What about using virtual topics instead of topics? This way, all your consumers consume from queues.
Joe http://www.ttmsolutions.com MatsH wrote: > > Hey, > > We use both topics and queues alongside selectors, ActiveMQ 5.2, and we > were intending to go live using a network of brokers and the clients > using the failover: protocol. > > Unfortunately, due to how conduit subscriptions work we will start with > a single broker for now, until we can figure out a good way of doing it. > The problem is that conduit subscriptions make it difficult to use > either topics or queues depending on if you have it set to on or off. > > For instance, with conduit subscriptions turned off, you get duplicate > messages. This quickly gets out of hand if you add more brokers. If you > have two consumers on broker A and send a message to their topic on > broker B, each consumer receives the message twice. If you add another > broker and send the message to one of the brokers that is remote to the > consumers each consumer now gets 6 messages. Add another consumer and > each consumer now gets the message 12 times, etc. It very quickly gets > out of hand, so having conduit subscriptions turned off is a no go. > > On the other hand, with conduit subscriptions turned on you now run into > problems with queues. With two consumers on broker A and one consumer on > broker B the messages get distributed unevenly, if 20 messages are sent > to broker B its lone consumer gets 10 messages, and the other 10 are > sent to broker A where each consumer only gets 5 messages each. > Furthermore if you are using selectors (which we are) then if it so > happened that the 10 messages that went to the consumers on broker A > didn't match the selectors then those 10 messages would just be stuck on > the queue on broker A. So having conduit subscriptions turned on is > firstly impractical since the messages to queues are distributed > unevenly, and if you are using selectors it doesn't work at all. > > So the situation we are in is that we can't have conduit subscriptions > turned on because of our queues and we can't have it turned off because > of our topics. Yes we could refactor and stop using selectors, but our > messages would still be distributed unevenly. > > It strikes me that if conduit subscriptions could be turned on and off > independently between queues and topics things would work; we could have > it turned on for topics and off for queues, and everything would work. > > For those of you that have looked more at the ActiveMQ internals than I > have, would this be a difficult change to make? > > > -- > Mats Henrikson > Software Engineer > SunGard Kiodex > > Think before you print > > > > -- View this message in context: http://www.nabble.com/conduit-subscriptions-tp24921302p24925514.html Sent from the ActiveMQ - User mailing list archive at Nabble.com.
