Sun Microsystems SunLink SNA 9.1 PU2.1, Configuration Manual

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SNA Concepts C-13
C
C.5.2 Conversations and Verbs
TPs always communicate in pairs. A logical connection called a conversation is
established between the two TPs. Conversations make temporary use of
sessions set up between the TPs' respective LUs. Programs communicate on
conversations using the verbs defined on the conversation protocol boundary
between the TP and its local LUType 6.2. Mapped and basic conversation types
are supported.
A conversation is initiated by the invoking TP, which issues an Attach verb.
The local LUType 6.2 attaches a session (provided one is available or can be
activated) to the conversation and issues an Attach request on the session. The
partner LUType 6.2 receives the Attach request, and provided the request is
valid, invokes the remote TP.
You can specify the following parameters for a conversation:
•
The conversation type(s) supported by the TP: mapped and/or basic.
•
The sync level(s) supported by the TP: none and/or confirm (and in special
circumstances, sync point).
•
The security required on the Attach request to run the TP.
•
The process command line to start the TP, if required. If a TP is not already
waiting to accept the Attach request, the server will, if a command line is
configured, auto-start the TP. Otherwise, the TP must be started manually.
•
An Attach time-out period to wait for the TP to accept the Attach request. If
the TP does not accept the Attach within this period, the server detaches the
conversation (
TP_NOT_AVAILABLE
).
C.5.3 Sessions and Modes
Sessions are the logical connections maintained between NAUs. LUType 6.2
sessions are attached to one conversation at a time. Since establishing and
removing LUType 6.2 sessions involve significant processing, a session is
usually left up when a conversation terminates so that the session can be made
available to the next conversation.
The characteristics of a session between a local LUType 6.2 and a remote
LUType 6.2 (or LU-LU pair) are specified with a mode. The mode defines
various communications and usage parameters, including the following:
•
The preferred size of the Request/Response Units (RUs) to be exchanged by
the two LUType 6.2s.