Guardian Application Conversion Guide

Conversion Considerations and the Common Run-Time Environment (CRE)
Conversion Concepts
096047 Tandem Computers Incorporated 2–19
The HIGHREQUESTERS
Attribute
The HIGHREQUESTERS attribute allows an unconverted server process to support
high-PIN requesters if the server meets certain requirements; that is, if the server does
not examine its openers. This attribute gives you the option of not converting the
server process, but you must be sure that the server process allows you to do this.
Appendix C, “System Compatibility,” provides additional information on the use of
the HIGHREQUESTERS attribute.
The RUNNAMED Attribute The RUNNAMED attribute causes a process to run as a named process even if the
creator does not provide a name. This attribute allows your process to run at a high
PIN and be opened by an unconverted process. Again, this option can work only if
the process does not examine its openers.
Conversion
Considerations and
the Common Run-Time
Environment (CRE)
The C-series C, COBOL85, FORTRAN, Pascal, and TAL programming languages each
have their own run-time environments defined by their respective run-time libraries.
These language-specific run-time environments are different from one another and are
often incompatible. Mixed-language programs running in these environments are
limited in their ability to use all of the features of each language and to share data
between routines written in different languages. This incompatibility severely limits
the potential for creating useful mixed-language programs.
The Common Run-Time Environment (CRE) eliminates this problem. The CRE
coordinates many run-time tasks on behalf of the run-time libraries, thus providing a
common environment for routines in a program, regardless of language. The CRE
provides services that significantly enhance your ability to create mixed-language
programs. These services include:
Shared access to standard files (standard input, standard output, standard log)
Shared access to a common run-time heap
Management of $RECEIVE
Management of process pairs
Uniform handling of exceptions
Uniform form and content of diagnostic messages
Routines in a program that runs in the CRE call language-specific run-time libraries as
in prior releases. However, these language-specific run-time libraries now call the
CRE library for some operations. Programs that run in the CRE can also make explicit
calls to CRE library routines. The CRE library replaces large portions of each
language’s run-time library; it does not replace Guardian procedures. The CRE allows
all routines in a program, regardless of language, to use their own run-time libraries as
well as CRE library routines and Guardian procedures.
All C-series compilers generate programs that run in a language-specific run-time
environment. The D-series C and Pascal compilers always generate programs that run
in the CRE. You can specify a compiler directive to instruct the D-series COBOL85,
FORTRAN, and TAL compilers to generate programs that run in the CRE.