Details
Major Description
Digging into the Advisory messages we found one "missing" feature.
Network connector creates listener on Advisory topics on remote broker (and contrary for duplex NC). Listener created for topics like this:
DemandForwardingBridgeSupport.java:
368 String advisoryTopic = AdvisorySupport.CONSUMER_ADVISORY_TOPIC_PREFIX + configuration.getDestinationFilter(); 369 if (configuration.isBridgeTempDestinations()) { 370 advisoryTopic += "," + AdvisorySupport.TEMP_DESTINATION_COMPOSITE_ADVISORY_TOPIC; 371
}
This equals to the following:
ActiveMQ.Advisory.Consumer.>, ActiveMQ.Advisory.TempQueue, ActiveMQ.Advisory.TempTopic
So that, broker will be subscribed to Consumer Advisory messages for ALL queues and topics on remote broker. But really, broker interests only for those defined in dynamicallyIncludedDestinations. We have about 80 brokers connected to central. So, ALL of them subscribed to Consumer Advisory messages for ALL queues and topics. This subscriptions produce huge "flood" traffic and creates unnecessary central broker load. This could lead to connection timeouts, reconnects and as result - produce yet more advisory traffic. If brokers have tow network connectors, number of subscriptions, traffic, load will be double. After some times of work all that central broker do is dispatching advisory messages.
There is workaround. We can use "destinationFilter" attribute of networkConnector element to specify "advisory topic suffix". So, that broker will be subscribed only to
ActiveMQ.Advisory.Consumer.[destinationFilter], ActiveMQ.Advisory.TempQueue, ActiveMQ.Advisory.TempTopic
We have checked that this attribute works for duplex and "non-duplex" connectors.
The problem with this workaround is that we have to follow very specific syntax for destinationFilter.
For example, if we have tow queues defined in dynamicallyIncludedDestinations, we have to write something like:
<networkConnector uri="static:(tcp://host)" destinationFilter="Queue.outbound,ActiveMQ.Advisory.Consumer.Queue.inbound" > <dynamicallyIncludedDestinations> <queue physicalName="outbound"/> <queue physicalName="inbound"/> </dynamicallyIncludedDestinations> </networkConnector>
As you can see, syntax of "destinationFilter" is not trivial )
Feature we would like to have is that destinationFilter could be generated automatically by DemandForwardingBridgeSupport based on list of dynamicallyIncludedDestinations. So that we don`t have to specify "destinationFilter" at all.