HP OpenVMS Systems

Debugging detached processes?

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The Question is:

 
I have an online application written using DEC C and FMS.  I have no
problems debugging this application.  However, some of the screens in the
online application send DEC message queue messages (REQUEST) and wait until
it receives a RESPONSE to the messag
e it sent.  There is a detached process which acts as a message handler.  It
continuously reads the messages from the queue that my online programs and
other batch programs  send to, processes it according to the message type
and sends a response.  Then t
he online program can continue and process the data sent in the message
response.
What I need to do is to be able to debug the detached process, which is the
message handling program.  I have tried various methods such as trying to
attach to the detached process but VMS didn't allow it.  Do you have any
suggestions on what to do?
 
 

The Answer is :

 
  The OpenVMS Debugger can be run remotely, passing a workstation (WSA0:)
  device name as part of the detached process startup (/OUTPUT=WSAn:),
  passing a DECterm (created via a call to the DECw$Term_Port routine or
  via CREATE/TERMINAL), passing the target device to the debugger via the
  DBG$* logical names, starting up the detached process from within a
  (temporary) DCL procedure containing the appropriate SET DISPLAY command,
  or various other techniques.
 
  For example:
 
    $ SET DISPLAY/CREATE[/EXECUTIVE]...
    $ wsa = f$trnln("DECW$DISPLAY")
    $ RUN image/DETACH/INPUT=NLA0:/OUTPUT='wsa' ...
 
  As there is no way to interrupt the detached process via CTRL/C or CTRL/Y,
  you may want to provide a way for the application to perform a call to
  lib$signal( SS$_DEBUG ) to invoke the debugger.  (Search for "SS$_DEBUG"
  in the appendix of the debugger manual for details.)
 

  

     

     
answer written or last revised on ( 13-SEP-1999 )
     
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