general newbie question

Hi,
I'm currently implementing a system that manages service contracts on 
scientific instruments.  For example, we have multiple instruments, each 
of them having its own maintenance schedule.  Each maintenance contract 
is assigned to 1 or more 'worker'.  A requirement for this system is to 
implement an automatic messaging feature that will send reminder 
messages (as email or other) to the workers a day or so before the 
scheduled maintenance.  The system will also have to send 'warning 
messages' if a scheduled maintenance has not been done on time, etc...

Here are my questions:

- Does using JMS as a message service in this scenario make any sense?
- Does OpenJMS support message scheduling?  For example, can a publisher 
put a message in openJMS for a particular topic, and say to openJMS to 
deliver this message at a specific time in the future?

If the answer to the above question is 'yes', then I also have the 
following questions:

- Is there a problem having many topics? (In the range of hundreds...)
- Once a message is sent by the producer, is there a way to cancel (or 
alter) this message before it is delivered?

Any feedback will be much appreciated.

Thanks!
    Andre

-- 
Andre Charbonneau

100 Sussex Drive, Rm 2025
Research Computing Support, IMSB
National Research Council Canada
Ottawa, ON, Canada K1A 0R6




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