wcf自定义绑定

一，创建自定义绑定

有时候我们需要创建自己的绑定，这在很多情况下不是出于特殊的安全要求和使用的传输协议。为了创建自定义的绑定，需要建立一组绑定元素。绑定元素是由System.ServiceModel.Channels.BindingElement派生而来的。

代码1，使用HTTP传输协议和Binary编码格式的自定义绑定：

  <bindings>
      <customBinding>
        <binding name="binHttp">
          <binaryMessageEncoding />
          <httpTransport />
        </binding>
      </customBinding>
   </bindings>

除了用配置方式创建一个自定义绑定，也可以采用编程方式。

代码2，用编程方式配置一个自定义绑定：

    class Program
    {
        static void Main(string[] args)
        {
            CustomBinding binding = new CustomBinding();
            binding.Elements.Add(new BinaryMessageEncodingBindingElement());
            binding.Elements.Add(new HttpTransportBindingElement());

            ServiceHost host = new ServiceHost(typeof(CarRentalService));
            ServiceEndpoint serviceEndpoint =
                host.AddServiceEndpoint(typeof(ICarRentalService),
                    binding,
                    "http://localhost:8080/CarRentalService");

            try
            {
                host.Open();

                Console.WriteLine("The car rental service is up and listening on the following addresses:");
                foreach (var item in host.Description.Endpoints)
                {
                    Console.WriteLine("> [{0}] {1}", item.Binding.Name, item.Address.Uri.ToString());
                }
                Console.ReadLine();

                host.Close();
            }
            catch (CommunicationException ex)
            {
                host.Abort();
                Console.WriteLine(ex);
            }
            catch (TimeoutException ex)
            {
                host.Abort();
                Console.WriteLine(ex);
            }
            catch (Exception ex)
            {
                host.Abort();
                Console.WriteLine(ex);
            }
        }
    }

二，重用自定义绑定

有时，可能需要创建一个能够重复用于不同解决方案的自定义绑定。由于每个绑定都派生于System.ServiceModel.Channels.Binding这个抽象基类，我们只需建立自己的绑定类，并实现CreateBindingElement方法即可实现此目的。

代码1，由基类Binding创建一个可重用的自定义绑定：

    public class NetTcpTextBinding : Binding
    {
        private TcpTransportBindingElement transport;
        private TextMessageEncodingBindingElement encoding;
        public NetTcpTextBinding()
            : base()
        {
            this.Initialize();
        }
        public override BindingElementCollection CreateBindingElements()
        {
            BindingElementCollection elements = new BindingElementCollection();
            elements.Add(this.encoding);
            elements.Add(this.transport);
            return elements;
        }
        public override string Scheme
        {
            get { return this.transport.Scheme; }
        }
        private void Initialize()
        {
            this.transport = new TcpTransportBindingElement();
            this.encoding = new TextMessageEncodingBindingElement();
        }
    }

代码2，使用NetTcpTextBing绑定：

      NetTcpTextBinding binding = new NetTcpTextBinding();

      ServiceHost host = new ServiceHost(typeof(Service1));
      host.AddServiceEndpoint(typeof(IService1),
                binding,
                "net.tcp://localhost:10101/IService");

      host.Open();

如果需要通过配置文件使用自定义绑定，必须先扩展BindingCollectionElement抽象基类，然后再实现需要的方法。
代码3，实现NetTcpTextBindingCollectionElement:

namespace ConsoleApplication1
{
    public class NetTcpTextBindingCollectionElement : BindingCollectionElement
    {
        public override Type BindingType
        {
            get { return typeof(NetTcpTextBinding); }
        }

        public override ReadOnlyCollection<IBindingConfigurationElement>ConfiguredBindings
        {
            get
            {
                return new ReadOnlyCollection<IBindingConfigurationElement>(new List<IBindingConfigurationElement>());
            }
        }

        public override bool ContainsKey(string name)
        {
            throw new NotImplementedException();
        }

        protected override Binding GetDefault()
        {
            return new NetTcpTextBinding();
        }

        protected override bool TryAdd(string name, Binding binding, Configuration config)
        {
            throw new NotImplementedException();
        }
    }
}

现在，如果要在配置文件中使用自定义绑定NetTcpTextBinding，就必须用绑定扩展(<bindingExtensions>)配置NetTcpTextBindingCollectionElement元素。总之，如果要在配置文件中使用自定义绑定，就需要先进行定义。
代码4，在配置文件中使用自定义绑定NetTcpTextBinding：

  <system.serviceModel>
    <services>
      <service name="WcfServiceLibrary2.Service1">
        <endpoint address="net.tcp://localhost:10101/IService"
                  binding="netTcpTextBinding"
                  contract="WcfServiceLibrary2.IService1">
        </endpoint>
      </service>
    </services>
    <extensions>
      <bindingExtensions>
        <add name="netTcpTextBinding" type="ConsoleApplication1.NetTcpTextBindingCollectionElement, ConsoleApplication1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
      </bindingExtensions>
    </extensions>
  </system.serviceModel>

2013-03-30