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https://issues.apache.org/jira/browse/AMQ-6027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14997294#comment-14997294
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ASF subversion and git services commented on AMQ-6027:
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Commit cc81680e10e5c7140ec3e28091df23e9d3c3233b in activemq's branch
refs/heads/master from [~cshannon]
[ https://git-wip-us.apache.org/repos/asf?p=activemq.git;h=cc81680 ]
https://issues.apache.org/jira/browse/AMQ-6027
Adding support for consumers on virtual destinations to create network
demand. This behavior is turned off by default but can be enabled.
For example, if a consumer comes online for a queue that is part of a
VirtualTopic, this will cause a network of brokers to forward messages
because a demand subscription will be created. Same for if a consumer
comes online for a forwarded destination from a composite
destination.
There is also an option to enable flow based on the existence of a
virtual destination if the virtual destination is forwarding to a
Queue.
Full configuration instructions for this feature will be on the wiki page.
> Dynamic network demand should support Virtual Destination consumers
> -------------------------------------------------------------------
>
> Key: AMQ-6027
> URL: https://issues.apache.org/jira/browse/AMQ-6027
> Project: ActiveMQ
> Issue Type: New Feature
> Components: Broker
> Affects Versions: 5.12.1
> Reporter: Christopher L. Shannon
> Assignee: Christopher L. Shannon
> Fix For: 5.13.0
>
>
> Currently the broker supports the notion of
> {{dynamicallyIncludedDestinations}}, where messages will only be sent across
> a network of brokers if there is a consumer that exists on that destination.
> This is good because it reduces the amount of traffic if there are no
> consumers, however it doesn't take into account any virtual/composite
> destinations that might exist or the consumers on those virtual/composite
> destinations. I'd like to be able to create demand and have messages flow
> based on Virtual Destination creation, either on start up or dynamically by
> the runtime configuration plugins, or by new consumers on a Virtual
> Destination.
> So for example, if there are two brokers networked and on Broker A messages
> are published to a topic, normally those messages only get passed to Broker B
> if there is a consumer on that topic when setting
> dynamicallyIncludedDestinations to true. I want to have an option so that a
> virtual destination setup on Broker B that forwards that topic to a queue
> will trigger messages to start flowing from Broker A to Broker B.
> Messages could start flowing either simply based on the existence of the
> Virtual Destination (likely used for the case of a topic forwarding to a
> queue, so messages accumulate on the queue) or based on there being a
> consumer on the forwarded destination (likely used for the case of a queue
> forwarding to a topic).
> I've done some prototyping work here already and my plan is to keep track of
> Virtual Destination consumers (configurable by the existence of the virtual
> destination or by the fact that a real consumer exists on it) and to create a
> new advisory topic where the broker can publish consumer advisories to. The
> prefix could be called something like:
> ActiveMQ.Advisory.VirtualDestination.Consumer.Topic
> ActiveMQ.Advisory.VirtualDestination.Consumer.Queue
> Advisory messages can be sent either when virtual destinations are
> created/destroyed (kind of a dummy consumer) or when a real consumer comes
> online for a virtual destination. Then a remote broker could optionally
> listen for those advisory messages and create or destroy a
> DemandSubscription, just like is currently done for normal consumers.
> The default behavior out of the box would be to keep this behavior turned
> off, but it could optionally be turned on through configuration.
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