You are viewing a plain text version of this content. The canonical link for it is here.
Posted to users@activemq.apache.org by Paul Gale <pa...@gmail.com> on 2013/05/07 17:09:21 UTC
Configuring common defaults for topics and queues.
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>
Re: Configuring common defaults for topics and queues.
Posted by Christian Posta <ch...@gmail.com>.
Concur!
On Tuesday, May 7, 2013, Paul Gale wrote:
> 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
> <christian.posta@gmail.com <javascript:;>>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 <paul.n.gale@gmail.com<javascript:;>>
> 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
> >
>
--
*Christian Posta*
http://www.christianposta.com/blog
twitter: @christianposta
Re: Configuring common defaults for topics and queues.
Posted by Paul Gale <pa...@gmail.com>.
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
<ch...@gmail.com>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 <pa...@gmail.com> 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
>
Re: Configuring common defaults for topics and queues.
Posted by Christian Posta <ch...@gmail.com>.
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 <pa...@gmail.com> 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