OSI/AS Programming Manual

What Is the API?
Introduction
1–4 056783 Tandem Computers Incorporated
The OSI Manager Process The OSI manager process manages the OSI/AS configuration information necessary to
set up OSI/AS connections. Each OSI/AS subsystem has exactly one OSI manager
process.
The OSI manager process provides management functions for TAPS processes. It also
provides some management functions for the TSP processes and very limited
management functions for the NSP processes. Most management functions for the
TSP and NSP processes must be performed through the management interfaces to the
OSI/TS, X25AM, and TLAM subsystems.
Management Information
Base (MIB)
The Management Information Base (MIB) is a key-sequenced file that contains
management information for the OSI/AS subsystem. It serves as a database
containing, for example, the OSI address of your application and the OSI addresses
needed to make a connection to a remote application. Each OSI/AS system has one
(and only one) MIB. You configure the MIB using one of two interfaces:
The interactive Subsystem Control Facility (SCF) interface, described in the Tandem
OSI/AS Configuration and Management Manual and the SCF Reference Manual for
Tandem OSI/AS
The DSM programmatic interface, described in the Tandem OSI/AS Management
Programming Manual
The OSI Layers Tandem OSI/AS and its underlying subsystems cover the following parts of the OSI
Reference Model:
The lower layers (Layers 1 through 4)
The Session Layer
The Presentation Layer
The Association Control Service Element (ACSE) in the Application Layer
For a description of the OSI Reference Model, refer to ISO 7498.
The Lower Layers
OSI Layers 1 through 3—the Physical, Data Link, and Network Layers—are
responsible for the physical transfer of data and network routing between OSI
systems. Layer 4, the Transport Layer, provides reliable, cost-effective transfer of data
between entities. These tasks are performed for OSI/AS by underlying Tandem
subsystems.
The Network Layer functions are provided by NSP (network service provider)
processes. NSP processes are supplied by one of the following underlying Tandem
subsystems:
The X.25 Access Method (X25AM), for wide area networks
The Tandem LAN Access Method (TLAM), for local area networks
NSP processes actually provide more than just Network Layer functionality. For wide
area networks, X25AM provides the functions of the Physical Layer, the Data Link