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From Kuppe <ku...@360t.com>
Subject LastImage-style topic
Date Wed, 31 May 2006 12:32:31 GMT

I am trying to manage slow consumers for topics. Your documentation regarding
policyEntries suggests that it is possible to "configure the maximum number
of matched messages the broker will keep around for a consumer in addition
to its prefetch buffer" - this is called the PendingMessageLimitStrategy.
When this limit is reached it is possible to define a strategy for removing
"older messages" defined by the eviction strategy - this is called the
MessageEvictionStrategy.

I would like to use the example of a topic publishing market data for a
specific symbol but from multiple sources. It is only important that the
most recent update from each source is available to topic consumers.
Accordingly the examples shown in your slow consumer handling page are not
really relevant. I am interested that a new message simply overwrites the
previous message where the symbol and source match. This would then always
return the latest price to the consumer given the context of the producer.

>From your description it seems that the LastImageSubscriptionRecoveryPolicy
does somthing like this although only for recovering subscriptions. With the
extension of course that a specific strategy defines which messages make up
the last image set.

Is there any way that i can handle this using the features above?

In addition, if i was to define a destination policyEntry with
topic="*UpdateQuotes" will this match to all topic names that end in
"UpdateQuotes"?

Thanks in advance.
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