of available servers from the connector. Capabilities of this call are improved by EDABROWSE.

Client/server relationships or communications contexts are represented by SCBs. One SCB corresponds to a server task by a single client/server communications thread, as illustrated in the following figure.

The next figure depicts multiple SCBs connected to multiple server subtasks by multiple client/server communications threads.

As shown in the above figure, there is a many-to-one relationship between SCBs and subtasks on a particular server. This default behavior of the API is called multiplexed. This multiplexed behavior enables the API to support multiple-independent communications contexts without unnecessarily increasing overhead on the server. The client can suppress multiplexed behavior by setting an EDASET variable. A user may also control multiplexing of SCBs to specific servers-called semiplexing. For information on multiplexing and semiplexing, see Advanced Usage Considerations.