HP 3000 Manuals HP 3000 Manuals
Introducing a New Open Systems Environment
MPE/iX Releases 4.5 and 5.0 introduce open systems environment features
that greatly enhance the flexibility of the MPE operating system with
which you are already familiar. The MPE/iX enhancements implement
features of POSIX, the IEEE operating system interface standard.
One of the primary advantages of MPE/iX is that the added flexibility is
optional--you can use the system essentially as you always have, or you
can use the enhanced features of MPE/iX. MPE/iX Release 5.0 is fully
backwards and forward compatible with earlier versions of MPE.
What's POSIX?
POSIX is an acronym for Portable Operating System Interface. The POSIX
standard, IEEE Std 1003.1-1990, is an international standard that defines
common interfaces as a basis for open systems. IEEE POSIX 1003 is
actually a group of standards, each of which addresses a specific area of
system technology. The POSIX standards describe functions of an
operating system interface that applications must use if they are to be
"POSIX compliant." Systems that implement the standard functions are said
to be POSIX compliant.
Initially, MPE/iX is implementing two of the standards to maximize the
software portability of applications: C language application programming
interfaces (also called POSIX.1) and a command interpreter (shell) and
utilities (called POSIX.2).
The main reason for implementing POSIX.1 functions on a system is to
increase software portability and minimize porting costs. Since POSIX.1
is based on Berkeley Software Distribution and AT&T's System V Interface
Definition, UNIX applications can be ported more easily to HP 3000
computer systems. Applications developed on any POSIX-compliant system
using POSIX.1 functions can be ported to other POSIX-compliant systems
and run with little or no modification.
The initial implementation of POSIX.1 makes MPE/iX POSIX compatible.
That is, it supports most of the key POSIX features including the
hierarchical directory structure, long file names, and process signals.
(Signals notify processes of events that occur on the system, such as
hardware exceptions.)
POSIX.1 defines procedural interfaces for C programs to high-level, basic
operating system services. These services include creating and purging
directories and files; creating, controlling, and terminating processes;
interprocess communications (for example, signals); byte- stream files;
user identification; grouping users for file sharing purposes; defining
and altering file security; grouping processes for signal sharing; and
changing a user's location within the file system.
How does POSIX change MPE/iX?
In implementing the 1003.1 and 1003.2 functions, HP has enhanced the
MPE/iX operating system. The main changes include
* Hierarchical file system (HFS)
* New file naming syntax (HFS syntax)
* Long file names
* Command enhancements
* Additional user environment (MPE/iX shell)
* Security enhancements (user identification ACD extensions)
* Byte-stream files (new record type)
* Symbolic links
* Enhanced process handling capabilities
These enhancements expand the current MPE file system structure. For
example, prior to Release 4.5 and 5.0, the file system allowed you to
create files under a group. As of Release 4.5 and 5.0, you can create
HFS directories, as well as files, under groups, or accounts.
MPE has traditionally imposed constraints on naming syntax. Names could
not exceed eight characters in length and could not contain special
characters. MPE/iX now provides an expanded naming syntax, called HFS
syntax, that allows for longer file names and has fewer constraints. HFS
syntax is available for use in addition to the traditional MPE syntax.
What does POSIX offer you?
MPE/iX enhancements enable you to do the following:
* Port applications written to POSIX.1 standards.
* Use HFS directories to create multilevel data hierarchies.
* Provide case-sensitive names greater than eight characters in
length.
* Rename and move files across account boundaries.
* Have a greater measure of control over files and directories on
the system.
When MPE/iX Release 4.5 and 5.0 is installed, you automatically have
access to POSIX functionality. No additional configuration is required
for you to use many of the POSIX features described in this document.
If you are a general user on MPE/iX, your activities need not change.
You can use the new features such as creating and using directories
within groups accessible to you.
If you are a programmer, standard programmatic and interactive interfaces
provide a standard development environment enabling source-sharing across
platforms. This development environment allows you to implement open
systems environment features.
If you are a system administrator, MPE/iX enables you to manage the
system basically the same as you have for MPE/V or MPE XL.
Programmers using the MPE/iX system may want to use the MPE/iX
Developer's Kit (36430A) to port open system applications onto MPE/iX. In
this case, system administrators need to be aware of programming
activities so that they can support them when managing the MPE/iX system.
Postponing the use of POSIX features
The introduction of POSIX features on MPE/iX places new demands on system
managers. Today, system managers have a full workload without extra time
to learn the new POSIX concepts. Chapter 3 discusses options available
to those of you who may wish to postpone using POSIX features.