Hi Folks,
When configuring ESB JMS transport parameters (JMSSender and JMSListener)
for Topics with durable subscription I came across following scenario. If
we define single TopicConnectionFactory in axis2.xml as follows,
<parameter name="myTopicConnectionFactory" locked="false">
<parameter name="java.naming.factory.initial"
locked="false">org.apache.activemq.jndi.ActiveMQInitialContextFactory</parameter>
<parameter name="java.naming.provider.url"
locked="false">tcp://localhost:61616</parameter>
<parameter name="transport.jms.ConnectionFactoryJNDIName"
locked="false">TopicConnectionFactory</parameter>
<parameter name="transport.jms.ConnectionFactoryType"
locked="false">topic</parameter>
<parameter name="transport.jms.SessionTransacted"
locked="false">true</parameter>
<parameter name="transport.jms.SessionAcknowledgement"
locked="true">CLIENT_ACKNOWLEDGE</parameter>
<parameter name="transport.jms.SubscriptionDurable"
locked="false">true</parameter>
<parameter name="transport.jms.DurableSubscriberClientID"
locked="false">myTopicDurableClient1</parameter>
<parameter name="transport.jms.DurableSubscriberName"
locked="false">myTopicDurableSubscriber1</parameter>
</parameter>
and then refer this connection factory from multiple proxy services
(Listeners) then all will share the same client ID which causes ESB to
continuously throw the following exception as it trying to reconnect to the
same client ID.
[2013-05-09 11:01:15,653] ERROR - NativeWorkerPool Uncaught exception
org.apache.axis2.transport.jms.AxisJMSException: Error acquiring a JMS
connection to : TopicConnectionFactory using JNDI properties :
{java.naming.factory.initial=org.apache.activemq.jndi.ActiveMQInitialContextFactory,
serviceType=proxy, transport.jms.ConnectionFactoryType=topic,
transport.jms.DestinationType=topic,
transport.jms.ConnectionFactory=myTopicConnectionFactory,
java.naming.provider.url=tcp://localhost:61616,
transport.jms.SessionAcknowledgement=CLIENT_ACKNOWLEDGE}
at
org.apache.axis2.transport.jms.ServiceTaskManager.handleException(ServiceTaskManager.java:1000)
at
org.apache.axis2.transport.jms.ServiceTaskManager.access$700(ServiceTaskManager.java:50)
at
org.apache.axis2.transport.jms.ServiceTaskManager$MessageListenerTask.createConnection(ServiceTaskManager.java:835)
at
org.apache.axis2.transport.jms.ServiceTaskManager$MessageListenerTask.getConnection(ServiceTaskManager.java:697)
at
org.apache.axis2.transport.jms.ServiceTaskManager$MessageListenerTask.receiveMessage(ServiceTaskManager.java:496)
...........................
Caused by: javax.jms.InvalidClientIDException: Broker: localhost - Client:
myTopicDurableClient1 already connected from /127.0.0.1:52919
at
org.apache.activemq.broker.region.RegionBroker.addConnection(RegionBroker.java:243)
at
org.apache.activemq.broker.BrokerFilter.addConnection(BrokerFilter.java:85)
at
org.apache.activemq.advisory.AdvisoryBroker.addConnection(AdvisoryBroker.java:66)
at
org.apache.activemq.broker.BrokerFilter.addConnection(BrokerFilter.java:85)
at
org.apache.activemq.broker.BrokerFilter.addConnection(BrokerFilter.java:85)
.............................
This happens because DurableSubscriberClientID and DurableSubscriberName
should be unique for a subscriber. But this mis-configuration causes ESB
performance downgrade in general (ie - ESB web console to perform sluggish)
. So since it is obvious that Client ID must be uniquely defined and no
point of continuous reconnection as result will be the same until it is
reconfigured.
So isn't it better to implement a fail safe scenario for this such as,
1. Terminating deployment of the proxy services
2. limit the reconnection attempts
3. Internally generate unique Client ID if there is a conflict
Thanks,
Malith
--
Malith Dhanushka
Software Engineer
*WSO2, Inc. : wso2.com*
lean.enterprise.middleware.
*Blog* : mmalithh.blogspot.com
*Linked-i*n : http://lk.linkedin.com/in/malithd
*Twitter* : https://twitter.com/MalithWD
*Mobile* : +94 716 506 693
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