Generic Listener Service

The generic listener service facilitates the implementation of concurrent servers quickly and easily. Generic listening performs the following tasks:

Creates a stream socket on a given port, optionally on a specific TCP/IP stack.
Listens on the socket.
Accepts connection requests, acquires a PTERM/LTERM pair and attaches a server task on it. This continues until the service is stopped.
Waits for input on the socket if a server task ends normally without closing its socket. This allows implementation of suspend/resume processing, which is useful when a client application wants to keep the connection alive without tying up a CA IDMS/DC task. Whenever the client application is ready to proceed, it sends another message over the connection. When the generic listener service receives this message it attaches a new server task on the same PTERM/LTERM pair. The task code that is invoked on a resume can be specified in the prior task by using the NEXT TASK clause of the DC RETURN statement. If the next task code is not set, the task code specified in the listener PTERM definition is invoked.