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From "James Strachan" <>
Subject Re: MessageQuery interface question
Date Tue, 04 Apr 2006 15:31:36 GMT
On 4/4/06, vik Dhawan <> wrote:
> I see a interface called MessageQuery, i dont see any implimentation to this
> inteface i would like to know what is its role in the activeMQ.

Its used by the QueryBasedSubscriptionRecoveryPolicy to allow
arbitrary initial messages to be created and dispatched to a consumer
when a subscription starts. e.g. to read out the initial state of a
system from a database or something. Topics are often used to publish
updates to state as the system runs; this hook allows you to send the
initial state to a consumer when it starts up.

> i would like to understand class XQueryExpression also i may be able the
> documentation.

This class isn't fully implemented yet - its idea is to support XQuery
based selectors; so far only XPath selectors are implemented.



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