JMS Synchronous Invocations : Dual Channel HTTP-to-JMS

A JMS synchronous invocation takes place when a JMS producer receives a response to a JMS request produced by it when invoked. The ESB Profile of WSO2 Enterprise Integrator (WSO2 EI) uses an internal JMS correlation ID to correlate the request and the response. See JMS Request/Reply Example for more information.

JMS synchronous invocations are further explained in the following use case.

Use case   

When the proxy service named SMSSenderProxy receives an HTTP request, it publishes that request in a JMS queue named SMSStore. Another proxy service named SMSForwardProxy subscribes to messages published in this queue and forwards them to a back-end service named SimpleStockQuoteService. When this back-end service returns an HTTP response, internal ESB logic is used to save that message as a JMS message in a JMS queue named SMSReceiveNotification. Then this response is taken from the SMSReceiveNotification queue and delivered to the client as an HTTP message using internal ESB logic.

The following sub sections explain how to execute this use case. Here, the Message Broker Profile of WSO2 EI is used as the JMS broker.

Prerequisites

Follow the steps below to configure the ESB Profile so that it can use the Broker Profile as the message broker. 

• Open the <EI_HOME>/conf/jndi.properties file and update the connection factories and queues as follows:

  # register some connection factories
  # connectionfactory.[jndiname] = [ConnectionURL]
  connectionfactory.QueueConnectionFactory = amqp://admin:admin@clientID/carbon?brokerlist='tcp://localhost:5675'
  
  # register some queues in JNDI using the form
  # queue.[jndiName] = [physicalName]
  queue.SMSStore=SMSStore
  queue.SMSReceiveNotificationStore=SMSReceiveNotificationStore

• Copy the following JARs from the <EI_HOME>/wso2/broker/client-lib folder to the <EI_HOME>/lib folder.
  • andes-client-3.2.19.jar
  • geronimo-jms_1.1_spec-1.1.0.wso2v1.jar
  • org.wso2.securevault-1.0.0-wso2v2.jar

Configuring the JMS publisher

Configure a proxy service named SMSSenderProxy as follows:

<proxy xmlns="http://ws.apache.org/ns/synapse"
       name="SMSSenderProxy"
       transports="https,http"
       statistics="disable"
       trace="disable"
       startOnLoad="true">
   <target>
      <inSequence>
         <property name="transport.jms.ContentTypeProperty"
                   value="Content-Type"
                   scope="axis2"/>
      </inSequence>
      <outSequence>
         <property name="TRANSPORT_HEADERS" scope="axis2" action="remove"/>
         <send/>
      </outSequence>
      <endpoint>
         <address uri="jms:/SMSStore?transport.jms.ConnectionFactoryJNDIName=QueueConnectionFactory&amp;java.naming.factory.initial=org.wso2.andes.jndi.PropertiesFileInitialContextFactory&amp;java.naming.provider.url=conf/jndi.properties&amp;transport.jms.DestinationType=queue&amp;transport.jms.ReplyDestination=SMSReceiveNotificationStore"/>
      </endpoint>
   </target>
   <description/>
</proxy>

This proxy service accepts messages sent via the HTTP transport, and stores the messages in the SMSStore queue in the Broker Profile of WSO2 EI.

The endpoint of this proxy service uses the following properties to map the proxy service with the Broker Profile.

Since this is a two-way invocation, the OUT_ONLY property is not set in the In sequence. 

Configuring the JMS consumer

Configure a proxy service named SMSForwardProxy to consume messages from the SMSStore queue of the Message Broker Profile, and forward the messages to the back-end service.

<proxy xmlns="http://ws.apache.org/ns/synapse"
       name="SMSForwardProxy"
       transports="jms"
       statistics="disable"
       trace="disable"
       startOnLoad="true">
   <target>
      <inSequence>
         <send>
            <endpoint>
               <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
            </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.ConnectionFactory">myQueueConnectionFactory</parameter>
   <parameter name="transport.jms.DestinationType">queue</parameter>
   <parameter name="transport.jms.Destination">SMSStore</parameter>
   <description/>
</proxy>

The transport.jms.ConnectionFactory, transport.jms.DestinationType parameter and the transport.jms.Destination properties parameter map the proxy service to the SMSStore queue.

The SimpleStockQuoteService sample shipped with WSO2 EI is used as the back-end service in this example. To invoke this service, the address URI of this proxy service is defined as  http://localhost:9000/services/SimpleStockQuoteService.

Deploying the sample back-end service

In this example, the SimpleStockQuoteService serves as the back-end service and receives the message from the SMSForwardProxy proxy service via the JMS transport. The response sent by the SimpleStockQuoteService is published in the SMSReceiveNotificationStore queue that is set as the value of the transport.jms.ReplyDestination parameter of the SMSSenderProxy proxy service. This allows the SMSSenderProxy to pick the response and deliver it to the client.

Follow the steps below to build and deploy the SimpleStockQuoteService:

1. Open a command prompt (or a shell in Linux) and go to the <EI_HOME>/samples/axis2Server/src/SimpleStockQuoteService directory.

2. Run ant. 

Starting the Axis2 server

Follow the steps below to start the Axis2 server:

1. Open a command prompt (or a shell in Linux) and go to the <EI_HOME>/samples/axis2Server directory.
2. Execute one of the following commands 
   
   • On Windows: axis2server.bat

   • On Linux/Solaris: ./axis2server.sh

Invoking the JMS publisher

Execute the following command from the <EI_HOME>/samples/axis2Client directory to invoke the SMSSenderProxy proxy service that you defined as the JMS publisher:

ant stockquote -Daddurl=http://localhost:8280/services/SMSSenderProxy -Dsymbol=IBM

You will see the following response:

Standard :: Stock price = $149.43669233447662