James Strachan ha scritto:
2008/5/8 Stefano Bagnara <[EMAIL PROTECTED]>:
I'm starting analysis on how to replace our default spool with ActiveMQ and
[...] in James we currently have a single "message store" and we can
"lock on a message" (so no other thread will take it) "retrieve it", "update
and unlock it" (alter its state or state+content) or "remove it". How would
you manage this with ActiveMQ?
With ActiveMQ you'd use a queue per state/maillet, remove it from the
queue, do something with it then put it on some other queue(s) (either
changed or the same message). The simple JMS/MOM model of sending to a
queue or consuming from a queue turns out to be very fast; allowing a
highly SEDA based asynchronous model to go really fast since there's
no locking or leasing required - and messages can flow very
asynchronously to boost throughput.
What does it happen under the hood when I use so many queues? Is the
message fully written to disk each time I move it from a queue to
another or does it simply update a reference when it belongs to the same
store?
If you do find you wanna grab - edit - put back type thing alot you
could look at using JavaSpaces (or Entity Bean :). But I think for
JAMES then messaging could work well as it sounds to me (as a newbie
JAMES person) like what you're doing processing mail is kinda a pipes
and filters type model...
http://activemq.apache.org/camel/pipes-and-filters.html
which maps very well to messaging and queues.
Cool! This is very interesting and I never read about it. So I'm going
to study it and to play with it a bit.
For more background see :
http://activemq.apache.org/camel/enterprise-integration-patterns.html
3) Outgoing spool:
The outgoing spool in JAMES is a spool like the main spool, with the
difference that a message delivery could fail and there is a retry schedule.
[...]
Any suggestions on how to do this with ActiveMQ?
It sounds like you could use the delayer pattern...
http://activemq.apache.org/camel/delayer.html
Then have separate queues for '30 mins later', '1 hour later', '2 hours later'.
[...]
I looked at the website and found an error in this page:
http://activemq.apache.org/camel/spring-xml-extensions.html
"An error occurred: Connection refused. The system administrator has
been notified."
I looked at the CWIKI sources
(http://cwiki.removeme_apache.org/confluence/display/CAMEL/Spring+XML+Extensions)
and I see this:
{snippet:id=e3|lang=xml|url=activemq/camel/trunk/components/camel-spring/src/test/resources/org/apache/camel/spring/builder/spring_route_builder_test.xml}
Not sure but maybe you have to add svn.apache.org/repos/asf/ in front of it?
I understand this is a lot of questions, but I would really appreciate any
hint, even partial. I'm collecting ideas :-)
:)
Thank you! Your answers are even more than what I expected! You're
suggestion seems to be very very useful and I think you saved me weeks
of thoughts!
I'll start with your hints and I'll come back with more questions as
soon as I'll have rode the camel! ;-)
PS: we are also evaluating using JCR for inboxes if you was wondering, but
this is another story, for another list ;-)
You could store the mail in JCR and use messaging for the process
flow. e.g. the JMS messages could just contain a reference (URL?) to
the message payload.
How often is the payload of the message mutated as it goes through
maillets? If it remains kinda static and its more the headers, states
& mailets that change mostly, it could be worth putting the payload in
some file system / REST resource / JCR and just referring to the
payload for large messages (say over 1-10MB)?
This really depends on custom configurations. We provides many mailets
that will alter the payload and many that simply run checks and route
the message. I guess an estimation of a generic use case could be this:
- 100% of messages we spool will have some of their header changed.
- 30% of messages will have their body changed a couple of times.
Very much appreciated, thank you again,
Stefano
