I think I would be a bit more inclined to look into virtual topics. Primarily because they're easier to work with - vs durable subscriptions - and they also offer the functionality provided by queues. So you get the best of both worlds ;)
Joe Ramit Arora wrote: > > Hi Joe, > Thanks for your time. My application requires a hub & spoke architecture > with around 100 publishers & 500 consumers at peak load. All publishers > would be pushing messages to different topics. One consumer would be > durable as it needs to collect all messages. The rest would be online > sporadically (actually they are end-user GUIs & I intend to stream > messages in real time to them). So I intended to make them non-durable. > What I want is that if my broker goes down, all my consumers should > failover to the slave & not loose any messages. I am using NFS based > master/slave. I am observing that my non-durable subscribers are losing > messages on failover if they are lagging behind the producers. > I am concerned about the cost of using 500 durable subscribers. I'll be > considering the use of retroactive consumers & virtual destinations. What > would be the recommended thing to do in my case? > And BTW, the user guide is awesome! > > Thanks, > Ramit > > ttmdev wrote: >> >> Your non-durable subscriber will only get those messages that were >> published while it is active. When you bounce the broker it does not >> retain the identity of your non-durable subscriber. So when the broker >> comes back up, it doesn't consider your non-durable subscriber to have >> been active when the persisted messages were published. >> >> Can you use durable subscribers? If not, look into retroactive consumers >> or better yet, virtual topics. With the latter you get the functionality >> of both a topic and queue and you don't have to worry about setting up >> unique identifiers as you would have to when using durable subscriptions. >> >> http://activemq.apache.org/virtual-destinations.html >> >> http://activemq.apache.org/retroactive-consumer.html >> >> Joe >> Goto www.ttmsolutions.com for a free ActiveMQ user guide >> >> >> >> Ramit Arora wrote: >>> >>> Hi All, >>> I have a situation where I have to consume persisent messages from many >>> non-durable subscribers. My publishers push persistent messages to a >>> topic, which are consumed asynchronously by non-durable subscribers. I >>> am using the AMQ Persistence Adapter & CLIENT_ACKNOWLEDGE. If I kill a >>> non-durable subscriber & bring it up again, some messages are lost, >>> which is expected. But consider the following case: >>> 1. Start a publisher publishing persistent messages to a topic. >>> 2. Start a non-durable subscriber which is slow compared to the >>> publisher. >>> 3. Kill the broker when 100 messages have been published but only 50 >>> have been consumed. >>> 4. Since the publisher & subscriber are failover clients, they wait for >>> the broker to come up again. >>> 5. Restart the broker. >>> 6. Try to get the remaining 50 messages to the non-durable subscriber. >>> >>> Step 6 does not work in both 5.0 & the latest 5.1 snapshot. Shouldn't >>> the remaining 50 messages be delivered? The JMS spec says: >>> "A JMS provider must deliver a PERSISTENT message once-and-only-once. >>> This >>> means a JMS provider failure must not cause it to be lost, and it must >>> not >>> deliver it twice. PERSISTENT (once-and-only-once) and NON_PERSISTENT >>> (at-most-once) >>> message delivery are a way for a JMS client to select between delivery >>> techniques that may lose a messages if a JMS provider dies and those >>> which >>> take extra effort to insure that messages can survive such a failure. >>> There is >>> typically a performance/reliability trade-off implied by this choice. >>> When a >>> client selects the NON_PERSISTENT delivery mode, it is indicating that >>> it >>> values performance over reliability; a selection of PERSISTENT reverses >>> the >>> requested trade-off." >>> >>> Queues donot suffer from this problem. Please let me know if I am >>> missing something. >>> >>> Thanks, >>> Ramit >>> >>> >>> >> >> > > -- View this message in context: http://www.nabble.com/Consuming-persistent-messages-from-a-non-durable-subscriber-tp16348721s2354p16356200.html Sent from the ActiveMQ - User mailing list archive at Nabble.com.
