ESB as Both a JMS Producer and Consumer

This section describes how to configure WSO2 ESB to work as a JMS-to-JMS proxy service.

Diagram 3 : Simple JMS to JMS proxy service

The following example code shows the configuration of ESB to both listen to a JMS queue and consume messages as well as to send messages to a JMS queue.

Example code 3

<proxy name="StockQuoteProxy" transports="jms">
   <target>
       <inSequence>
           <property action="set" name="OUT_ONLY" value="true"/>
           <send>
               <endpoint>
                  <address uri="jms:/SimpleStockQuoteService?transport.jms.ConnectionFactoryJNDIName=QueueConnectionFactory&amp;                 java.naming.factory.initial=org.apache.activemq.jndi.ActiveMQInitialContextFactory&amp;java.naming.provider.url=tcp://localhost:61616"/>
               </endpoint>
           </send>
       </inSequence>
   </target>
</proxy>

To place a message into a JMS queue, execute following command from <ESB_HOME>/samples/axis2Client directory.

ant stockquote -Dmode=placeorder -Dtrpurl="jms:/JMStoHTTPStockQuoteProxy?transport.jms.ConnectionFactoryJNDIName=QueueConnectionFactory&java.naming.factory.initial=org.apache.activemq.jndi.ActiveMQInitialContextFactory&java.naming.provider.url=tcp://localhost:61616&transport.jms.ContentTypeProperty=Content-Type&transport.jms.DestinationType=queue"

Generally, JMS is used for one-way, asynchronous message exchange. However you can perform synchronous messaging also with JMS. Described below is how to configure WSO2 ESB for two-way and quad-channel synchronous messaging.

JMS Synchronous Invocations : Dual Channel HTTP-to-JMS

Diagram 4 : Dual-channel JMS synchronous invocations

The following example code shows configuration of WSO2 ESB for dual-channel JMS synchronous invocations.

Example code 4

<proxy name="StockQuoteProxy" transports="http">
      <target>
          <endpoint>
                  <address uri="jms:/SimpleStockQuoteService?transport.jms.ConnectionFactoryJNDIName=QueueConnectionFactory&amp;                 java.naming.factory.initial=org.apache.activemq.jndi.ActiveMQInitialContextFactory&amp;java.naming.provider.url=tcp://localhost:61616&amp;transport.jms.DestinationType=queue&amp;transport.jms.ReplyDestination=SimpleStockQuoteServiceReply"/>
          </endpoint>
          <inSequence>
              <property action="set" name="transport.jms.ContentTypeProperty" value="Content-Type" scope="axis2"/>
          </inSequence>
          <outSequence>
              <property action="remove" name="TRANSPORT_HEADERS" scope="axis2"/>
              <send/>
          </outSequence>
      <target>
      <publishWSDL uri="file:repository/conf/sample/resources/proxy/sample_proxy_1.wsdl"/>
</proxy>

In the above example code, the ESB proxy service accepts messages via HTTP and places them in SimpleStockQuoteService JMS queue. The back-end consumes these messages from the queue and places response messages in the SimpleStockQuoteServiceReply queue. When a reply is available in the SimpleStockQuoteServiceReply queue, the ESB proxy will pick the response message and send it as the response to the client via HTTP connection.

To send a HTTP message to the ESB proxy service, execute following command from <ESB_HOME>/sample/axis2Client directory.

ant stockquote -Daddurl=http://localhost:8280/services/StockQuoteProxy -Dmode=placeorder -Dsymbol=MSFT

To co-relate request and response JMS messages, the ESB uses a JMS correlation ID internally. For more information, refer to http://www.eaipatterns.com/RequestReplyJmsExample.html.

Since this is a two-way invocation, the inSequence does not have the configuration <property action="set" name="OUT_ONLY" value="true"/>.

The response queue name is defined using transport.jms.ReplyDestination parameter in the JMS connection URL.

JMS Synchronous Invocations : Quad Channel JMS-to-JMS

Diagram 5 : Quad-channel JMS synchronous invocations

The following example code shows configuration of WSO2 ESB for quad-channel JMS synchronous invocations.

Example Code 5

<proxy name="QuadJMS" transports="jms">
      <target>
          <inSequence>
              <property action="set" name="transport.jms.ContentTypeProperty" value="Content-Type" scope="axis2"/>
              <send>
                  <endpoint>
                      <address uri="jms:/BEReq?transport.jms.ConnectionFactoryJNDIName=QueueConnectionFactory&amp;                 java.naming.factory.initial=org.apache.activemq.jndi.ActiveMQInitialContextFactory&amp;java.naming.provider.url=tcp://localhost:61616&amp;transport.jms.DestinationType=queue&amp;transport.jms.ReplyDestination=BERes"/>
                  </endpoint>
              </send>
          </inSequence>
          <outSequence>
              <send/>
          </outSequence>
      <target>
      <parameter name="transport.jms.Destination">ClientReq</parameter>
</proxy>