wcf rest服务启用gzip压缩

    在IIS上添加gzip压缩已经不是什么新鲜事情了，但是如何在自host的wcf上对rest响应支持gzip压缩哪？

    乍一看这个命题还真的有点难，但是wcf框架本身相当强大，拥有众多的介入点，只要正确的介入binding和behavior就可以很简单的达到目的

准备Binding

     首先，因为需要修改输出结果的编码，那么不可避免的需要修改Binding，如果熟悉WCF的Binding模型的话，可以很容易的将传统的wsHttpBinding,webHttpBinding,netTcpBinding等分解，由于目标是rest服务，因此传输层使用http方式，即：HttpTransportBindingElement，而编码层则需要在原来的编码层基础上添加gzip压缩，因此需要嵌套原来的WebMessageEncodingBindingElement，并在原来的基础上添加gzip效果。

     然后就是Binding的拼装了，好吧，我不想把事件搞得太负责，直接用CustomBinding来组装：

using System;

using System.IO;

using System.IO.Compression;

using System.ServiceModel;

using System.ServiceModel.Channels;

using System.ServiceModel.Web;

using System.Xml;



namespace Zhenway.RestWithGZip

{

    public class ZhenwayWebHttpBinding

        : CustomBinding, IBindingRuntimePreferences

    {



        #region Ctors



        public ZhenwayWebHttpBinding()

            : base(GetBindingElements()) { }



        public ZhenwayWebHttpBinding(string configurationName)

            : base(GetBindingElements())

        {

            ApplyConfiguration(configurationName);

        }



        #endregion



        #region Methods



        private static BindingElementCollection GetBindingElements()

        {

            WebHttpBinding webHttpBinding;

            webHttpBinding = new WebHttpBinding();

            var collection = webHttpBinding.CreateBindingElements();

            var encodingBindingElement = collection.Find<MessageEncodingBindingElement>();

            var index = collection.IndexOf(encodingBindingElement);

            collection.RemoveAt(index);

            var wrapperBindingElement = new WrapperEncodingBindingElement(encodingBindingElement);

            collection.Insert(index, wrapperBindingElement);

            return collection;

        }



        private void ApplyConfiguration(string configurationName)

        {

            ZhenwayWebHttpBindingCollectionElement c = ZhenwayWebHttpBindingCollectionElement.GetBindingCollectionElement();

            ZhenwayWebHttpBindingElement element = c.Bindings[configurationName];

            if (element == null)

                throw new InvalidOperationException("Configuration[" + configurationName + "] not found.");

            element.ApplyConfiguration(this);

        }



        #endregion



        #region Properties



        private HttpTransportBindingElement httpTransportBindingElement { get { return Elements.Find<HttpTransportBindingElement>(); } }



        public bool AllowCookies

        {

            get { return httpTransportBindingElement.AllowCookies; }

            set { httpTransportBindingElement.AllowCookies = value; }

        }



        public long MaxBufferPoolSize

        {

            get { return httpTransportBindingElement.MaxBufferPoolSize; }

            set { httpTransportBindingElement.MaxBufferPoolSize = value; }

        }



        public int MaxBufferSize

        {

            get { return httpTransportBindingElement.MaxBufferSize; }

            set { httpTransportBindingElement.MaxBufferSize = value; }

        }



        public long MaxReceivedMessageSize

        {

            get { return httpTransportBindingElement.MaxReceivedMessageSize; }

            set { httpTransportBindingElement.MaxReceivedMessageSize = value; }

        }



        public XmlDictionaryReaderQuotas ReaderQuotas

        {

            get { return ((WrapperEncodingBindingElement)Elements.Find<MessageEncodingBindingElement>()).ReaderQuotas; }

            set

            {

                if (value == null)

                    throw new ArgumentNullException("value");

                value.CopyTo(((WrapperEncodingBindingElement)Elements.Find<MessageEncodingBindingElement>()).ReaderQuotas);

            }

        }



        public override string Scheme { get { return "http"; } }



        bool IBindingRuntimePreferences.ReceiveSynchronously

        {

            get { return false; }

        }



        public TransferMode TransferMode

        {

            get { return httpTransportBindingElement.TransferMode; }

            set { httpTransportBindingElement.TransferMode = value; }

        }



        #endregion



        #region Wrapper Classes



        private sealed class WrapperEncodingBindingElement

            : MessageEncodingBindingElement

        {

            private readonly WebMessageEncodingBindingElement m_bindingElement;

            public WrapperEncodingBindingElement(MessageEncodingBindingElement bindingElement)

            {

                this.m_bindingElement = (WebMessageEncodingBindingElement)bindingElement;

            }

            public override MessageEncoderFactory CreateMessageEncoderFactory()

            {

                return new WrapperMessageEncoderFactory(m_bindingElement.CreateMessageEncoderFactory());

            }

            public override MessageVersion MessageVersion

            {

                get { return this.m_bindingElement.MessageVersion; }

                set { this.m_bindingElement.MessageVersion = value; }

            }

            public override BindingElement Clone()

            {

                MessageEncodingBindingElement bindingElement = (MessageEncodingBindingElement)this.m_bindingElement.Clone();

                return new WrapperEncodingBindingElement(bindingElement);

            }

            public XmlDictionaryReaderQuotas ReaderQuotas

            {

                get { return m_bindingElement.ReaderQuotas; }

            }

            public override IChannelFactory<TChannel> BuildChannelFactory<TChannel>(BindingContext context)

            {

                context.BindingParameters.Add(this);

                return context.BuildInnerChannelFactory<TChannel>();

            }

            public override IChannelListener<TChannel> BuildChannelListener<TChannel>(BindingContext context)

            {

                context.BindingParameters.Add(this);

                return context.BuildInnerChannelListener<TChannel>();

            }

            public override bool CanBuildChannelFactory<TChannel>(BindingContext context)

            {

                context.BindingParameters.Add(this);

                return context.CanBuildInnerChannelFactory<TChannel>();

            }

            public override bool CanBuildChannelListener<TChannel>(BindingContext context)

            {

                context.BindingParameters.Add(this);

                return context.CanBuildInnerChannelListener<TChannel>();

            }

            public override T GetProperty<T>(BindingContext context)

            {

                if (context == null)

                {

                    throw new ArgumentNullException("context");

                }

                if (typeof(T) == typeof(XmlDictionaryReaderQuotas))

                {

                    return (T)(object)this.ReaderQuotas;

                }

                return base.GetProperty<T>(context);

            }

        }



        private sealed class WrapperMessageEncoderFactory

            : MessageEncoderFactory

        {

            private readonly MessageEncoderFactory m_inner;

            private readonly MessageEncoder m_encoder;

            public WrapperMessageEncoderFactory(MessageEncoderFactory factory)

            {

                this.m_inner = factory;

                this.m_encoder = new WrapperMessageEncoder(factory.Encoder);

            }

            public override MessageEncoder Encoder

            {

                get { return this.m_encoder; }

            }

            public override MessageVersion MessageVersion

            {

                get { return this.m_encoder.MessageVersion; }

            }

        }



        private sealed class WrapperMessageEncoder

            : MessageEncoder

        {

            private readonly MessageEncoder m_inner;



            public WrapperMessageEncoder(MessageEncoder encoder)

            {

                this.m_inner = encoder;

            }



            #region Overrides

            public override string ContentType

            {

                get { return this.m_inner.ContentType; }

            }

            public override string MediaType

            {

                get { return this.m_inner.MediaType; }

            }

            public override MessageVersion MessageVersion

            {

                get { return this.m_inner.MessageVersion; }

            }

            public override bool IsContentTypeSupported(string contentType)

            {

                return this.m_inner.IsContentTypeSupported(contentType);

            }

            public override T GetProperty<T>()

            {

                return this.m_inner.GetProperty<T>();

            }

            public override Message ReadMessage(ArraySegment<byte> buffer, BufferManager bufferManager, string contentType)

            {

                return this.m_inner.ReadMessage(buffer, bufferManager, contentType);

            }

            public override Message ReadMessage(Stream stream, int maxSizeOfHeaders, string contentType)

            {

                return this.m_inner.ReadMessage(stream, maxSizeOfHeaders, contentType);

            }

            public override ArraySegment<byte> WriteMessage(Message message, int maxMessageSize, BufferManager bufferManager, int messageOffset)

            {

                var c = WebOperationContext.Current;

                // 写Buffered消息

                ArraySegment<byte> buffer = this.m_inner.WriteMessage(message, maxMessageSize, bufferManager, messageOffset);

                if (c != null && message.Properties.ContainsKey("gzip"))

                    return CompressBuffer(buffer, bufferManager, messageOffset);

                return buffer;

            }

            public override void WriteMessage(Message message, Stream stream)

            {

                // 写Streaming消息

                var c = WebOperationContext.Current;

                if (c != null && message.Properties.ContainsKey("gzip"))

                {

                    using (var gz = new GZipStream(stream, CompressionMode.Compress, true))

                        this.m_inner.WriteMessage(message, gz);

                    stream.Flush();

                    return;

                }

                this.m_inner.WriteMessage(message, stream);

            }

            #endregion



            private static ArraySegment<byte> CompressBuffer(ArraySegment<byte> buffer, BufferManager bufferManager, int messageOffset)

            {

                // 压缩

                var ms = new MemoryStream(Math.Max(buffer.Count >> 1, 512));

                using (var gz = new GZipStream(ms, CompressionMode.Compress, true))

                    gz.Write(buffer.Array, messageOffset, buffer.Count);

                // 重新组织消息体

                byte[] bufferedBytes = bufferManager.TakeBuffer(messageOffset + (int)ms.Length);

                byte[] compressedBytes = ms.GetBuffer();

                Array.Copy(buffer.Array, 0, bufferedBytes, 0, messageOffset);

                Array.Copy(compressedBytes, 0, bufferedBytes, messageOffset, (int)ms.Length);

                bufferManager.ReturnBuffer(buffer.Array);

                return new ArraySegment<byte>(bufferedBytes, messageOffset, (int)ms.Length);

            }



        }



        #endregion



    }

}

    binding就准备好啦，不过这个binding只能用代码形式创建，而不能用配置形式创建，显然与wcf强大的配置功能有点不合拍，再加下binding的配置节支持：

using System;

using System.Configuration;

using System.ServiceModel;

using System.ServiceModel.Channels;

using System.ServiceModel.Configuration;

using System.Xml;



namespace Zhenway.RestWithGZip

{

    public class ZhenwayWebHttpBindingElement

        : StandardBindingElement

    {



        #region Fields

        private ConfigurationPropertyCollection m_properties;

        #endregion



        #region Ctors



        public ZhenwayWebHttpBindingElement(string name)

            : base(name) { }



        public ZhenwayWebHttpBindingElement()

            : this(null) { }



        #endregion



        #region ConfigurationProperties



        [ConfigurationProperty("allowCookies", DefaultValue = false)]

        public bool AllowCookies

        {

            get { return (bool)base["allowCookies"]; }

            set { base["allowCookies"] = value; }

        }



        [LongValidator(MinValue = 0L), ConfigurationProperty("maxBufferPoolSize", DefaultValue = 524288L)]

        public long MaxBufferPoolSize

        {

            get { return (long)base["maxBufferPoolSize"]; }

            set { base["maxBufferPoolSize"] = value; }

        }



        [ConfigurationProperty("maxBufferSize", DefaultValue = 65536), IntegerValidator(MinValue = 1)]

        public int MaxBufferSize

        {

            get { return (int)base["maxBufferSize"]; }

            set { base["maxBufferSize"] = value; }

        }



        [ConfigurationProperty("maxReceivedMessageSize", DefaultValue = 65536L), LongValidator(MinValue = 1L)]

        public long MaxReceivedMessageSize

        {

            get { return (long)base["maxReceivedMessageSize"]; }

            set { base["maxReceivedMessageSize"] = value; }

        }



        [ConfigurationProperty("readerQuotas")]

        public XmlDictionaryReaderQuotasElement ReaderQuotas

        {

            get { return (XmlDictionaryReaderQuotasElement)base["readerQuotas"]; }

        }



        [ConfigurationProperty("transferMode", DefaultValue = TransferMode.Buffered)]

        public TransferMode TransferMode

        {

            get { return (TransferMode)base["transferMode"]; }

            set { base["transferMode"] = value; }

        }



        #endregion



        #region Methods



        protected override Type BindingElementType

        {

            get { return typeof(ZhenwayWebHttpBinding); }

        }



        protected override ConfigurationPropertyCollection Properties

        {

            get

            {

                if (this.m_properties == null)

                {

                    ConfigurationPropertyCollection c = base.Properties;

                    c.Add(new ConfigurationProperty("allowCookies", typeof(bool), false, null, null, ConfigurationPropertyOptions.None));

                    c.Add(new ConfigurationProperty("maxBufferSize", typeof(int), 65536, null, new IntegerValidator(1, 2147483647, false), ConfigurationPropertyOptions.None));

                    c.Add(new ConfigurationProperty("maxBufferPoolSize", typeof(long), 524288L, null, new LongValidator(0L, 9223372036854775807L, false), ConfigurationPropertyOptions.None));

                    c.Add(new ConfigurationProperty("maxReceivedMessageSize", typeof(long), 65536L, null, new LongValidator(1L, 9223372036854775807L, false), ConfigurationPropertyOptions.None));

                    c.Add(new ConfigurationProperty("readerQuotas", typeof(XmlDictionaryReaderQuotasElement), null, null, null, ConfigurationPropertyOptions.None));

                    c.Add(new ConfigurationProperty("transferMode", typeof(TransferMode), TransferMode.Buffered, null, null, ConfigurationPropertyOptions.None));

                    this.m_properties = c;

                }

                return this.m_properties;

            }

        }



        protected override void InitializeFrom(Binding binding)

        {

            base.InitializeFrom(binding);

            ZhenwayWebHttpBinding zBinding = (ZhenwayWebHttpBinding)binding;

            this.MaxBufferSize = zBinding.MaxBufferSize;

            this.MaxBufferPoolSize = zBinding.MaxBufferPoolSize;

            this.MaxReceivedMessageSize = zBinding.MaxReceivedMessageSize;

            this.TransferMode = zBinding.TransferMode;

            this.AllowCookies = zBinding.AllowCookies;

            this.InitializeReaderQuotas(zBinding.ReaderQuotas);

        }



        internal void InitializeReaderQuotas(XmlDictionaryReaderQuotas readerQuotas)

        {

            if (readerQuotas == null)

            {

                throw new ArgumentNullException("readerQuotas");

            }

            this.ReaderQuotas.MaxDepth = readerQuotas.MaxDepth;

            this.ReaderQuotas.MaxStringContentLength = readerQuotas.MaxStringContentLength;

            this.ReaderQuotas.MaxArrayLength = readerQuotas.MaxArrayLength;

            this.ReaderQuotas.MaxBytesPerRead = readerQuotas.MaxBytesPerRead;

            this.ReaderQuotas.MaxNameTableCharCount = readerQuotas.MaxNameTableCharCount;

        }



        protected override void OnApplyConfiguration(Binding binding)

        {

            var zBinding = (ZhenwayWebHttpBinding)binding;

            zBinding.MaxBufferPoolSize = this.MaxBufferPoolSize;

            zBinding.MaxReceivedMessageSize = this.MaxReceivedMessageSize;

            zBinding.TransferMode = this.TransferMode;

            zBinding.AllowCookies = this.AllowCookies;

            PropertyInformationCollection propertyInformationCollection = base.ElementInformation.Properties;

            if (propertyInformationCollection["maxBufferSize"].ValueOrigin != PropertyValueOrigin.Default)

            {

                zBinding.MaxBufferSize = this.MaxBufferSize;

            }

            this.ApplyReaderQuotasConfiguration(zBinding.ReaderQuotas);

        }



        private void ApplyReaderQuotasConfiguration(XmlDictionaryReaderQuotas readerQuotas)

        {

            if (readerQuotas == null)

                throw new ArgumentNullException("readerQuotas");

            if (this.ReaderQuotas.MaxDepth != 0)

            {

                readerQuotas.MaxDepth = this.ReaderQuotas.MaxDepth;

            }

            if (this.ReaderQuotas.MaxStringContentLength != 0)

            {

                readerQuotas.MaxStringContentLength = this.ReaderQuotas.MaxStringContentLength;

            }

            if (this.ReaderQuotas.MaxArrayLength != 0)

            {

                readerQuotas.MaxArrayLength = this.ReaderQuotas.MaxArrayLength;

            }

            if (this.ReaderQuotas.MaxBytesPerRead != 0)

            {

                readerQuotas.MaxBytesPerRead = this.ReaderQuotas.MaxBytesPerRead;

            }

            if (this.ReaderQuotas.MaxNameTableCharCount != 0)

            {

                readerQuotas.MaxNameTableCharCount = this.ReaderQuotas.MaxNameTableCharCount;

            }

        }



        #endregion



    }

}

    还有配置节的入口：

using System;

using System.Configuration;

using System.ServiceModel.Channels;

using System.ServiceModel.Configuration;



namespace Zhenway.RestWithGZip

{

    public class ZhenwayWebHttpBindingCollectionElement

        : StandardBindingCollectionElement<ZhenwayWebHttpBinding, ZhenwayWebHttpBindingElement>

    {



        protected override Binding GetDefault()

        {

            return new ZhenwayWebHttpBinding();

        }



        internal static ZhenwayWebHttpBindingCollectionElement GetBindingCollectionElement()

        {

            BindingsSection bindingsSection = null;

            string text = "system.serviceModel/bindings";

                bindingsSection = (BindingsSection)ConfigurationManager.GetSection(text);

            BindingCollectionElement bindingCollectionElement = bindingsSection["zhenwayWebHttpBinding"];

            return (ZhenwayWebHttpBindingCollectionElement)bindingCollectionElement;

        }



    }

}

    这样binding相关的内容就全部准备好了。

准备Behavior

    binding虽然准备好了，不过，哪些接口的结果需要进行gzip压缩哪？毕竟gzip对于部分内容的压缩效果好，对于某些内容着完全没有效果，甚至还会变大。

    最好能有个标记，标了就用gzip，没标记就不压，这样就能基本顾及常规的使用

using System;

using System.IO;

using System.Net;

using System.ServiceModel.Channels;

using System.ServiceModel.Description;

using System.ServiceModel.Dispatcher;

using System.ServiceModel.Web;



namespace Zhenway.RestWithGZip

{

    [AttributeUsage(AttributeTargets.Method)]

    public class GZipAttribute

        : Attribute, IOperationBehavior

    {



        #region IOperationBehavior 成员



        public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation)

        {

            dispatchOperation.Formatter = new GZipFormatter(dispatchOperation.Formatter);

        }



        void IOperationBehavior.AddBindingParameters(OperationDescription operationDescription, System.ServiceModel.Channels.BindingParameterCollection bindingParameters) { }



        void IOperationBehavior.ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation) { }



        void IOperationBehavior.Validate(OperationDescription operationDescription) { }



        #endregion



        #region Subclass: OperationInvoker



        private sealed class GZipFormatter

            : IDispatchMessageFormatter

        {



            private readonly IDispatchMessageFormatter m_inner;



            public GZipFormatter(IDispatchMessageFormatter inner)

            {

                m_inner = inner;

            }



            #region IDispatchMessageFormatter 成员



            public void DeserializeRequest(Message message, object[] parameters)

            {

                m_inner.DeserializeRequest(message, parameters);

            }



            public Message SerializeReply(MessageVersion messageVersion, object[] parameters, object result)

            {

                var msg = m_inner.SerializeReply(messageVersion, parameters, result);

                var c = WebOperationContext.Current;

                if (c != null)

                {

                    var ae = c.IncomingRequest.Headers[HttpRequestHeader.AcceptEncoding];

                    if (ae != null || ae.IndexOf("gzip", StringComparison.OrdinalIgnoreCase) >= 0 &&

                        "gzip".Equals(c.OutgoingResponse.Headers[HttpResponseHeader.ContentEncoding], StringComparison.OrdinalIgnoreCase) &&

                        result != null)

                    {

                        msg.Properties["gzip"] = "1";

                        c.OutgoingResponse.Headers[HttpResponseHeader.ContentEncoding] = "gzip";

                    }

                }

                return msg;

            }



            #endregion

        }



        #endregion



    }

}

    这样就能很方便的使用啦。

来个示例

    契约：

using System;

using System.IO;

using System.ServiceModel;

using System.ServiceModel.Web;



namespace Zhenway.RestWithGZip

{

    [ServiceContract]

    public interface IService1

    {

        [GZip]

        [ContentType("text/plain")]

        [CacheControl(CacheControl.NoCache)]

        [WebGet(UriTemplate = "buffered/{value}/")]

        [OperationContract]

        string TestBufferedMessage(string value);

        [GZip]

        [ContentType("text/html")]

        [CacheControl(10)]

        [WebGet(UriTemplate = "streaming/{value}/")]

        [OperationContract]

        Stream TestStreamingMessage(string value);

    }

}

    实现：

using System;

using System.IO;



namespace Zhenway.RestWithGZip

{

    public class Service1 : IService1

    {

        public string TestBufferedMessage(string value)

        {

            return string.Format("You entered: {0}", value);

        }



        public Stream TestStreamingMessage(string value)

        {

            var s = string.Format("<p>You entered: {0}<p>", value);

            var ms = new MemoryStream();

            var sw = new StreamWriter(ms);

            sw.Write("<html><body>");

            for (int i = 0; i < 1000; i++)

            {

                sw.WriteLine(s);

            }

            sw.Write("</body></html>");

            sw.Flush();

            ms.Seek(0, SeekOrigin.Begin);

            return ms;

        }

    }

}

    配置：

<?xml version="1.0"?>

<configuration>

  <system.serviceModel>

    <extensions>

      <bindingExtensions>

        <add name="zhenwayWebHttpBinding" type="Zhenway.RestWithGZip.ZhenwayWebHttpBindingCollectionElement, Zhenway.RestWithGZip"/>

      </bindingExtensions>

    </extensions>

    <bindings>

      <zhenwayWebHttpBinding>

        <binding name="AllowCookies" allowCookies="true"/>

      </zhenwayWebHttpBinding>

    </bindings>

    <services>

      <service name="Zhenway.RestWithGZip.Service1">

        <host>

          <baseAddresses>

            <add baseAddress="http://localhost:8888/"/>

          </baseAddresses>

        </host>

        <endpoint address="" binding="zhenwayWebHttpBinding" bindingConfiguration="AllowCookies" contract="Zhenway.RestWithGZip.IService1" behaviorConfiguration="RestBehavior">

          <identity>

            <dns value="localhost"/>

          </identity>

        </endpoint>

      </service>

    </services>

    <behaviors>

      <serviceBehaviors>

        <behavior>

          <serviceMetadata httpGetEnabled="True"/>

          <serviceDebug includeExceptionDetailInFaults="False"/>

        </behavior>

      </serviceBehaviors>

      <endpointBehaviors>

        <behavior name="RestBehavior">

          <webHttp/>

        </behavior>

      </endpointBehaviors>

    </behaviors>

  </system.serviceModel>

  <startup>

    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>

  </startup>

</configuration>

    实际效果(Buffered方式)：

    实际效果(Streaming方式)： 

源代码下载：

/Files/vwxyzh/201202/RestWithGZip.zip