A Conversation
between Two TPs shows a conversation between two TPs as it
occurs over a session.
Figure 1. A Conversation
between Two TPs
A session can support only one conversation at a time, but one
session can support many conversations in sequence. Because multiple
conversations can reuse sessions, a session is a long-lived connection
compared to a conversation. When a program allocates a conversation
and all applicable sessions are in use, the LU puts the incoming Attach
(allocation request) on a queue. It completes the allocation when
a session becomes available.
Two LUs can also establish parallel sessions with each other to
support multiple concurrent conversations. A parallel session occurs
when either TP allocates a conversation, and a session exists but
is being used by a conversation. The LU can request a new session
to satisfy the allocation.
