TCP/IP Tutorial and Technical Overview - IBM Redbooks

2. The server uses the S-Connect.res response primitive to acknowledge
reception of the indication primitive. The client’s session layer uses the
confirm primitive to report that the activity (S-Connect.req) has been
completed successfully.
3. During the session initiation process, the client’s session layer can start
immediately with sending S-MethodInvoke.req requests asking for an
execution on the server’s machine. This request indicates that the upper layer
has to execute an operation on the server’s side.
4. The server sends a S-MethodInvoke.res response to the client confirming that
the previous S-MethodInvoke.req request was completed successfully. The
client is informed through S-Method.cnf.
5. After the server executes the operation, it sends the result to the client
through S-MethodResult.req. The client indicates the upper layer (the
application layer) through S-Method.Result.ind the receipt of the returned
data.
6. Because the session partners have negotiated confirmation of all requests
(***.req), the client confirms the S-MethodResult.req request with an
S-MethodResult.res. response.
7. Further requests and responses can use this session.
8. The active session can by terminated in this example by issuing a
S-Disconnect.req request to the server through the client. The server sends a
S-Diconnect.ind to the session services in the session layer, which finishes
the session. Session services on the client side will be informed to take down
the session through S-Diconnect.ind.
Because the session layer does not provide any sequencing between multiple
overlapping method invocations, the indications might be delivered in a different
order than the sent request. The same is valid also for responses and
confirmations, as well as for the corresponding S-MethodResult primitives. The
application has to handle the sequencing.
There are some other session service primitives that are not used in the samples
of the WSP connection-mode. These are:
S-Suspend Suspends a session.
S-Resume Resumes a session that was suspended.
S-Exception Reports events.
S-MethodAbort Aborts an operation request that is not yet complete.
S-Push Sends unsolicited information from the server.
S-ConfirmedPush Sends unsolicited information from the server; however,
the client has to confirm this information.
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