OSI/TS Configuration and Management Manual

Managing a Transport Connection
OSI/TS Configuration and Management Manual—424831-001
6-8
Application Manages the Response Protocol
users have to give OSI/TS permission to respond to incoming connection requests. This
permission is a file-system call that does not correspond exactly to any OSI transport
service primitive.
OSI/TS allows you to specify whether the subsystem or your application manages the
responder protocol. It is more convenient for the application if the OSI/TS subsystem
manages the responder protocol. The application, however, has to give up direct control
of the construction of the CC-TPDU. Since connection negotiation parameters are not
passed to the transport user, OSI/TS must determine whether the connection request is to
be accepted and what values for the negotiation parameters are to be returned.
The following subsections describe each option. See Section 7, NonStop Kernel File-
System Interface for a description of the procedure calls required to set up the responder
protocol.
Application Manages the Response Protocol
This option corresponds most closely to the abstract procedure described in the OSI
Reference Model. It requires two file-system calls—WRITEREAD, followed by
WRITE.
The following steps describe how the application manages the response protocol:
1. The write part of the WRITEREAD call gives the OSI/TS subsystem permission to
accept incoming TPDUs and tells the subsystem that the application is going to
handle the responder protocol. This requirement of the file system does not
correspond to any OSI transport service primitive.
2. When a CR-TPDU arrives, OSI/TS completes the WRITEREAD call and includes
the connection negotiation parameters that were delivered. This completion
corresponds to a T-CONNECT indication service primitive.
3. If the application accepts the connection request, it issues a WRITE call to OSI/TS.
This call contains connection negotiation response parameters that OSI/TS includes
in the CC-TPDU. This WRITE call corresponds to a T-CONNECT response
service primitive.
OSI/TS Manages the Response Protocol
For this option, OSI/TS uses configured values associated with a subdevice to negotiate
connection parameters and manage the responder protocol independently of the
application. This option requires only one call. It provides a convenient way for an
application to respond on frequently used connections.
The following steps describe how the OSI/TS subsystem manages the response protocol:
1. The application issues a CONTROL 11 call that gives OSI/TS permission to accept
and respond to valid CR-TPDUs. This call does not correspond to a transport
service primitive.
2. When OSI/TS receives a valid CR-TPDU, it responds with a CC-TPDU, setting
response fields for the connection parameters by applying negotiation algorithms to
configured subdevice values and CR-TPDU parameters.