OSI/FTAM Programming Reference Manual

Introduction to NonStop OSI/FTAM
HP NonStop OSI/FTAM Programming Reference Manual—528611-001
1-5
Architectural Overview
Tandem LAN access method (TLAM) or the X.25 access method (X25AM) to
communicate with remote computer systems across a network.
NonStop FTAM, the OSI/AS subsystem, the OSI/TS subsystem, and TLAM or X25AM
must be configured and running on the NonStop system for your application to
communicate with a remote system. For more information about OSI/AS, OSI/TS,
TLAM, and X25AM, see Figure 1-6 on page 1-13 and the accompanying text.
The OSI/FTAM Programming Guide provides more information on system
configuration requirements for running applications using FTAM. For details on
NonStop FTAM configuration and the services underlying NonStop FTAM, refer to the
OSI/FTAM Configuration and Management Manual.
Architectural Overview
FTAM services facilitate communication between different computer systems on an
OSI network. The communication link (at the FTAM level) created between two
systems is called an association. Each system is further defined in terms of its function
in the association. The system that creates and controls the association is called the
initiating system. The system that responds to the initiating system is called the
responding system. In NonStop FTAM, the initiating and responding functions are
performed by two processes: the initiator process and the responder process.
The initiator allows NonStop FTAM applications to access FTAM protocol and request
services of a remote responder. The NonStop FTAM application programmatic
interface (API) is a set of procedures that interact with the initiator process. An
application uses these procedures to perform FTAM services, such as accessing files
on a remote computer system that supports FTAM.
The NonStop FTAM responder services FTAM requests initiated from remote systems
on the network. The responder acts as an FTAM file server, mapping FTAM requests
into Guardian file operations and providing a translation between Guardian file
structures and FTAM file structures. The responder has no programmatic interface.
Figure 1-2 on page 1-6 provides an overview of the NonStop FTAM architecture.
NonStop FTAM provides two user interfaces:
•
NonStop FTAM application programmatic interface (API), which is the interface
between the FTAM application and the initiator. For details on the NonStop FTAM
API, refer to Section 3, NonStop FTAM Initiator.
•
Distributed Systems Management (DSM) interactive interface, which is used to
configure and control NonStop initiator, responder, and APLMGR processes. For a
Note. The term “association” denotes a communication link between entities of the Application
Layer of the OSI Reference Model (specifically the Association Control Service Element, or
ACSE), and a “connection” is a communication link between entities of the six OSI layers below
the Application Layer. Because this manual focuses primarily on associations at the Application
Layer, it seldom uses the term “connection,” used extensively in the OSI/AS Programming
Manual.