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Tim Bain commented on AMQ-2711: ------------------------------- If you force `conduitSubscriptions=true` for topics, you lose the ability to ensure that only messages that actually have a consumer on broker A will be forwarded from broker B, which could be important if there's a bandwidth-limited link between the two. With `conduitSubscriptions=true`, selectors are ignored and *all* messages are passed from B to A, even if all consumers on A have selectors that will exclude the message. In certain scenarios the duplicate messages that could result from setting `conduitSubscriptions=false` would be better than the use of limited bandwidth to pass messages that will be immediately discarded on broker A. And it's not "almost inevitable" that `conduitSubscriptions=false` will case problems; you won't get duplicate messages if all consumers have unique selectors such that a message is only ever delivered to a singe consumer. Allowing both values of `conduitSubscriptions` for both destination types doesn't hurt anything and it gives configuration options that are useful in certain situations, so let's close this as Won't Fix. > conduitSubscriptions flag on networkConnector element should only affect > queues, not topics > ------------------------------------------------------------------------------------------- > > Key: AMQ-2711 > URL: https://issues.apache.org/jira/browse/AMQ-2711 > Project: ActiveMQ > Issue Type: Improvement > Components: Connector > Affects Versions: 5.3.1 > Reporter: Fintan Bolton > Fix For: 5.x > > > In the doc for 'Networks of Brokers', > http://activemq.apache.org/networks-of-brokers.html, it says that it is > sometimes useful to disable {{conduitSubscriptions}} for queues, because this > gives you a better load balancing effect when consumers are attached to > various points in the broker network. The only trouble is, currently it does > not seem practical to disable {{conduitSubscriptions}}, because this almost > inevitably causes trouble with topics. That is, it can easily happen that > topic messages are duplicated, if {{conduitSubscriptions}} is set to > {{false}}. > It seems like it would be better if topic subscriptions where *always* > treated as conduits and the {{conduitSubscriptions}} attribute only affected > queue subscriptions. That way, you could happily disable conduits for queues > while leaving it enabled for topics. > A bit of investigation is probably needed, however, to make sure that there > aren't any edge cases where you might actually want to disable conduit > subscriptions for topics. -- This message was sent by Atlassian JIRA (v6.3.4#6332)