How to: Inspect or Modify Parameters

Article
09/15/2021

You can inspect or modify the incoming or outgoing messages for a single operation on a Windows Communication Foundation (WCF) client object or a WCF service by implementing the System.ServiceModel.Dispatcher.IParameterInspector interface and inserting it into the client or service runtime. Typically an operation behavior is used to add parameter inspectors for a single operation; other behaviors can be used to provide easy access to the runtime at a greater scope. For more information, see Extending Clients and Extending Dispatchers.

Inspecting or Modifying Parameters

Implement the System.ServiceModel.Dispatcher.IParameterInspector interface.
Implement a System.ServiceModel.Description.IOperationBehavior, System.ServiceModel.Description.IEndpointBehavior, System.ServiceModel.Description.IServiceBehavior or System.ServiceModel.Description.IContractBehavior (depending upon the required scope) to add your parameter inspector to either the ClientOperation.ParameterInspectors or DispatchOperation.ParameterInspectors properties.
Insert your behavior prior to calling ClientBase<TChannel>.Open or the ICommunicationObject.Open method on the System.ServiceModel.ChannelFactory<TChannel>. For details, see Configuring and Extending the Runtime with Behaviors.

Example

The following code examples show, in order:

A parameter inspector implementation.
The behavior implementation that inserts the parameter inspector using a System.ServiceModel.Description.IOperationBehavior, System.ServiceModel.Description.IEndpointBehavior, and an System.ServiceModel.Description.IServiceBehavior.
A configuration file that loads and runs the endpoint behavior in a client application to insert the parameter inspector on the client.

#region IParameterInspector Members
public void AfterCall(string operationName, object[] outputs, object returnValue, object correlationState)
{
  Console.WriteLine(
    "IParameterInspector.AfterCall called for {0} with return value {1}.",
    operationName,
    returnValue.ToString()
  );
}

public object BeforeCall(string operationName, object[] inputs)
{
  Console.WriteLine("IParameterInspector.BeforeCall called for {0}.", operationName);
  return null;
}

#Region "IParameterInspector Members"
        Public Sub AfterCall(ByVal operationName As String, ByVal outputs() As Object, ByVal returnValue As Object, _
                             ByVal correlationState As Object) Implements IParameterInspector.AfterCall
            Console.WriteLine("IParameterInspector.AfterCall called for {0} with return value {1}.", _
                              operationName, returnValue.ToString())
        End Sub

        Public Function BeforeCall(ByVal operationName As String, ByVal inputs() As Object) As Object Implements _
        IParameterInspector.BeforeCall
            Console.WriteLine("IParameterInspector.BeforeCall called for {0}.", operationName)
            Return Nothing
        End Function

using System;
using System.Collections.Generic;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Configuration;
using System.ServiceModel.Description;
using System.ServiceModel.Dispatcher;
using System.Text;

namespace Microsoft.WCF.Documentation
{
  public class InspectorInserter : BehaviorExtensionElement, IServiceBehavior, IEndpointBehavior, IOperationBehavior
  {
    #region IServiceBehavior Members
    public void AddBindingParameters(
      ServiceDescription serviceDescription,
      ServiceHostBase serviceHostBase,
      System.Collections.ObjectModel.Collection<ServiceEndpoint> endpoints,
      BindingParameterCollection bindingParameters
    )
    { return; }

    public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
    {
      foreach (ChannelDispatcher chDisp in serviceHostBase.ChannelDispatchers)
      {
        foreach (EndpointDispatcher epDisp in chDisp.Endpoints)
        {
          epDisp.DispatchRuntime.MessageInspectors.Add(new Inspector());
          foreach (DispatchOperation op in epDisp.DispatchRuntime.Operations)
            op.ParameterInspectors.Add(new Inspector());
        }
      }
    }

    public void Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase){ return; }

    #endregion
    #region IEndpointBehavior Members
    public void AddBindingParameters(
      ServiceEndpoint endpoint, BindingParameterCollection bindingParameters
    ) { return; }

    public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
    {
      clientRuntime.MessageInspectors.Add(new Inspector());
      foreach (ClientOperation op in clientRuntime.Operations)
        op.ParameterInspectors.Add(new Inspector());
    }

    public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
    {
      endpointDispatcher.DispatchRuntime.MessageInspectors.Add(new Inspector());
      foreach (DispatchOperation op in endpointDispatcher.DispatchRuntime.Operations)
        op.ParameterInspectors.Add(new Inspector());
    }

    public void Validate(ServiceEndpoint endpoint){ return; }
    #endregion
    #region IOperationBehavior Members
    public void AddBindingParameters(
      OperationDescription operationDescription, BindingParameterCollection bindingParameters
    )
    { return; }

    public void ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation)
    {
      clientOperation.ParameterInspectors.Add(new Inspector());
    }

    public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation)
    {
      dispatchOperation.ParameterInspectors.Add(new Inspector());
    }

    public void Validate(OperationDescription operationDescription){ return; }

    #endregion

    public override Type BehaviorType
    {
      get { return typeof(InspectorInserter); }
    }

    protected override object CreateBehavior()
    { return new InspectorInserter(); }
  }
}

Imports System.ServiceModel
Imports System.ServiceModel.Channels
Imports System.ServiceModel.Configuration
Imports System.ServiceModel.Description
Imports System.ServiceModel.Dispatcher
Imports System.Text

Namespace Microsoft.WCF.Documentation
    Public Class InspectorInserter
        Inherits BehaviorExtensionElement
        Implements IServiceBehavior, IEndpointBehavior, IOperationBehavior
#Region "IServiceBehavior Members"
        Public Sub AddBindingParameters(ByVal serviceDescription As ServiceDescription, _
                       ByVal serviceHostBase As ServiceHostBase, ByVal endpoints As _
                       System.Collections.ObjectModel.Collection(Of ServiceEndpoint), _
                       ByVal bindingParameters As BindingParameterCollection) Implements IServiceBehavior.AddBindingParameters
            Return
        End Sub

        Public Sub ApplyDispatchBehavior(ByVal serviceDescription As ServiceDescription, _
                                         ByVal serviceHostBase As ServiceHostBase) Implements _
                                         IServiceBehavior.ApplyDispatchBehavior
            For Each chDisp As ChannelDispatcher In serviceHostBase.ChannelDispatchers
                For Each epDisp As EndpointDispatcher In chDisp.Endpoints
                    epDisp.DispatchRuntime.MessageInspectors.Add(New Inspector())
                    For Each op As DispatchOperation In epDisp.DispatchRuntime.Operations
                        op.ParameterInspectors.Add(New Inspector())
                    Next op
                Next epDisp
            Next chDisp
        End Sub

        Public Sub Validate(ByVal serviceDescription As ServiceDescription, ByVal serviceHostBase As ServiceHostBase) _
        Implements IServiceBehavior.Validate
            Return
        End Sub

#End Region
#Region "IEndpointBehavior Members"
        Public Sub AddBindingParameters(ByVal endpoint As ServiceEndpoint, ByVal bindingParameters _
                                        As BindingParameterCollection) Implements IEndpointBehavior.AddBindingParameters
            Return
        End Sub

        Public Sub ApplyClientBehavior(ByVal endpoint As ServiceEndpoint, ByVal clientRuntime As ClientRuntime) _
        Implements IEndpointBehavior.ApplyClientBehavior
            clientRuntime.MessageInspectors.Add(New Inspector())
            For Each op As ClientOperation In clientRuntime.Operations
                op.ParameterInspectors.Add(New Inspector())
            Next op
        End Sub

        Public Sub ApplyDispatchBehavior(ByVal endpoint As ServiceEndpoint, ByVal endpointDispatcher As _
                                         EndpointDispatcher) Implements IEndpointBehavior.ApplyDispatchBehavior
            endpointDispatcher.DispatchRuntime.MessageInspectors.Add(New Inspector())
            For Each op As DispatchOperation In endpointDispatcher.DispatchRuntime.Operations
                op.ParameterInspectors.Add(New Inspector())
            Next op
        End Sub

        Public Sub Validate(ByVal endpoint As ServiceEndpoint) Implements IEndpointBehavior.Validate
            Return
        End Sub
#End Region
#Region "IOperationBehavior Members"
        Public Sub AddBindingParameters(ByVal operationDescription As OperationDescription, _
                                        ByVal bindingParameters As BindingParameterCollection) Implements _
                                        IOperationBehavior.AddBindingParameters
            Return
        End Sub

        Public Sub ApplyClientBehavior(ByVal operationDescription As OperationDescription, ByVal _
                                       clientOperation As ClientOperation) Implements IOperationBehavior.ApplyClientBehavior
            clientOperation.ParameterInspectors.Add(New Inspector())
        End Sub

        Public Sub ApplyDispatchBehavior(ByVal operationDescription As OperationDescription, ByVal dispatchOperation As _
                                         DispatchOperation) Implements IOperationBehavior.ApplyDispatchBehavior
            dispatchOperation.ParameterInspectors.Add(New Inspector())
        End Sub

        Public Sub Validate(ByVal operationDescription As OperationDescription) Implements IOperationBehavior.Validate
            Return
        End Sub

#End Region

        Public Overrides ReadOnly Property BehaviorType() As Type
            Get
                Return GetType(InspectorInserter)
            End Get
        End Property

        Protected Overrides Function CreateBehavior() As Object
            Return New InspectorInserter()
        End Function
    End Class
End Namespace

  <client>
      <endpoint 
        address="http://localhost:8080/SampleService" 
        behaviorConfiguration="clientInspectorsAdded" 
        binding="wsHttpBinding"
        bindingConfiguration="WSHttpBinding_ISampleService" 
        contract="ISampleService"
        name="WSHttpBinding_ISampleService"
      >
      </endpoint>
  </client>
<behaviors>
  <endpointBehaviors>
    <behavior name="clientInspectorsAdded">
      <clientInterceptors />
    </behavior>
  </endpointBehaviors>
</behaviors>
<extensions>
  <behaviorExtensions>
    <add 
      name="clientInterceptors" 
      type="Microsoft.WCF.Documentation.InspectorInserter, HostApplication, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null"
  />
  </behaviorExtensions>
</extensions>

How to: Inspect or Modify Parameters

Inspecting or Modifying Parameters

Example

See also

Additional resources