Routing Based on Message Headers¶

This example scenario uses an inventory of stocks as the back-end service. A proxy service is configured in the Micro Integrator to use separate mediation sequences for processing request messages with different message headers.

When a stock quote request is received, the Micro Integrator will read the request header and then route the message to the relevant mediation sequence for processing. The relevant sequence will forward the message to the backend, receive the response, process it, and return it to the client.

Synapse configuration¶

Listed below are the synapse configurations for implementing this scenario. See the instructions on how to build and run this example.

Proxy ServiceSequence 1Sequence 2Sequence 3Send SeqEndpoint

<?xml version="1.0" encoding="UTF-8"?>
<proxy name="HeaderBasedRoutingProxy" startOnLoad="true" transports="http https" xmlns="http://ws.apache.org/ns/synapse">
    <target>
        <inSequence>
            <switch source="get-property('transport','CustomHeader')">
                <case regex="application/json">
                    <log category="INFO" level="custom">
                        <property name="CustomHeader" value="application/json"/>
                    </log>
                    <sequence key="sequence1"/>
                </case>
                <case regex="text/xml">
                    <log category="INFO" level="custom">
                        <property name="CustomHeader" value="text/xml"/>
                    </log>
                    <sequence key="sequence2"/>
                </case>
                <default>
                    <log category="INFO" level="custom">
                        <property name="AcceptHeader" value="other"/>
                    </log>
                    <sequence key="sequence3"/>
                </default>
            </switch>
        </inSequence>
        <faultSequence/>
    </target>
</proxy>

<?xml version="1.0" encoding="UTF-8"?>
<sequence name="sequence1" trace="disable" xmlns="http://ws.apache.org/ns/synapse">
    <sequence key="send_seq"/>
    <property name="messageType" scope="axis2" type="STRING" value="application/json"/>
    <respond/>
</sequence>

<?xml version="1.0" encoding="UTF-8"?>
<sequence name="sequence2" trace="disable" xmlns="http://ws.apache.org/ns/synapse">
    <sequence key="send_seq"/>
    <property name="messageType" scope="axis2" type="STRING" value="text/xml"/>
    <respond/>
</sequence>

<?xml version="1.0" encoding="UTF-8"?>
<sequence name="sequence3" trace="disable" xmlns="http://ws.apache.org/ns/synapse">
    <sequence key="send_seq"/>
    <respond/>
</sequence>

<?xml version="1.0" encoding="UTF-8"?>
<sequence name="send_seq" trace="disable" xmlns="http://ws.apache.org/ns/synapse">
    <header name="Action" action="set" scope="default" value="urn:getQuote"/>
    <call>
        <endpoint key="stockQuoteEndpoint"/>
    </call>
</sequence>

<?xml version="1.0" encoding="UTF-8"?>
<endpoint name="stockQuoteEndpoint" 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>

Build and run¶

Create the artifacts:

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.
Create an integration project.
Create the proxy service and mediation sequences with the configurations given above.
Deploy the artifacts in your Micro Integrator.

Set up the back-end service:

Download the back-end service.
Extract the downloaded zip file.
Open a terminal, navigate to the axis2Server/bin/ directory inside the extracted folder.
Execute the following command to start the axis2server with the SimpleStockQuote back-end service:
On MacOS/Linux/CentOSOn Windows
sh axis2server.sh
axis2server.bat

Invoke the proxy service:

Send a request with the 'application/json' header and see that a JSON response is received.

Request (application/json)Response

HTTP method: POST 
Request URL: http://localhost:8290/services/HeaderBasedRoutingProxy
Content-Type: text/xml;charset=UTF-8
CustomHeader: application/json
Message Body:
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
   <soapenv:Header/>
   <soapenv: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>
   </soapenv:Body>
</soapenv:Envelope>

{
    "Envelope": {
        "Header": null,
        "Body": {
            "getQuoteResponse": {
                "return": {
                    "@type": "ax21:GetQuoteResponse",
                    "change": 3.8274925074699615,
                    "earnings": 12.497082213279025,
                    "high": -161.41346745041102,
                    "last": 164.53738820320592,
                    "lastTradeTimestamp": "Mon Jul 01 16:12:23 IST 2024",
                    "low": -163.2629771689784,
                    "marketCap": -4291974.770736802,
                    "name": "IBM Company",
                    "open": 172.25384297431248,
                    "peRatio": 25.33375650150598,
                    "percentageChange": 2.156561954110794,
                    "prevClose": 177.4812219131509,
                    "symbol": "IBM",
                    "volume": 19678
                }
            }
        }
    }
}

Send a request with the 'text/xml' header and see that an XML response is received.

Request (text/xml)Response

HTTP method: POST 
Request URL: http://localhost:8290/services/HeaderBasedRoutingProxy
Content-Type: text/xml;charset=UTF-8
CustomHeader: text/xml
Message Body:
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
   <soapenv:Header/>
   <soapenv: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>
   </soapenv:Body>
</soapenv:Envelope>

<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>4.131871430984311</ax21:change>
                <ax21:earnings>13.582164597035094</ax21:earnings>
                <ax21:high>-160.71069227737433</ax21:high>
                <ax21:last>162.56566544816462</ax21:last>
                <ax21:lastTradeTimestamp>Mon Jul 01 16:19:44 IST 2024</ax21:lastTradeTimestamp>
                <ax21:low>166.6876727232271</ax21:low>
                <ax21:marketCap>3.630109155595136E7</ax21:marketCap>
                <ax21:name>IBM Company</ax21:name>
                <ax21:open>-161.08473734270993</ax21:open>
                <ax21:peRatio>24.51306734205319</ax21:peRatio>
                <ax21:percentageChange>-2.622518084027564</ax21:percentageChange>
                <ax21:prevClose>-157.55359157099647</ax21:prevClose>
                <ax21:symbol>IBM</ax21:symbol>
                <ax21:volume>5552</ax21:volume>
            </ns:return>
        </ns:getQuoteResponse>
    </soapenv:Body>
</soapenv:Envelope>