The last segment in a message (either sent by the client, or received
from the server) is indicated by an end-of-message (EOM) segment.
(See End-of-message segment (EOM)).
- Implicit-mode messages sent by the client are received by the
Listener. When the client program sends an EOM segment, the Listener
interprets the EOM as an indication that no more message segments
are to be received and inserts the segments onto the IMS™ message queue.
- Implicit-mode messages received by the client are actually written
by the Assist module on behalf of the server program. When the server
program sends application data to the client (using the ISRT call),
the Assist module intercepts the output data and accumulates it in
an output buffer. When the server program issues a subsequent GU to
the I/O PCB, the Assist module interprets the GU as an indication
that the server has inserted the last segment for that message. The
Assist module then adds an end-of-message segment to the output data
and issues WRITE commands, which transmit the data to the client.
(The client program should test for the EOM segment to determine when
the last segment of the message has been sent by the server program.)