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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 Service

<?xml version="1.0" encoding="UTF-8"?>
<proxy name="HeaderBasedRoutingProxy" xmlns="http://ws.apache.org/ns/synapse" transports="https http" startOnLoad="true" trace="disable">
  <target>
     <!-- When a request arrives the following sequence will be followed -->   
     <inSequence>
       <switch xmlns:ns="http://org.apache.synapse/xsd" source="get-property('transport','CustomHeader')">
              <case regex="application/json">
                  <log level="custom"> 
                   <property name="'CustomHeader'" value="application/json" /> 
                  </log> 
                  <sequence key="sequence1" />
              </case>
              <case regex="text/xml">
                  <log level="custom"> 
                    <property name="'CustomHeader'" value="text/xml" /> 
                  </log> 
                  <sequence key="sequence2" />
              </case>
              <default>
              <log level="custom"> 
                  <property name="AcceptHeader" value="other" /> 
              </log> 
              <sequence key="sequence3" />
              </default>
      </switch>      
      </inSequence>
  </target>
</proxy>

Sequence 1

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

Sequence 2

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

Sequence 3

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

Send Seq

<?xml version="1.0" encoding="UTF-8"?>
<sequence xmlns="http://ws.apache.org/ns/synapse" name="send_seq"> 
    <header name="Action" scope="default" value="urn:getQuote"/>
    <call> 
      <endpoint name="simple">
       <address uri="http://localhost:9000/services/SimpleStockQuoteService"/> 
      </endpoint> 
    </call> 
</sequence>

Build and run¶

Create the artifacts:

Set up ESB Integration Studio.
Create an integration project with an ESB Configs module and an Composite Exporter.
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/CentOS
```
sh axis2server.sh
```
On Windows
```
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)

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>

Response

{"Envelope":
  {"Body":
    {"getQuoteResponse":
      {"change":-2.86843917118114,
       "earnings":-8.540305401672558,
       "high":-176.67958828498735,
       "last":177.66987465262923,
       "low":-176.30898912339075,
       "marketCap":56495579.98178506,
       "name":"IBM Company",
       "open":185.62740369461244,
       "peRatio":24.341353665128693,
       "percentageChange":-1.4930577008849097,
       "prevClose":192.11844053187397,
       "symbol":"IBM","volume":7791}
    }
  }
}

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

Request (text/xml)

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>

Response

<?xml version='1.0' encoding='UTF-8'?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
    <soapenv:Body>
        <soapenv:Envelope xmlns:ax21="http://services.samples/xsd" xmlns:ns="http://services.samples">
            <soapenv:Body>
                <ns:getQuoteResponse>
                    <ax21:change>-2.86843917118114</ax21:change>
                    <ax21:earnings>-8.540305401672558</ax21:earnings>
                    <ax21:high>-176.67958828498735</ax21:high>
                    <ax21:last>177.66987465262923</ax21:last>
                    <ax21:low>-176.30898912339075</ax21:low>
                    <ax21:marketCap>5.649557998178506E7</ax21:marketCap>
                    <ax21:name>IBM Company</ax21:name>
                    <ax21:open>185.62740369461244</ax21:open>
                    <ax21:peRatio>24.341353665128693</ax21:peRatio>
                    <ax21:percentageChange>-1.4930577008849097</ax21:percentageChange>
                    <ax21:prevClose>192.11844053187397</ax21:prevClose>
                    <ax21:symbol>IBM</ax21:symbol>
                    <ax21:volume>7791</ax21:volume>
                </ns:getQuoteResponse>
            </soapenv:Body>
        </soapenv:Envelope>
    </soapenv:Body>
</soapenv:Envelope>

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