On Tue, Mar 18, 2008 at 7:50 AM, Fullocto <[EMAIL PROTECTED]> wrote: > > Dear all, > > I have been working on ESB/JBI for some weeks. I tried to understand the > fundamental notions and I think I figured out thanks notably to the > servicemix website. > > However I can not guess what is hidden under the "distributed ESB"? I read > it is using ActiveMQ, but reading the activemq.apache.org webpages didn't > really help me. > What I can imagine is: > - the NMR is extended through different physical servers/JVM; > - one service can communicate with another one remotely. > What I have inferred: > - there is one common registry that knows which components and which service > assemblies are started on the bus. > What I have no idea about: > - what do failover and load balancing mean? when a component fails/stops, it > is started on another server (without losing the messages ) ?
You've basically got it correct. Multiple instances of ServiceMix can be networked together using a network of brokers with ActiveMQ (http://activemq.apache.org/networks-of-brokers.html). When doing this, the NMR is effectively a single logical router across all the networked instances of ServiceMix where the NMR then has knowledge of all the SAs deployed in all instances of ServiceMix. Because it knows where each SA is located, the NMR can then easily route to a service in a given instance of ServiceMix in a transparent manner. WRT failover and load balancing, this is achieved through the use of JMS semantics using the servicemix-jms component and container configuration. With the correct configuration, failover across containers can be configured so that messages are not dropped. Load balancing is achieved through the use of queues by employing multiple servicemix-jms consumers on a single queue. -- perl -e 'print unpack("u30","D0G)[EMAIL PROTECTED]&5R\"F)R=6-E+G-N>61E<D\!G;6%I;\"YC;VT*" );' Apache ActiveMQ - http://activemq.org/ Apache Camel - http://activemq.org/camel/ Apache ServiceMix - http://servicemix.org/ Apache Geronimo - http://geronimo.apache.org/ Blog: http://bruceblog.org/
