聚焦WCF行为的扩展-技术开发专区

聚焦WCF行为的扩展

作者：IT168 张逸编辑：胡铭娅 2009-03-03 09:39 来源：IT168�

特别注意的是<extensions>下的 type值，必须是类型的full name。第一个逗点前的内容为完整的类型名（包括命名空间），第二部分为完整的命名空间。Version，Culture以及 PublicKeyToken也是缺一不可的。每个逗点后必须保留一个空格，否则无法正确添加扩展行为的配置。这与反射有关，但太容易让人忽略这一小细节。希望微软能在后来的版本中修订这个瑕疵。

3、在行为扩展的适当方法中，需要添加参数检查、消息检查或操作调用程序的扩展。这之间存在一定的对应关系。对于参数检查，我们需要在IOperationBehavior接口类型中的ApplyClientBehavior()以及ApplyDispatchBehavior()中添加。例如对于之前的CalculatorParameterInspector，我们可以定义一个类CalculatorParameterValidation：

public class CalculatorParameterValidation:Attribute, IOperationBehavior
{
        #region IOperationBehavior Members
        public void AddBindingParameters(OperationDescription operationDescription,
            BindingParameterCollection bindingParameters)
        {
        }

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

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

        public void Validate(OperationDescription operationDescription)
        {
        }
        #endregion
}

如果检查器与扩展行为在职责上没有分离的必要，一个更好的方法是定义一个类同时实现IParameterInspector和IOperationBehavior接口，例如：

public class CalculatorParameterValidation:Attribute, IParameterInspector, IOperationBehavior
{
        #region IParameterInspector Members
        public void BeforeCall(string operationName, object[] inputs)
        {
            int x = inputs[0] as int;
            int y = inputs[1] as int;
            if (x <0 || y < 0)
            {
               throw new FaultException("The number can not be less than zero.");
            }
            return null;
        }
        public void AfterCall(string operationName, object[] outputs, object returnValue, object correlationState)
        {
            //empty;
        }
        #endregion

        #region IOperationBehavior Members
        public void AddBindingParameters(OperationDescription operationDescription,
            BindingParameterCollection bindingParameters)
        {
        }

        public void ApplyClientBehavior(OperationDescription operationDescription,
            ClientOperation clientOperation)
        {
            CalculatorParameterInspector inspector = new CalculatorParameterInspector();
            clientOperation.ParameterInspectors.Add(thisinspector);
        }

        public void ApplyDispatchBehavior(OperationDescription operationDescription,
            DispatchOperation dispatchOperation)
        {
            CalculatorParameterInspector inspector = new CalculatorParameterInspector();
            dispatchOperation.ParameterInspectors.Add(thisinspector);
        }

        public void Validate(OperationDescription operationDescription)
        {
        }
        #endregion
}

操作调用程序虽然通过IOperationBehavior进行关联，但确是通过DispatchOperation的Invoker属性。假定我们已经定义了一个实现IOperationInvoker的类MyOperationInvoker，则关联的方法为：

public class MyOperationInvokerBehavior : Attribute, IOperationBehavior
    {
        #region IOperationBehavior Members
        public void AddBindingParameters(OperationDescription operationDescription,
            BindingParameterCollection bindingParameters)
        {
        }
        public void ApplyClientBehavior(OperationDescription operationDescription,
            ClientOperation clientOperation)
        {
        }
        public void ApplyDispatchBehavior(OperationDescription operationDescription,
            DispatchOperation dispatchOperation)
        {
            dispatchOperation.Invoker = new MyOperationInvoker(dispatchOperation.Invoker);
        }
        public void Validate(OperationDescription operationDescription)
        {
        }
        #endregion
    }

第1页：聚焦WCF行为的扩展第2页：四种类型的行为第3页：调用程序的扩展第4页：添加MessageInspectors

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