TRANSFER Programming Manual

Initiating a Session
Designing and Writing a Client
069138, Update 1 to 040970 Tandem Computers Incorporated 9–3
Figure 9-1. Elements of a Session
TCP TISERV
Depot
Agent
Depot
TRANSFER Asynchronous Process
010
Because session IDs are unique in the network and TRANSFER servers are context
free, the following relationships can exist among requesters, servers, correspondents,
and sessions:
One requester can maintain sessions in progress for several correspondents.
Requests for each correspondent carry that correspondent's session ID.
The same requester can have more than one session for the same correspondent,
with different session IDs. The same correspondent, for example, might be a user
logged on at two terminals controlled by the same TCP.
Multiple requesters can maintain sessions in progress for the same correspondent
at the same time. Each requester has its own session ID for the correspondent.
The requests issued during a session need not all go to the same server, nor even
to the same server class. The session ID accompanies every TRANSFER request,
and any TRANSFER server at the node can interpret it correctly.