GDSX (Extended General Device Support) Manual

Extended General Device Support (GDSX) Manual—529931-001
2-1
2 Design and Development
This section contains design prerequisites and considerations for designing GDSX
applications; information on D-series features; steps for converting applications to use
extended features of the D-series operating system; considerations for coding,
compiling, and binding GDSX procedures; a description of the basic internal control
flow; procedure call and space restrictions; and information on memory pools, fault
tolerance, semaphores, linked lists, EMS filters, file-system errors, tracing, GDSX
internals, and the USAMPLE example program.
Prerequisites for Design and Development
A programmer developing a GDSX application must:
•
Be an expert TAL programmer
•
Know the requirements for the application to be developed
•
Know HP architecture and NonStop operating system programming
•
Be familiar with multithreaded processes
•
Be familiar with fault-tolerance principles, if the application is to run as a process
pair
•
Know data communications, if the application is to include protocol conversion
Before you begin designing a GDSX application, you should read Section 2, Design
and Development and do the tutorial in Section 4, DEVICE^HANDLER Example,
Running and Managing through Section 7, LINE^HANDLER Example, Design, unless
you are already proficient in GDSX programming. (If your application does not involve
a LINE^HANDLER, you do not need to do Section 6, LINE^HANDLER Example,
Running and Managing and Section 7, LINE^HANDLER Example, Design of the
tutorial.)
Finally, before designing a GDSX application, it is recommended that you consider
alternative implementations, such as Pathway/iTS IDS or conversational mode. See
When to Use GDSX on page 1-16.
Design Considerations
The following considerations and suggestions may be helpful when designing a GDSX
application.
•
Determine the environment in which GDSX is to function. Chart the overall
interprocess data flow. Include the interprocess flow of data from external
business application to GDSX to IOP/other process. Diagram the GDSX internal
data flow.