Hi Christian,
So after looking through ActiveMQ's code it would appear that my
understanding of what constitutes a 'default entry*'* is not what I had
previously thought. As stated previously I thought that a 'default entry'
was used to define default configuration values that would be subsequently *
inherited* by specific topic and queue policy entries. The idea being that
these policy entries could optionally override these configuration values.
In other words I was interpreting 'default' to mean 'base'. This I now
know, is wrong.
It turns out that the default entry is not used for inheriting
configuration at all. Rather it is used (if defined) to configure either a
topic or queue destination when there is no corresponding destination
policy. Searching for a corresponding destination policy involves wildcard
matching the list of policy entries. Given that I have wildcard policy
entries for both topics and queues with the widest possible scope ('>') the
defaultEntry will NEVER be used, as the wildcard always results in a match.
Below is the only place that the defaultEntry is retrieved (in
PolicyMap.java):
public PolicyEntry getEntryFor(ActiveMQDestination destination) {
PolicyEntry answer = (PolicyEntry) chooseValue(destination);
if (answer == null) {
answer = getDefaultEntry();
}
return answer;
}
Do you concur with my findings?
Thanks,
Paul
On Tue, May 7, 2013 at 11:42 AM, Christian Posta
<[email protected]>wrote:
> Paul,
>
> Looks like you have a policy for all queues and all topics too... So the
> default policy won't get used for those destinations. I think you also have
> to specify a "topic" or "queue" for default entry, even though it gets
> ignored.
>
>
> On Tue, May 7, 2013 at 8:09 AM, Paul Gale <[email protected]> wrote:
>
> > Hi,
> >
> > In an attempt to DRY up my ActiveMQ configuration I realized that,
> > according to the activemq-core schema, it's possible to configure common
> > defaults for both topics and queues as shown in the snippet below. I have
> > this defined in my activemq.xml currently.
> >
> > Whilst ActiveMQ does not fail the schema validation on startup I still
> > don't know whether ActiveMQ has honored these settings or has ignored
> them.
> > I have not come across any references to this method of configuring
> common
> > defaults, nor do I have a way to verify that said configuration has taken
> > effect the way I think it has, short of relying on any explicit logging
> > statements. Would exploring ActiveMQ's MBeans via JMX be the best method
> > for verification?
> >
> > Can one of the committers comment on the legality of this syntax?
> >
> > Thanks,
> > Paul
> >
> >
> ____________________________________________________________________________________________________
> >
> > <destinationPolicy>
> > <policyMap>
> > <defaultEntry>
> > <policyEntry producerFlowControl="false"
> > advisoryWhenFull="true"
> > advisoryForFastProducers="true"
> > advisoryForSlowConsumers="true"
> > advisoryForDiscardingMessages="true"
> > optimizedDispatch="true">
> > <deadLetterStrategy>
> > <individualDeadLetterStrategy queuePrefix="DLQ."
> > topicPrefix="DLQ."
> > processExpired="false"
> >
> useQueueForQueueMessages="true"
> >
> useQueueForTopicMessages="true"
> >
> > destinationPerDurableSubscriber="false"/>
> > </deadLetterStrategy>
> > <dispatchPolicy>
> > <roundRobinDispatchPolicy/>
> > </dispatchPolicy>
> > </policyEntry>
> > </defaultEntry>
> > <policyEntries>
> > <policyEntry topic=">">
> > <dispatchPolicy>
> > <strictOrderDispatchPolicy/>
> > </dispatchPolicy>
> > </policyEntry>
> > <policyEntry queue=">" />
> > </policyEntries>
> > </policyMap>
> > </destinationPolicy>
> >
>
>
>
> --
> *Christian Posta*
> http://www.christianposta.com/blog
> twitter: @christianposta
>
