Open System Services Porting Guide (G06.24+, H06.03+)

Interoperating Between Programming Environments
Open System Services Porting Guide—520573-006
5-2
Major Differences Between Programming
Environments
Major Differences Between Programming Environments
When using Guardian procedures in the OSS environment, you need to realize that the
characteristics of the Guardian environment are different from those of the OSS
environment:
•
Guardian processes are identified by their process handles; OSS processes are
identified by their process IDs and process handles. Guardian processes do not
have OSS process IDs.
•
Guardian startup messages are used to pass information from a ancestor process
to the created process when a Guardian process is created. In the OSS
environment, the propagation of shared memory and open files conforms to the
UNIX model: an OSS process inherits the open file descriptors of its parent and
parameters from arguments put in its data resource at startup time.
•
The relationship between MOM and ancestor processes is indicated differently for
Guardian processes than it is for OSS parent and child processes. These
differences can create complications when a Guardian process-creation function is
called from the OSS environment. For more information on OSS and Guardian
process attributes, refer to the fork(2) reference page either online or in the
Open System Services System Calls Reference Manual, and to the
PROCESS_LAUNCH_ procedure in the Guardian Procedure Calls Reference
Manual.
•
The standard text files in the Guardian environment are EDIT files; the standard
text files in the OSS environment are unstructured ASCII files.
•
File naming conventions in the Guardian environment are more restricted than they
are in the OSS environment.
Terminals in the OSS environment are accessed through a TELNET/Telserv
application. OSS also supports local terminals through OSSTTY, although OSSTTY
has the look and feel of a remote terminal. All print spooling is done through the
Guardian spooler. Yet, the normal UNIX lp commands can be used from OSS. See I/O
Interoperability on page 5-12.
Table 5-1 lists additional differences between the OSS and Guardian environments.
The Open System Services Programmer’s Guide contains extensive discussions on
the differences between the two file systems, the two process types, and managing I/O
between environments. The Open System Services User’s Guide contains extensive
discussions on the two command interfaces, creating files, and managing the different
file systems.