使用IParameterInspector, IOperationBehavior,Attribute(参数检查器、操作行为接口和标签)扩展WCF操作行为

开发环境： VS2008 SP1 WIN2008 SP2
WCF允许我们在端点Endpoint、消息message、操作Operation、参数Parameter中扩展WCF。本文简单介绍如何截获操作的参数来扩展WCF的操作。这种扩展需要在WCF的Contract契约上加标签来实现，不能算是真正的AOP，但是有些AOP的意思。
实现步骤：1、实现自己的参数检查器；2、将参数检查器放入要实现的操作行为；3、在操作Operation上加入标签attribute

1、实现自己的参数检查器，实现参数检查器，在调用操作前检查参数是否为17位数字，在调用操作后发送执行结果

    public class EntryIdInspector : IParameterInspector
    {
        public int intParamIndex
        {
            get;
            set;
        }
        string EntryIdFormat = @"\d{17}";
        
        public EntryIdInspector(): this(0){ }
        
        public EntryIdInspector(int intParamIndex)
        {
            this.intParamIndex = intParamIndex;
        }

        public object BeforeCall(string operationName, object[] inputs)
        {
            string strEntryId = inputs[this.intParamIndex] as string;
            if (!Regex.IsMatch(strEntryId, this.EntryIdFormat, RegexOptions.None))
            {
                
                MessageQueue mq = new MessageQueue(@".\private$\msgqueue");
                mq.Send( "Parameter is not valid when call " + operationName + " at " + DateTime.Now.ToLongDateString());
                throw new FaultException(
                    "Invalid Entry ID format. Required format: ##################");
            }
            return null;

        }
        public void AfterCall(string operationName, object[] outputs, object returnValue, object correlationState)
        {
            MessageQueue mq = new MessageQueue(@".\private$\msgqueue");
            string strResult = returnValue.ToString();
            mq.Send("Client call " + operationName + ":" + strResult + " at " + DateTime.Now.ToLongDateString());
                
        }
    }

2、将参数检查器放入要实现的操作行为

    public class EntryIdValidation : Attribute, IOperationBehavior
    {
        #region IOperationBehavior Members

        public void AddBindingParameters(OperationDescription operationDescription,
            BindingParameterCollection bindingParameters)
        {
        }

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

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

        public void Validate(OperationDescription operationDescription)
        {
        }

        #endregion
    }

3、在操作Operation上加入标签attribute，在操作契约中加上标签[EntryIdValidation]

    [ServiceContract]
    public interface IRelSrvContract
    {
        [EntryIdValidation]
        [OperationContract]
        bool Rel(string strEntryID);
    }