Sample 12: One-Way Messaging in a Fire-and-Forget Mode through ESB

Introduction

This sample demonstrates how one-way messaging can be done in a  fire-and-forget mode through the ESB.

Prerequisites

For a list of prerequisites, see Prerequisites to start the ESB samples.

Building the sample

The XML configuration for this sample is as follows: 

<definitions xmlns="http://ws.apache.org/ns/synapse">
  <sequence name="main">
    <in>
      <property name="FORCE_SC_ACCEPTED" value="true" scope="axis2" /> 
      <property name="OUT_ONLY" value="true"/>
      <send>
        <endpoint>
           <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
        </endpoint>
      </send>
    </in>
  </sequence>
</definitions>

This configuration file  synapse_sample_12.xml is available in the <ESB_HOME>/repository/samples directory.

To build the sample

1. Start the ESB with the sample 12 configuration. For instructions on starting a sample ESB configuration, see Starting the ESB with a sample configuration.
   
   The operation log keeps running until the server starts, which usually takes several seconds. Wait until the server has fully booted up and displays a message similar to "WSO2 Carbon started in n seconds."

2. Start the Axis2 server. For instructions on starting the Axis2 server, see Starting the Axis2 server.

3. Deploy the back-end service SimpleStockQuoteService. For instructions on deploying sample back-end services, see Deploying sample back-end services.

   Now you have a running ESB instance and a back-end service deployed. In the next section, we will send a message to the back-end service through the ESB using a sample client.

Executing the sample

The sample client used here is the Stock Quote Client, which can operate in several modes. For further details on this sample client and its operation modes, see Stock Quote Client.

This sample invokes the one-way placeOrder operation on the SimpleStockQuoteService using the custom client which uses the Axis2 ServiceClient.fireAndForget() API.

To execute the sample client

• Run the following command from the <ESB_HOME>/samples/axis2Client directory.

  ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/ -Dmode=placeorder

Analyzing the output

Analyze the Axis2 server log.

You will see that the one-way message flows through the ESB into the sample Axis2 server instance, which reports the acceptance of the order as follows: 

SimpleStockQuoteService :: Accepted order for : 7482 stocks of IBM at $ 169.27205579038733

If you send the client request through TCPmon,  you will see that the SimpleStockQuoteService replies to the ESB with a HTTP 202 reply and then the ESB in turn replies to the client with a HTTP 202 acknowledgement.