Open System Services Programmer's Guide

1 Overview of the OSS Programming Environment
OSS is an alternative to the Guardian interface through which users and programs can interact
with the HP NonStop operating system. OSS interfaces and functions greatly resemble those of
UNIX systems in general, because of their common relationship to the POSIX standards. OSS adds
to the UNIX API by offering access to Guardian fundamentals and interoperability with the Guardian
environment by offering extensions to the standard API, additional OSS function calls, and access
to Guardian procedure calls.
OSS provides:
• A basis for middleware products. OSS supports a variety of middleware software, such as
the HP NonStop Tuxedo, NonStop Distributed Object Manager/MP (DOM), and NonStop
Server for Java products, that might also be used in an application.
• The Perl, PHP, and Python scripting languages.
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• An open interface to the operating system for supporting portable applications.
This guide focuses on the latter function: writing applications in C for the OSS target execution
environment without the use of middleware. For your convenience, Chapter 9: Using Subsystems
From OSS (page 245) contains a brief overview of some of the middleware available for NonStop
systems. For more information on such middleware, refer to the manual set for the specific software
product in which you are interested.
The OSS programming environment allows you to access Guardian objects and subsystems as
well as OSS objects. OSS accomplishes this interoperability between environments using standard
library and system function calls, and HP extensions to these calls and to Guardian procedures.
This section discusses the following topics:
ContentTopic
Relationship to the Guardian API and the NonStop
operating system, and conformance to industry standards.
“The OSS API” (page 27)
Basic differences between the OSS and Guardian file
systems, including directory structures, file access, and file
types.
“Two File Systems” (page 28)
Basic differences between the OSS and Guardian
processes, including process identifiers, groups, ancestors,
attributes, and pairs.
“Two Process Types” (page 32)
Typical source and target execution environments and
exceptions to the typical case.
“Selecting Source and Target Execution Environments”
(page 37)
How to call OSS functions and Guardian functions and
procedures and when to use them.
“Calling Functions and Procedures in OSS Programs”
(page 37)
Available editors, development utilities, compilers, linkers,
optimizers, debuggers, performance analyzers, and porting
kit.
“Using the Development Tools” (page 43)
An integrated development environment that enables you
to build applications on a PC.
“Using the HP Enterprise Toolkit - NonStop Edition”
(page 52)
1. For detailed information about these scripting languages in the OSS Script Languages (T1203) product, see the Script
Languages User Guide.
26 Overview of the OSS Programming Environment