Open System Services Programmer's Guide

9 Using Subsystems From OSS
There are HP subsystems that you can access from OSS programs. This section summarizes
considerations or limitations in using HP subsystems from your OSS application programs. The
section also provides references to manuals that discuss these subsystems in detail.
The following subsections discuss programmatic access from an OSS application to the
corresponding subsystems:
• “Communications Subsystems” (page 245)
• “Subsystems Supporting the Subsystem Programmatic Interface (SPI)” (page 245)
• “HP NonStop SQL/MP” (page 246)
• “HP NonStop SQL/MX” (page 246)
• “HP NonStop TS/MP” (page 247)
• “HP NonStop TMF” (page 247)
• “HP NonStop Tuxedo System” (page 247)
• “HP NonStop Distributed Computing Environment (DCE)” (page 248)
• “Simple Network Management Protocol (SNMP)” (page 248)
Communications Subsystems
A communications subsystem provides users with access to a set of communications services. It
consists of one or more processes running on a system and possibly a protocol module running
on a communications controller.
Examples of HP communications subsystems include Transmission Control Protocol/Internet Protocol
(TCP/IP), HP Tandem LAN Access Method (TLAM), X.25 Access Method (X25AM), SNAX Extended
Facility (SNAX/XF), Open Systems Interconnection/Application Services (OSI/AS), and Open
Systems Interconnection/Message Handling System (OSI/MHS).
You can access HP communications subsystems from OSS applications, but for some operations
you must use Guardian I/O procedures. You will probably want to use nowait I/O, which allows
a program to continue executing in parallel with read or write operations. Nowait I/O is not
available using OSS I/O functions. You also need to read the $RECEIVE file if the subsystem sends
status messages to $RECEIVE. Reading the $RECEIVE file requires using Guardian procedures.
Because you have to use Guardian procedures for significant portions of your program, it is easier
if you use Guardian I/O procedures exclusively to access communications subsystems instead of
mixing Guardian I/O procedures and OSS I/O functions.
For more information about HP communications subsystems, see the manual sets that describe the
subsystems you need to access. These manual sets can include introductory, configuration,
programming, and reference manuals.
Subsystems Supporting the Subsystem Programmatic Interface (SPI)
The Subsystem Programmatic Interface (SPI) provides a common interface for the management of
HP subsystems by site-written applications. SPI provides the path for management applications to
exchange command-specific messages and event messages with most subsystems and with many
modules of the Subsystem Control Facility (SCF).
SPI is available to C and COBOL programs. The primary requirement is to include the definitions
found in the appropriate Guardian environment header file (in the case of C programs,
$SYSTEM.ZSPIDEF.ZSPIC) when compiling the application. This requirement can be met by creating
a copy of the needed file in the OSS file system and including a reference to the file in the form
Communications Subsystems 245