JMS Synchronous Invocations : Quad Channel JMS-to-JMS

Introduction

The following diagram depicts quad-channel JMS synchronous invocations of the WSO2 Enterprise Integrator (WSO2 EI).

Prerequisites

Follow the steps below to set the prerequisites up before you start.

Download and set up Apache ActiveMQ. For instructions, see Installation Prerequisites.
Copy the following client libraries from the <AMQ_HOME>/lib directory to the <EI_HOME>/libdirectory.
ActiveMQ 5.8.0 and above
- - activemq-broker-5.8.0.jar
  - activemq-client-5.8.0.jar
  - geronimo-jms_1.1_spec-1.1.1.jar
  - geronimo-j2ee-management_1.1_spec-1.0.1.jar
  - hawtbuf-1.9.jar
Earlier versions of ActiveMQ
- - activemq-core-5.5.1.jar
  - geronimo-j2ee-management_1.0_spec-1.0.jar
  - geronimo-jms_1.1_spec-1.1.1.jar
Add the following properties to the <EI_HOME>/conf/jndi.properties file. For more information, see Setting up WSO2 EI and ActiveMQ.
```
queue.ClientReq = ClientReq
queue.BEReq = BEReq
queue.BERes = BERes
```

Uncomment the following sections in the <EI_HOME>/conf/axis2/axis2.xml file.

To enable the JMS transport sender:

<transportSender name="jms" class="org.apache.axis2.transport.jms.JMSSender"/>

To enable the JMS transport listener:

<!--Uncomment this and configure as appropriate for JMS transport support, after setting up your JMS environment (e.g. ActiveMQ)--><transportReceiver name="jms" class="org.apache.axis2.transport.jms.JMSListener">
       <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>
  
       <parameter name="myQueueConnectionFactory" 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">QueueConnectionFactory</parameter>
            <parameter name="transport.jms.ConnectionFactoryType" locked="false">queue</parameter>
       </parameter>
  
       <parameter name="default" 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">QueueConnectionFactory</parameter>
            <parameter name="transport.jms.ConnectionFactoryType" locked="false">queue</parameter>
       </parameter>
   </transportReceiver>

Sample configuration

Following is a sample configuration of WSO2 EI for quad-channel JMS synchronous invocations.

Example Code 5

<proxy name="QuadJMS" transports="jms" xmlns="http://ws.apache.org/ns/synapse">
      <target>
          <inSequence>
              <property action="set" name="transport.jms.ContentTypeProperty" value="Content-Type" scope="axis2"/>
              <log level="full" xmlns="http://ws.apache.org/ns/synapse"/>
              <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.ContentType">
          <rules>
              <jmsProperty>contentType</jmsProperty>
              <default>text/xml</default>
          </rules>
      </parameter>
      <parameter name="transport.jms.Destination">ClientReq</parameter>
</proxy>

The message flow of the above sample configuration is as follows:

The JMSReplyTo property of the JMS message is set to ClientRes. Therefore, the client sends a JMS message to the ClientReq queue.
The transport.jms.ReplyDestination value is set to BERes. This enables the WSO2 EI proxy to pick messages from ClientReq queue, and send to BEReq queue .
The back-end picks messages from the BEReq queue, processes and places response messages to BERes queue.
Once a response is available in BERes queue, the proxy service picks it and sends back to ClientRes queue.
The client picks it as the response message.

Note that there are two ways to define the endpoint URL:

Specify the JNDI name of the JMS queue and the connection factory parameters in the connection URL as shown in the sample configuration given above.
If you have already specified the endpoint's connection factory parameters (for the JMS sender configuration) in the axis2.xml file (stored in the <EI_HOME>/conf/axis2/ directory), the connection URL in the proxy service should be as shown below. In this example, the endpoint URL of the proxy service refers the relevant connection factory in the axis2.xml file:
When the broker is ActiveMQ
```
jms:transport.jms.ConnectionFactory=QueueConnectionFactory
```
When the broker is WSO2 MB
```
jms:/BEReq?transport.jms.ConnectionFactory=QueueConnectionFactory
```

Be sure to replace the '&' character in the endpoint URL with '&' to avoid the following exception:

com.ctc.wstx.exc.WstxUnexpectedCharException: Unexpected character '=' (code 61); expected a semi-colon after the reference for entity 'java.naming.factory.initial' at [row,col {unknown-source}