WCF routing service

Lets say you have 2 service - Service1.svc and Service2.svc both having the same service contract. Based on the request, you would route it to Service1 or Service2.

For this scenario, WCF has the feature of Routing Service. You create a third service (say Service.svc ) which will not have any code but some configuration to parse the request XML by Xpath and sending the request to the desired service.

Below is a sample config for a Routing service which routes based on the value of applicationType which is a parameter in the Service contract.  –

<system.serviceModel>

    <behaviors>

      <serviceBehaviors>

        <behavior name="RoutingBehavior">

          <serviceMetadata httpGetEnabled="True"/>

          <routing routeOnHeadersOnly="false" filterTableName="ApplicationRoutingTable" />

          <serviceDebug includeExceptionDetailInFaults="true" />

        </behavior>

      </serviceBehaviors>

    </behaviors>

    <routing>

      <namespaceTable>

        <add namespace="http://mikedemo/contracts" prefix="o"/>

      </namespaceTable>

      <filters>

        <filter name="XYZApplicationFilter" filterType="XPath" filterData="//o:applicationType = 'XYZ'"/>

        <filter name="NonXYZApplicationFilter" filterType="XPath" filterData="//o:applicationType != 'XYZ'"/>

      </filters>

      <filterTables>

        <filterTable name="ApplicationRoutingTable">

          <add filterName="XYZApplicationFilter" endpointName="XYZApplication" priority="0" />

          <add filterName="NonXYZApplicationFilter" endpointName="NonXYZApplication" priority="0" />

        </filterTable>

      </filterTables>

    </routing>

    <services>

      <service behaviorConfiguration="RoutingBehavior" name="System.ServiceModel.Routing.RoutingService">

        <endpoint binding="basicHttpBinding" bindingConfiguration=""   name="RoutingEndpoint" contract="System.ServiceModel.Routing.IRequestReplyRouter" />

        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"  />

      </service>

    </services>

    <client>

      <endpoint name="XYZApplication" contract="*" binding="basicHttpBinding" address="http://localhost/WcfServiceA/Service2.svc" />

      <endpoint name="NonXYZApplication" contract="*" binding="basicHttpBinding" address="http://localhost/WcfServiceA/Service1.svc" />

    </client>

  </system.serviceModel>

When you want to use the “Routing Service”, just add a reference to any of Service1 or Service2 to generate the metadata. At the end, just modify the endpoint in web.config to point to the Routing Service instead of Service1 or Service2.