OSI/AS Management Programming Manual

OSI/AS Subsystem Architecture
Introduction
1–2 056785 Tandem Computers Incorporated
Information obtained through programmatic interfaces can be translated directly
into procedures, reports, and so forth.
An application that uses the programmatic interfaces to subsystems can perform tasks
that once required the use of several different interactive interfaces. In addition, the
capability to write your own management applications allows you to tailor them to the
needs and configuration of your network.
You could, for example, write a management application that obtains statistics on
Application Layer traffic and compares them to other statistics, counting the total
number of transactions. This comparison could determine what percentage of the total
transaction load represents network transactions.
Your applications can communicate with other subsystems as well as with the OSI/AS
subsystem. For instance, an application that communicates with OSI/AS may also
need to communicate with OSI/TS, X25AM, and/or TLAM. In order to find out the
status of the lower layers of a specific connection, an application might first issue a
STATUS SU command to OSI/AS. From the response, the application can obtain the
name of the OSI/TS subdevice (SU). From the response to a STATUS SU command to
OSI/TS for that subdevice, the application can get the name of the TLAM port or the
X25AM subdevice. Then the application can obtain further lower-layer information
about the subdevice.
OSI/AS Subsystem
Architecture
The OSI/AS subsystem provides a Session Layer, Presentation Layer, and Association
Control Service Element (ACSE) interface to OSI networks. Figure 1-1 shows the
relationships among the various components of the OSI/AS subsystem and a
communications application that uses OSI/AS.
The OSI/AS subsystem itself provides two kinds of processes:
The OSI manager process, which manages the information necessary to set up
connections—for instance, configuration attributes for the various OSI layers
The Tandem application, presentation, and session (TAPS) processes, which
service currently active connections
Services below the Session Layer are performed by the following processes provided
by underlying Tandem subsystems:
One or more transport service provider (TSP) processes, which implement services
and protocols of the Transport Layer and of the internet protocol (IP) of the
Network Layer
One or more NSP (network service provider) processes, which implement other
services and protocols of the Network Layer and, for local area networks, some
functions of the Data Link Layer
The Tandem OSI/TS software provides the TSP processes. NSP processes are
provided by X25AM for wide area networks, or by TLAM for local area networks.