Directory Change Notification - ODS-2/ODS-5

[SDIH1]

For fun I made this work using a virtual terminal (PTD stuff) enabled for SECURITY, setting an alarm ACE on the directory, and parsing the (plain text) security messages.

I never used it for real. Although polling a directory is conceptually ugly, it has several advantages:

- everybody understands how it works,
so it's well maintainable.
- No noticeable difference in system load
- No problems with bugs in exotic little
applications ( my programs sometimes
contain bugs, I am the exception here :-))
- No problems maintaining this exotic
application, and you will have to at some
point.
- No race conditions. DCL has no facilities
implementing asynchronous actions, it's
not easy to solve the problem how to
process, in DCL, the creation of 100+
files per second in a directory. O yes: by
polling!

For critical systems less is more.

[Jeremy Begg]

For the sake of completeness I'll mention that our OperCon product can be useful here.

Use a security ACE to cause an OPCOM broadcast to be generated each time the directory is updated. Then configure OperCon to watch for those broadcasts and trigger the appropriate action.

http://www.vsm.com.au/software/opercon.html

Regards,
Jeremy Begg

[labadie_1]

the correct link is

http://www.vsm.com.au/software/opercon.shtml