Silverlight 4 with (HTTP) Duplex and SQL Notifications

<?xml version="1.0"?>
<!--<configuration>

  <system.web>
    <compilation debug="true" targetFramework="4.0" />
  </system.web>
  <system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          --><!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment --><!--
          <serviceMetadata httpGetEnabled="true"/>
          --><!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information --><!--
          <serviceDebug includeExceptionDetailInFaults="false"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
  </system.serviceModel>
 <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
  </system.webServer>
  
</configuration>-->

<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.0" />
  </system.web>

  <system.serviceModel>
    <client />
    <extensions>
      <bindingExtensions>
        <add name="pollingDuplexHttpBinding" type="System.ServiceModel.Configuration.PollingDuplexHttpBindingCollectionElement, System.ServiceModel.PollingDuplex, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
      </bindingExtensions>
    </extensions>
    <behaviors>
      <serviceBehaviors>
        <behavior  name="wcfDuplex.DuplexServiceBehavior">
          <serviceMetadata httpGetEnabled="true" />
          <serviceDebug includeExceptionDetailInFaults="true" />
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <bindings>
      <pollingDuplexHttpBinding>
        <binding name="multipleMessagesPerPollPollingDuplexHttpBinding" maxOutputDelay="00:00:07" duplexMode="MultipleMessagesPerPoll" />
      </pollingDuplexHttpBinding>
    </bindings>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="false"/>
     
    <services>
      <service name="wcfDuplex.Duplex" behaviorConfiguration="wcfDuplex.DuplexServiceBehavior">      
        <!-- Service Endpoints -->
        <endpoint
           address=""
           binding="pollingDuplexHttpBinding"
           bindingConfiguration="multipleMessagesPerPollPollingDuplexHttpBinding"
           contract="wcfDuplex.IDuplexService">
        </endpoint>
        <endpoint
            address="mex"
            binding="mexHttpBinding"
            contract="IMetadataExchange"/>
      </service>
    </services>
    
  </system.serviceModel>
</configuration>