HP NonStop G-Series - Manual (Page 69)

Error Handling
Creating Client Applications
110838 Tandem Computers Incorporated 4–13
same data element, and so an unsupported clipboard format is not really an error
condition.
Client application tools that hunt for supported clipboard format generally do not
return an error until they have completed their hunting and not found any supported
clipboard formats. A DDE “not processed” error that is caused by an unsupported
clipboard format will return a _TDMGW-ERROR-MSG-TYPE of N (no error). This is
the only situation when the _TDMGW-ERROR-MSG-TYPE will be N after a “not
processed” DDE error condition.
In addition to the DDE “not processed” error, the DDE Execute function with the
INITIALIZESERVICE command can also return a DDE “busy” error. This happens
when all Tandem DDE Gateway data communications resources are busy. If the DDE
“busy” error happens frequently, ensure that your client application is using the DDE
Terminate function to end all DDE conversations (even after application errors) or
increase the number of data communications sessions available (with the workstation
configuration NumberOfInterprocessSessions and NumberOfIdsSessions options).
Logging If your client application data is not getting to or from your Tandem server as
expected, you can investigate in a number of ways.
Use the Tandem INSPECT debugger to look at the data in the messages in the
Tandem server.
Use the RSC LOGEVENTS option on the various RSC objects (TERM, NETNAME,
and so on). This will show you the message flow through RSC, but not the data in
messages. For details see the RSC manuals.
Use the “Log DDE messages” option under the File menu selection in the Tandem
DDE Gateway. When you turn this option on, the DDE protocol messages
received by the Tandem DDE Gateway are logged to a disk file. You can find the
name of the disk file by clicking the “Log file name” menu selection.
To see exactly how your client application is using the DDE protocol to
communicate with the Tandem DDE Gateway, turn the “Log DDE messages”
option on, run your client application, turn the “Log DDE messages” option off,
and review the contents of the log file using a text editor such as Windows
Notepad.
Use the Microsoft DDESpy program to look at DDE traffic between your client
application and the Tandem DDE Gateway. The DDESpy program is provided with
the Microsoft Windows 3.1 Software Development Kit (SDK).
If you still have a problem (and you are a C programmer), you might consider
creating a Tandem DDE Gateway User Hook Library (see Section 8) and using
debugging tools to look at the data actually in the Tandem DDE Gateway.