HP NonStop G-Series - Manual (Page 103)

8 Extending the
Tandem DDE Gateway
110838 Tandem Computers Incorporated 8–1
You can extend the Tandem DDE Gateway in a number of ways to make developing
your client application easier. You can—
Replace the provided RSC logon dialog and associated processing. If your
application uses RSC configured security, you can develop a workstation security
dynamic link library (DLL) to work with the RSC Access Control Server that you
develop on the Tandem system.
Supplement the automatic data conversions built into the Tandem DDE Gateway
that are used with element-by-element DDE Poke and DDE Request functions.
For example, you can add 7-bit ISO 646 character translations for European
languages or decorate returned numeric data with commas and currency symbols.
You do this by developing a dynamic link library (DLL) called the User Hook
Library.
Add new automatic data conversions that will look to your client applications as if
they are built into the Tandem DDE Gateway. For example, you could add
conversions to support application-specific data types such as timestamps or data
conversions from more exotic Windows clipboard formats such as graphical
bitmap images. You do this by developing a DLL called the User Hook Library.
Use Tandem DDE Gateway Bridge directives that you embed in the DDL source of
your application’s message layouts to pass flags to your User Hook Library. You
can then test these flags in your User Hook Library code, for example, to identify
application-specific data types.
Examine and alter entire messages exchanged with Tandem servers. For example,
you can encrypt/decrypt messages, add other application specific security, or
perform workstation-based logging of messages. You do this by developing a
DLL called the User Hook Library.
Examine and change UMS messages as they arrive from the Tandem system. You
can use this feature to perform such functions as:
Message filtering
Data conversion (using other than ANSI characters)
7-bit substitutions for European characters
Message decryption
You do this by developing a dynamic link library (DLL) called the User Hook
Library.
Create client application development tools that read the workstation-based
Tandem DDE Gateway Dictionary. This is more ambitious, but you can write a
program to read the dictionary and generate client application code or to facilitate
application development in other ways.
Note The Tandem DDE Gateway Browser provides some code generation capabilities.