使用 NetDataContractSerializer 共享类型

在上一章节《WCF可序列化方式》 提到了NetDataContractSerializer 适用于客户端与服务端共享类型信息，支持支持类型不变性。 但并没有提供现成的特性，所以无法使用对数据契约进行标记的方式来达到使用NetDataContractSerializer的目的，必须通过自定制开发，才能对操作契约进行标注。

1. NetDataContractFormatAttribute特性；

    public class NetDataContractFormatAttribute : Attribute, IOperationBehavior
    {
        public void AddBindingParameters(OperationDescription operationDescription, BindingParameterCollection bindingParameters)
        {
            
        }

        public void ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation)
        {
            ReplaceDataContractSerializerOperationBehavior(operationDescription);
        }

        public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation)
        {
            ReplaceDataContractSerializerOperationBehavior(operationDescription);
        }

        public void Validate(OperationDescription operationDescription)
        {
            
        }

        public static void ReplaceDataContractSerializerOperationBehavior(OperationDescription description)
        {
            DataContractSerializerOperationBehavior dcs = description.Behaviors.Find<DataContractSerializerOperationBehavior>();
            
            if (dcs != null)
            {
                description.Behaviors.Remove(dcs);
            }
            description.Behaviors.Add(new NetDataContractSerializerOperationBehavior(description));
        }
    }

2. NetDataContractSerializerOperationBehavior 行为；

    public class NetDataContractSerializerOperationBehavior : DataContractSerializerOperationBehavior
    {
        private static NetDataContractSerializer serializer = new NetDataContractSerializer();

        public NetDataContractSerializerOperationBehavior(OperationDescription operationDescription)
            : base(operationDescription)
        {

        }

        public override XmlObjectSerializer CreateSerializer(Type type, string name, string ns, IList<Type> knownTypes)
        {
            return NetDataContractSerializerOperationBehavior.serializer;
        }

        public override XmlObjectSerializer CreateSerializer(Type type, XmlDictionaryString name, XmlDictionaryString ns, IList<Type> knownTypes)
        {
            return NetDataContractSerializerOperationBehavior.serializer;
        }
    }

3. 将特性标记在契约中；

    [ServiceContract(CallbackContract = typeof(IStockServiceCallback))]
    public interface IStockService
    {        
        [OperationContract]
        double GetPrice(string ticker);

        [OperationContract(IsOneWay = true)]
        void RegisterForUpdate(string ticker);

        [OperationContract]
        [NetDataContractFormat]
        StockPrice GetStockPrice(string ticker);
    }