[jboss-dev-forums] [Design of Messaging on JBoss (Messaging/JBoss)] - Paging discussion:

[clebert.suconic@jboss.com]

I have started a WIKI for paging:

http://wiki.jboss.org/wiki/JBossMessaging2Paging

The basic idea is to have a FileBasedCollection where we store Messages, having an eviction cache based on watermark, and a FileBasedQueue for messageReferences.

Both FileBasedQueue and FileBasedCollection would share the same implementations.

I'll  use SequentialFile to access the disk, so if we decide to go AIO later we could easily change it.

One thing I'm doing differently from what I suggested on the face2face meeting was regarding the MessageReferences.

During the f2f I thought about not requiring a separated file for MessageReferences where those references would just be a pointer on the main DataFile. but then I realized that in some events the queue could eventually get out of order. (such as redelivers caused by rollbacks). So, on that case we need a separated data structure for MessageReferences.

The wiki so far only has some ideas and requirements. I will update it as soon as I have some UML diagram.



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