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From ikbenben <ben.roo...@desato.com>
Subject Re: jdbcPersistence behaviour
Date Sat, 17 Nov 2007 10:06:58 GMT

Hey James,

thanks for the feedback.  i had read the docs.  

just to be sure i am understanding correctly, suppose we have 2 jboss nodes
in a cluster, both with activemq-ra.rar and jbossweb-tomcat55.sar deployed. 
then, when the 1st node is started, both the activemq and tomcat modules
will complete their startup correctly and be available.  however, when the
2nd node is started, it will hang indefinitely while it tries to get a db
lock for active mq and the tomcat module will never be available.  this
applies to any other services that have been deployed in the cluster (ie
jndi, webservices, scheduling, etc...)

if this is true, then it seems like there is not any reason or advantage to
embed activemq in a jboss cluster.

i would have thought it would behave similar to how ha-jms works in jboss. 
all servers in the cluster complete their startup sequence completely but
only a first node to be started in the cluster has the active jms provider. 
the other nodes in the cluster have a proxy to that first node so any
requests to the local jms gets redirected to the first node's jms provider. 
in the end all the other deployed services on every jboss node are
available.

am i understanding things correct?  what is the typical architecture then if
i have a web application deployed in a jboss cluster that needs to use jms
and i want that jms provider to be active mq?  

btw, the whole reason for this is that jbossMQ has issues and most people
have migrated to activeMQ instead.

cheers
ben


James.Strachan wrote:
> 
> On 11/11/2007, ikbenben <ben.rooney@desato.com> wrote:
>>
>> hey all,
>>
>> i've got a question regarding the behaviour of using the
>> jdbcPersistenceAdaptor.  i have deployed ActiveMQ into a clustered JBoss
>> 4.0.5 environment.  I basically have 2 JBoss servers, each of which has
>> the
>> ActiveMQ RAR deployed.  I've attached the broker xml file for reference:
>> http://www.nabble.com/file/p13696937/broker.xml broker.xml
>>
>> When i start up the JBoss servers, the first server comes up correctly
>> but
>> the second jboss instance hangs during start up while it is trying to get
>> a
>> lock on the database (activemq).  when i shut down server one, the second
>> instance continues and finishes the start up.  is this how it should
>> behave?
> 
> Yes - the first broker to start is the master, it locks the database -
> the others are slaves.
> 
> http://activemq.apache.org/jdbc-master-slave.html
> 
> If you don't want the brokers to be a master/slave cluster, then just
> use a different database for each broker; though then you probably
> will want to network your brokers together to make a store and forward
> network.
> 
> 
>> the reason i'm asking was i intended to deploy a EAR file in the jboss
>> instance on each server which would use activemq tp send messages to
>> other
>> applications.  however, if the second instance doesn't come up ever then
>> this won't work as i need to ensure i have clustering working on the EAR
>> level.
> 
> So either run your master/slave brokers separately to your jboss
> servers (e.g. running the bin/activemq command) or try figure out how
> to do an async start in jboss, or run the brokers in separate jboss
> servers? Note that the RAR can connect to a remote broker - it doesn't
> need to boot up an ActiveMQ broker
> 
> -- 
> James
> -------
> http://macstrac.blogspot.com/
> 
> Open Source SOA
> http://open.iona.com
> 
> 

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