HP-UX SNAplus2 R7 Upgrade Guide (September 2005)

Porting Application Programs
Overview of Porting Applications
Chapter 320
Overview of Porting Applications
The SNAplus2 API libraries have been designed to be
backward-compatible, and to include all the functions that were
available in the back-level software as well as new functions specific to
the current-level software. When upgrading from Release 6 to Release 7,
you can run existing applications without any change to the application.
However, if you want to add a new function, for example adding the TP
Server for APPC, you must extend the application and relink the
program.
In some cases, the current-level API implements new functions using
VCB fields that were marked as “reserved” in the back-level API. If your
application sets all reserved fields to 0, as recommended, it will operate
with the new libraries with no change in function; however,
unpredictable results may occur if reserved fields are not set to zero.
If you are not modifying the application's source code, no action is
necessary; the application can run unchanged with the new shared
libraries.