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Command Message

This page explains how you can implement a sample scenario of Command Message EIP using WSO2 Micro Integrator.

Introduction to Command Message

The Command Message EIP allows you to use messaging to invoke a procedure in another application.

Info

For more information, see the Command Message documentation.

Command message solution

Sample scenario

This example demonstrates how the WSO2 MI uses messaging to invoke functionality provided by an application, in this case, a stock quote service. A command message can be in any form, including a JMS serialized object or a text message in the form of an XML or SOAP request. In this example, the WSO2 MI will pass the message as a document to a sample Axis2 server and invoke the operation directly using the Call mediator.

The diagram below depicts how to simulate the example scenario using the WSO2 MI.

Command message

Before digging into implementation details, let's take a look at the relationship between the example scenario and the Command Message EIP by comparing their core components.

Command Message EIP Command Message Example Scenario
Sender Stock Quote Client
Command Message Call mediator
Receiver Stock Quote Service Instance

Synapse configuration of the artifacts

Given below is the synapse configuration of this sample.

<?xml version="1.0" encoding="UTF-8"?>
<proxy name="CommandMessageProxy" startOnLoad="true" transports="http https" xmlns="http://ws.apache.org/ns/synapse">
    <target>
        <inSequence>
            <header name="Action" action="set" scope="default" value="urn:getQuote"/>
            <call>
                <endpoint key="SimpleStockEp"/>
            </call>
            <respond/>
        </inSequence>
        <faultSequence/>
    </target>
</proxy>

<?xml version="1.0" encoding="UTF-8"?>
<endpoint name="SimpleStockEp" xmlns="http://ws.apache.org/ns/synapse">
    <address uri="http://localhost:9000/services/SimpleStockQuoteService">
        <suspendOnFailure>
            <initialDuration>-1</initialDuration>
            <progressionFactor>1</progressionFactor>
        </suspendOnFailure>
        <markForSuspension>
            <retriesBeforeSuspension>0</retriesBeforeSuspension>
        </markForSuspension>
    </address>
</endpoint>

Set up the sample scenario

Follow the below instructions to simulate this sample scenario.

  1. Install WSO2 Micro Integrator.

    Info

    Follow the Install the Micro Integrator Runtime documentation for more information.

  2. Launch Visual Studio Code with the Micro Integrator for VS Code extension (MI for VS Code) installed.

    Info

    Follow the Install Micro Integrator for VS Code documentation for a complete installation guide.

  3. Download the backend service.

  4. Extract the downloaded zip file.

  5. Open a terminal, and navigate to the axis2Server/bin/ directory inside the extracted folder.

  6. Execute the following command to start the axis2server with the SimpleStockQuote backend service:

    sh axis2server.sh

    axis2server.bat

  7. Download the artifacts of the sample.

    Download ZIP

  8. Import the artifacts to WSO2 MI.

    Click File -> Open Folder -> Select the extracted ZIP file to import the downloaded ZIP file.

  9. Start the project in the WSO2 MI server.

    For instructions, go to Build and Run Documentation.

Execute the sample

Send the following request to the above proxy service.

POST /services/CommandMessageProxy HTTP/1.1
Host: localhost:8290
Content-Type: application/soap+xml

<s12:Envelope xmlns:s12="http://www.w3.org/2003/05/soap-envelope">
   <s12:Header/>
   <s12:Body>
        <ser:getQuote xmlns:ser="http://services.samples" xmlns:xsd="http://services.samples/xsd">
            <ser:request>
                <xsd:symbol>IBM</xsd:symbol>
            </ser:request>
        </ser:getQuote>
   </s12:Body>
</s12:Envelope>

Analyze the output

A message similar to the one below appears in the simple axis2server.

Tue Aug 13 14:48:29 IST 2024 samples.services.SimpleStockQuoteService :: Generating quote for : IBM

You can view the response as follows.

<?xml version='1.0' encoding='UTF-8'?>
<soapenv:Envelope xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope">
    <soapenv:Header/>
    <soapenv:Body>
        <ns:getQuoteResponse xmlns:ns="http://services.samples">
            <ns:return xmlns:ax21="http://services.samples/xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="ax21:GetQuoteResponse">
                <ax21:change>-2.9477279077218044</ax21:change>
                <ax21:earnings>12.966336060464375</ax21:earnings>
                <ax21:high>-65.04299505454664</ax21:high>
                <ax21:last>65.05264218088124</ax21:last>
                <ax21:lastTradeTimestamp>Tue Aug 13 15:38:20 IST 2024</ax21:lastTradeTimestamp>
                <ax21:low>67.23374498819649</ax21:low>
                <ax21:marketCap>4.677896775199244E7</ax21:marketCap>
                <ax21:name>IBM Company</ax21:name>
                <ax21:open>67.8880716532154</ax21:open>
                <ax21:peRatio>-19.89827532669306</ax21:peRatio>
                <ax21:percentageChange>4.592499612489774</ax21:percentageChange>
                <ax21:prevClose>-64.18569747300917</ax21:prevClose>
                <ax21:symbol>IBM</ax21:symbol>
                <ax21:volume>5381</ax21:volume>
            </ns:return>
        </ns:getQuoteResponse>
    </soapenv:Body>
</soapenv:Envelope>