IDIspatchMessageInspector

Question

I Implement IDispatchMessageInspector.AfterReciveRequest Then I configur like this :

<configuration>
  <system.serviceModel>
    <services>
      <service 
        name="Microsoft.WCF.Documentation.SampleService"
        behaviorConfiguration="inspectorBehavior">
        <host>
          <baseAddresses>
            <add baseAddress="http://localhost:8080/SampleService" />
          </baseAddresses>
        </host>
        <endpoint
          address=""
          binding="wsHttpBinding"
          contract="Microsoft.WCF.Documentation.ISampleService"
        />

      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior name="inspectorBehavior">
          <serviceInspectors />
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <extensions>
      <behaviorExtensions>
        <add 
          name="serviceInspectors" 
          type="Microsoft.WCF.Documentation.InspectorInserter, HostApplication, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null"
        />
      </behaviorExtensions>
    </extensions>
  </system.serviceModel>
</configuration>

but it doesnt work I check in my assembly and in my local reference and I didnt found Microsoft.WCF.Documentation.InspectorInserter or HostApplication dll I search in the net to download HostApplication dll but I didnt found nothing.

What I have to do? I need to implement more thing or I Just need this configuration . And how I fount HostApplication dll pleas help my thankkks