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From "Hiram Chirino" <>
Subject Re: Reliable multicast with JGroups and a network of brokers
Date Mon, 18 Sep 2006 21:26:31 GMT
Hi Gabriel,

The jgroups implementation from 3.x has been put in the sandbox since
it was not very popular and was not updated when the APIs changed in
the 4.x version of the broker.  If you want to take a crack at getting
it to work again please let me know and I'll point you to where the
sources are.

On 9/18/06, gabriel kastenbaum <> wrote:
> Hi everybody,
> I am rather new in ActiveMQ and I have some difficulties trying to setup
> a network of brokers using multicast and JGroups. In fact in some
> aspects I am not even very sure about how things really work.
> We have several centers communicating together using a not very reliable
> network. Every client can send and receive a message, from any part of
> the network. And the "network of brokers" should be in charge of the
> transport of the message between the brokers.
> Moreover it is a "star" network (one center and many client to send and
> receive messages)(what is the term for that kind of network?).
> So the choosen solution is to use Multicast to send messages - from the
> center to the clients. But as it has to be reliable, one thought about
> using JGroups.
> So our goal is to create a network of brokers communicating together via
> reliable multicast (jgroups).
> If someone wants to send a message or receive a message it does not have
> to connect to a remote JMS Server that could be unreableable. But It
> connects to a "local" ActiveMQ server (I mean by "local" a server on its
> local network) who will be in charge of sending the message to the
> Central Server.
> On the other sense, the client connects to the "local" JMS server to
> receive messages from the central ActiveMQ Broker.
> Thus it is not the client that deals with the not-reliable network but
> it is the ActiveMQ network of brokers. If the network between 2 servers
> is down, the client does not receive a message for a while but when the
> network is up again, it should receive the messages - that mechanism
> being transparent to the client.
> Do you think such a mechanism is doeable?
> I made first tests and it seemed to work. Here is my XML Configuration.
> <beans xmlns="">
>   <!-- Allows us to use system properties as variables in this
> configuration file -->
>   <bean
> class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"/>
>   <broker useJmx="true" brokerName="spationavActiveMQ">
>     <managementContext>
>        <managementContext connectorPort="1099"
> jmxDomainName="org.apache.activemq"/>
>     </managementContext>
>     <!-- In ActiveMQ 4, you can setup destination policies -->
>     <destinationPolicy>
>       <policyMap><policyEntries>
>           <policyEntry topic="FOO.>">
>             <dispatchPolicy>
>               <strictOrderDispatchPolicy />
>             </dispatchPolicy>
>             <subscriptionRecoveryPolicy>
>               <lastImageSubscriptionRecoveryPolicy />
>             </subscriptionRecoveryPolicy>
>           </policyEntry>
>       </policyEntries></policyMap>
>     </destinationPolicy>
>     <persistenceAdapter>
>         <journaledJDBC journalLogFiles="5"
> dataDirectory="${activemq.home}/activemq-data"/>
>     </persistenceAdapter>
>     <transportConnectors>
>        <transportConnector name="internal" uri="tcp://localhost:61616"
> discoveryUri="multicast://"/>
>     </transportConnectors>
>     <networkConnectors>
>       <!-- by default just auto discover the other brokers -->
>       <networkConnector name="default" uri="multicast://"/>
>     </networkConnectors>
>   </broker>
> </beans>
> Simple, isn't it? from now I very like the simplicity of configuration
> with activeMQ.
>  From that point I have some questions:
> - If some publish a message on that network will it be send via a
> MULTICAST protocol to the other brokers? I already read that page :
>  but I
> am not sure of the answer, because I do not understand when the protocol
> of the URI of the networkConnector is used: is it during the discovery
> of agents or during the transport of messages? Be sumerize: what is the
> protocol used during the transport of messages?
> - How to use JGroups as the transport protocol between the ActiveMQ
> brokers?  I tried to indicate for instance
>       <networkConnector name="default" uri="jgroups:default"/>
> And I added the JGRoups .jar in $ACTIVE_HOME/lib/optionnal
> But, trying to run that configuration gives an exception:
> Property 'uri' threw exception; nested exception is
> DiscoveryAgent scheme NOT recognized: [jgroups]
> Did I tryed to configure jgroups at a worng place? Where must I
> configure the jgroups aspects?
> Or may be I misunderstood some concepts? In that case please let me know.
> Thanks in advance.
> Gabriel.



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