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Message Channels

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

Introduction to Message Channels

Message Channels facilitate communication between applications. A sender adds a message to a particular channel, which a receiver can read. Message Channels allow the sender and receiver to synchronize.

Info

For more information, see the Message Channel documentation.

Sample scenario

The sample scenario depicts how a stock inventory is made from a sender application to the receiver application through a Message Channel. The Message Channel retrieves the message content from the sender, and it allows the receiver to read the content through the Message Channel. The diagram below depicts how to simulate the sample scenario.

Message channels

Synapse configurations of the artifacts

When you unzip the ZIP file you downloaded below in Step 6 when simulating the sample scenario, you can find the below configurations in the <UNZIPPED_FILE>/src/main/wso2mi/artifacts/ directory. For more information about these artifacts, go to Develop Integration Solutions.

<?xml version="1.0" encoding="UTF-8"?>
<proxy name="message-channel-proxy" startOnLoad="true" transports="http https"
    xmlns="http://ws.apache.org/ns/synapse">
    <target>
        <inSequence>
            <sequence key="message-channel-sequence"/>
            <log level="custom">
                <property name="sending response to" value="client"/>
            </log>
            <respond/>
        </inSequence>
        <faultSequence/>
    </target>
</proxy>

<?xml version="1.0" encoding="UTF-8"?>
<sequence name="message-channel-sequence" trace="disable" xmlns="http://ws.apache.org/ns/synapse">
    <log level="custom">
        <property name="sending request to" value="axis2 server"/>
    </log>
    <call>
        <endpoint key="SimpleStockQuoteService"/>
    </call>
    <respond/>
</sequence>

<endpoint name="SimpleStockQuoteService" xmlns="http://ws.apache.org/ns/synapse">
   <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
</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. Set up the back-end service:

    1. Download the back-end service.
    2. Extract the downloaded zip file.
    3. Open a terminal, and navigate to the axis2Server/bin/ directory inside the extracted folder.
    4. Execute the following command to start the axis2server with the SimpleStockQuote back-end service:
    sh axis2server.sh

    axis2server.bat

  4. Download the artifacts of the sample.

    Download ZIP

  5. Import the artifacts to WSO2 MI.

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

  6. 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 service using SoapUI (or any other SOAP client).

POST /services/message-channel-proxy HTTP/1.1
Host: localhost:8290
SOAPAction: urn:getQuote
Content-Type: text/xml

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ser="http://services.samples" xmlns:xsd="http://services.samples/xsd">
    <soapenv:Header/>
    <soapenv:Body>
        <ser:getQuote>
            <ser:request>
                <ser:symbol>foo</ser:symbol>
            </ser:request>
        </ser:getQuote>
    </soapenv:Body>
</soapenv:Envelope>

Analyze the output

When you execute the request, the proxy service will receive the message and then route it to the back-end service (StockQuoteService). The following generated stock quote response will be received by the client application:

<?xml version='1.0' encoding='UTF-8'?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/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>-2.5477449224000654</ax21:change>
                <ax21:earnings>13.355122817579623</ax21:earnings>
                <ax21:high>194.61535812737355</ax21:high>
                <ax21:last>188.53115352495462</ax21:last>
                <ax21:lastTradeTimestamp>Tue Aug 06 10:52:05 IST 2024</ax21:lastTradeTimestamp>
                <ax21:low>-187.35545800800978</ax21:low>
                <ax21:marketCap>5.520155820141873E7</ax21:marketCap>
                <ax21:name>foo Company</ax21:name>
                <ax21:open>-184.57395642330587</ax21:open>
                <ax21:peRatio>23.15252744429442</ax21:peRatio>
                <ax21:percentageChange>-1.2212285341635047</ax21:percentageChange>
                <ax21:prevClose>208.62147019396122</ax21:prevClose>
                <ax21:symbol>foo</ax21:symbol>
                <ax21:volume>15781</ax21:volume>
            </ns:return>
        </ns:getQuoteResponse>
    </soapenv:Body>
</soapenv:Envelope>