WCF中自定义消息编码器：压缩编码器的使用

通过抓包知道WCF在提交、返回数据的时候大多使用XML进行数据交互，如果返回DataTable那么这些数据将变得很大，通过查询找到一个对数据压缩的方法：

http://msdn.microsoft.com/zh-cn/library/ms751458(v=vs.110).aspx

新增项目GZipEncoder，GzipEncoder中增加三个文件 ：

GZipMessageEncoderFactory.cs

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Text;
using System.IO;
using System.IO.Compression;
using System.Runtime.Serialization;
using System.Runtime.InteropServices;
using System.Security;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Configuration;
using System.Xml;
using System.ServiceModel.Security;
using System.ServiceModel.Description;

namespace GZipEncoder
{
    //This class is used to create the custom encoder (GZipMessageEncoder)
    internal class GZipMessageEncoderFactory : MessageEncoderFactory
    {
        MessageEncoder encoder;

        //The GZip encoder wraps an inner encoder
        //We require a factory to be passed in that will create this inner encoder
        public GZipMessageEncoderFactory(MessageEncoderFactory messageEncoderFactory)
        {
            if (messageEncoderFactory == null)
                throw new ArgumentNullException("messageEncoderFactory", "A valid message encoder factory must be passed to the GZipEncoder");
            encoder = new GZipMessageEncoder(messageEncoderFactory.Encoder);

        }

        //The service framework uses this property to obtain an encoder from this encoder factory
        public override MessageEncoder Encoder
        {
            get { return encoder; }
        }

        public override MessageVersion MessageVersion
        {
            get { return encoder.MessageVersion; }
        }

        //This is the actual GZip encoder
        class GZipMessageEncoder : MessageEncoder
        {
            static string GZipContentType = "application/x-gzip";

            //This implementation wraps an inner encoder that actually converts a WCF Message
            //into textual XML, binary XML or some other format. This implementation then compresses the results.
            //The opposite happens when reading messages.
            //This member stores this inner encoder.
            MessageEncoder innerEncoder;

            //We require an inner encoder to be supplied (see comment above)
            internal GZipMessageEncoder(MessageEncoder messageEncoder)
                : base()
            {
                if (messageEncoder == null)
                    throw new ArgumentNullException("messageEncoder", "A valid message encoder must be passed to the GZipEncoder");
                innerEncoder = messageEncoder;
            }

            //public override string CharSet
            //{
            //    get { return ""; }
            //}

            public override string ContentType
            {
                get { return GZipContentType; }
            }

            public override string MediaType
            {
                get { return GZipContentType; }
            }

            //SOAP version to use - we delegate to the inner encoder for this
            public override MessageVersion MessageVersion
            {
                get { return innerEncoder.MessageVersion; }
            }

            //Helper method to compress an array of bytes
            static ArraySegment<byte> CompressBuffer(ArraySegment<byte> buffer, BufferManager bufferManager, int messageOffset)
            {
                MemoryStream memoryStream = new MemoryStream();
                memoryStream.Write(buffer.Array, 0, messageOffset);

                using (GZipStream gzStream = new GZipStream(memoryStream, CompressionMode.Compress, true))
                {
                    gzStream.Write(buffer.Array, messageOffset, buffer.Count);
                }

                byte[] compressedBytes = memoryStream.ToArray();
                byte[] bufferedBytes = bufferManager.TakeBuffer(compressedBytes.Length);

                Array.Copy(compressedBytes, 0, bufferedBytes, 0, compressedBytes.Length);

                bufferManager.ReturnBuffer(buffer.Array);
                ArraySegment<byte> byteArray = new ArraySegment<byte>(bufferedBytes, messageOffset, bufferedBytes.Length - messageOffset);

                return byteArray;
            }

            //Helper method to decompress an array of bytes
            static ArraySegment<byte> DecompressBuffer(ArraySegment<byte> buffer, BufferManager bufferManager)
            {
                MemoryStream memoryStream = new MemoryStream(buffer.Array, buffer.Offset, buffer.Count - buffer.Offset);
                MemoryStream decompressedStream = new MemoryStream();
                int totalRead = 0;
                int blockSize = 1024;
                byte[] tempBuffer = bufferManager.TakeBuffer(blockSize);
                using (GZipStream gzStream = new GZipStream(memoryStream, CompressionMode.Decompress))
                {
                    while (true)
                    {
                        int bytesRead = gzStream.Read(tempBuffer, 0, blockSize);
                        if (bytesRead == 0)
                            break;
                        decompressedStream.Write(tempBuffer, 0, bytesRead);
                        totalRead += bytesRead;
                    }
                }
                bufferManager.ReturnBuffer(tempBuffer);

                byte[] decompressedBytes = decompressedStream.ToArray();
                byte[] bufferManagerBuffer = bufferManager.TakeBuffer(decompressedBytes.Length + buffer.Offset);
                Array.Copy(buffer.Array, 0, bufferManagerBuffer, 0, buffer.Offset);
                Array.Copy(decompressedBytes, 0, bufferManagerBuffer, buffer.Offset, decompressedBytes.Length);

                ArraySegment<byte> byteArray = new ArraySegment<byte>(bufferManagerBuffer, buffer.Offset, decompressedBytes.Length);
                bufferManager.ReturnBuffer(buffer.Array);

                return byteArray;
            }

            //One of the two main entry points into the encoder. Called by WCF to decode a buffered byte array into a Message.
            public override Message ReadMessage(ArraySegment<byte> buffer, BufferManager bufferManager, string contentType)
            {
                //Decompress the buffer
                ArraySegment<byte> decompressedBuffer = DecompressBuffer(buffer, bufferManager);
                //Use the inner encoder to decode the decompressed buffer
                Message returnMessage = innerEncoder.ReadMessage(decompressedBuffer, bufferManager);
                returnMessage.Properties.Encoder = this;
                return returnMessage;
            }

            //One of the two main entry points into the encoder. Called by WCF to encode a Message into a buffered byte array.
            public override ArraySegment<byte> WriteMessage(Message message, int maxMessageSize, BufferManager bufferManager, int messageOffset)
            {
                //Use the inner encoder to encode a Message into a buffered byte array
                ArraySegment<byte> buffer = innerEncoder.WriteMessage(message, maxMessageSize, bufferManager, messageOffset);
                //Compress the resulting byte array
                return CompressBuffer(buffer, bufferManager, messageOffset);
            }

            public override Message ReadMessage(System.IO.Stream stream, int maxSizeOfHeaders, string contentType)
            {
                GZipStream gzStream = new GZipStream(stream, CompressionMode.Decompress, true);
                return innerEncoder.ReadMessage(gzStream, maxSizeOfHeaders);
            }

            public override void WriteMessage(Message message, System.IO.Stream stream)
            {
                using (GZipStream gzStream = new GZipStream(stream, CompressionMode.Compress, true))
                {
                    innerEncoder.WriteMessage(message, gzStream);
                }

                // innerEncoder.WriteMessage(message, gzStream) depends on that it can flush data by flushing
                // the stream passed in, but the implementation of GZipStream.Flush will not flush underlying
                // stream, so we need to flush here.
                stream.Flush();
            }
        }
    }
}

　　GZipMessageEncodingBindingElement.cs

using System;
using System.Xml;
using System.ServiceModel;
using System.Configuration;
using System.ServiceModel.Channels;
using System.ServiceModel.Configuration;
using System.ServiceModel.Description;

namespace GZipEncoder
{
    // This is constants for GZip message encoding policy.
    static class GZipMessageEncodingPolicyConstants
    {
        public const string GZipEncodingName = "GZipEncoding";
        public const string GZipEncodingNamespace = "http://schemas.microsoft.com/ws/06/2004/mspolicy/netgzip1";
        public const string GZipEncodingPrefix = "gzip";
    }

    //This is the binding element that, when plugged into a custom binding, will enable the GZip encoder
    public sealed class GZipMessageEncodingBindingElement
                        : MessageEncodingBindingElement //BindingElement
                        , IPolicyExportExtension
    {

        //We will use an inner binding element to store information required for the inner encoder
        MessageEncodingBindingElement innerBindingElement;

        //By default, use the default text encoder as the inner encoder
        public GZipMessageEncodingBindingElement()
            : this(new TextMessageEncodingBindingElement()) { }

        public GZipMessageEncodingBindingElement(MessageEncodingBindingElement messageEncoderBindingElement)
        {
            this.innerBindingElement = messageEncoderBindingElement;
        }

        public MessageEncodingBindingElement InnerMessageEncodingBindingElement
        {
            get { return innerBindingElement; }
            set { innerBindingElement = value; }
        }

        //Main entry point into the encoder binding element. Called by WCF to get the factory that will create the
        //message encoder
        public override MessageEncoderFactory CreateMessageEncoderFactory()
        {
            return new GZipMessageEncoderFactory(innerBindingElement.CreateMessageEncoderFactory());
        }

        public override MessageVersion MessageVersion
        {
            get { return innerBindingElement.MessageVersion; }
            set { innerBindingElement.MessageVersion = value; }
        }

        public override BindingElement Clone()
        {
            return new GZipMessageEncodingBindingElement(this.innerBindingElement);
        }

        public override T GetProperty<T>(BindingContext context)
        {
            if (typeof(T) == typeof(XmlDictionaryReaderQuotas))
            {
                return innerBindingElement.GetProperty<T>(context);
            }
            else
            {
                return base.GetProperty<T>(context);
            }
        }

        public override IChannelFactory<TChannel> BuildChannelFactory<TChannel>(BindingContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");

            context.BindingParameters.Add(this);
            return context.BuildInnerChannelFactory<TChannel>();
        }

        public override IChannelListener<TChannel> BuildChannelListener<TChannel>(BindingContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");

            context.BindingParameters.Add(this);
            return context.BuildInnerChannelListener<TChannel>();
        }

        public override bool CanBuildChannelListener<TChannel>(BindingContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");

            context.BindingParameters.Add(this);
            return context.CanBuildInnerChannelListener<TChannel>();
        }

        void IPolicyExportExtension.ExportPolicy(MetadataExporter exporter, PolicyConversionContext policyContext)
        {
            if (policyContext == null)
            {
                throw new ArgumentNullException("policyContext");
            }
            XmlDocument document = new XmlDocument();
            policyContext.GetBindingAssertions().Add(document.CreateElement(
                GZipMessageEncodingPolicyConstants.GZipEncodingPrefix,
                GZipMessageEncodingPolicyConstants.GZipEncodingName,
                GZipMessageEncodingPolicyConstants.GZipEncodingNamespace));
        }
    }

    //This class is necessary to be able to plug in the GZip encoder binding element through
    //a configuration file
    public class GZipMessageEncodingElement : BindingElementExtensionElement
    {
        public GZipMessageEncodingElement()
        {
        }

        //Called by the WCF to discover the type of binding element this config section enables
        public override Type BindingElementType
        {
            get { return typeof(GZipMessageEncodingBindingElement); }
        }

        //The only property we need to configure for our binding element is the type of
        //inner encoder to use. Here, we support text and binary.
        [ConfigurationProperty("innerMessageEncoding", DefaultValue = "textMessageEncoding")]
        public string InnerMessageEncoding
        {
            get { return (string)base["innerMessageEncoding"]; }
            set { base["innerMessageEncoding"] = value; }
        }

        //Called by the WCF to apply the configuration settings (the property above) to the binding element
        public override void ApplyConfiguration(BindingElement bindingElement)
        {
            GZipMessageEncodingBindingElement binding = (GZipMessageEncodingBindingElement)bindingElement;
            PropertyInformationCollection propertyInfo = this.ElementInformation.Properties;
            if (propertyInfo["innerMessageEncoding"].ValueOrigin != PropertyValueOrigin.Default)
            {
                switch (this.InnerMessageEncoding)
                {
                    case "textMessageEncoding":
                        binding.InnerMessageEncodingBindingElement = new TextMessageEncodingBindingElement();
                        break;
                    case "binaryMessageEncoding":
                        binding.InnerMessageEncodingBindingElement = new BinaryMessageEncodingBindingElement();
                        break;
                }
            }
        }

        //Called by the WCF to create the binding element
        protected override BindingElement CreateBindingElement()
        {
            GZipMessageEncodingBindingElement bindingElement = new GZipMessageEncodingBindingElement();
            this.ApplyConfiguration(bindingElement);
            return bindingElement;
        }
    }
}

　　GZipMessageEncodingBindingElementImporter.cs

using System;
using System.Xml;
using System.ServiceModel.Description;
using System.Xml.Schema;
using System.Collections.ObjectModel;
using System.Collections.Generic;
using System.Text;

namespace GZipEncoder
{
    public class GZipMessageEncodingBindingElementImporter : IPolicyImportExtension
    {
        public GZipMessageEncodingBindingElementImporter()
        {
        }

        void IPolicyImportExtension.ImportPolicy(MetadataImporter importer, PolicyConversionContext context)
        {
            if (importer == null)
            {
                throw new ArgumentNullException("importer");
            }

            if (context == null)
            {
                throw new ArgumentNullException("context");
            }

            ICollection<XmlElement> assertions = context.GetBindingAssertions();
            foreach (XmlElement assertion in assertions)
            {
                if ((assertion.NamespaceURI == GZipMessageEncodingPolicyConstants.GZipEncodingNamespace) &&
                    (assertion.LocalName == GZipMessageEncodingPolicyConstants.GZipEncodingName)
                    )
                {
                    assertions.Remove(assertion);
                    context.BindingElements.Add(new GZipMessageEncodingBindingElement());
                    break;
                }
            }
        }
    }
}

　　WCF Server 和 Client 都引用项目 GZipEncoder，然后修改config文件

Server web.config 中增加：

<?xml version="1.0" encoding="utf-8"?>
<configuration>

  <appSettings>
    <!-- 省略  -->
  </appSettings>

  <system.web>
    <compilation debug="true" targetFramework="4.0" />
    <customErrors mode="Off"/>
  </system.web>

  <system.serviceModel>

    <!-- GZipEncoder 加密部分 Begin -->
    <services><!-- name:命名空间.类名 -->
      <service name="WcfService.action">
        <endpoint address=""
                  binding="customBinding" bindingConfiguration="BufferedHttpSampleServer"
                  bindingName="BufferedHttpSampleServer"
                  contract="WcfService.Iaction" />
      </service>
    </services><!-- 注册 gzipMessageEncoding  -->
    <extensions>
      <bindingElementExtensions>
        <add name="gzipMessageEncoding"
             type="GZipEncoder.GZipMessageEncodingElement, GZipEncoder, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
      </bindingElementExtensions>
    </extensions>
    <bindings>
      <customBinding>
        <binding name="BufferedHttpSampleServer"><!-- 处理程序映射 -->
          <gzipMessageEncoding innerMessageEncoding="textMessageEncoding" />
          <httpTransport hostNameComparisonMode="StrongWildcard"
                         manualAddressing="False"
                         maxReceivedMessageSize="65536"
                         authenticationScheme="Anonymous"
                         bypassProxyOnLocal="False"
                         realm=""
                         useDefaultWebProxy="True" />
        </binding>
      </customBinding>
    </bindings>
    <!-- GZipEncoder 加密部分 End -->

    <behaviors>
      <serviceBehaviors>
        <behavior>
          <!-- 为避免泄漏元数据信息，请在部署前将以下值设置为 false 并删除上面的元数据终结点 -->
          <serviceMetadata httpGetEnabled="true"/>
          <!-- 要接收故障异常详细信息以进行调试，请将以下值设置为 true。在部署前设置为 false 以避免泄漏异常信息 -->
          <serviceDebug includeExceptionDetailInFaults="false"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />

  </system.serviceModel>

 <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
 </system.webServer>

</configuration>

　　客户端的app.config 配置：

<?xml version="1.0"?>
<configuration>

  <startup useLegacyV2RuntimeActivationPolicy="true">
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
    <supportedRuntime version="v2.0.50727"/>
  </startup>

  <system.serviceModel>
    <bindings>
      <customBinding>
        <binding name="WSHttpBinding_SwfBuilderService">
          <gzipMessageEncoding innerMessageEncoding="textMessageEncoding" />
          <httpTransport manualAddressing="false" authenticationScheme="Anonymous"
            bypassProxyOnLocal="false" hostNameComparisonMode="StrongWildcard"
            proxyAuthenticationScheme="Anonymous" realm="" useDefaultWebProxy="true" />
        </binding>
      </customBinding>
    </bindings>
    <client>

      <endpoint address="http://192.168.1.212/action.svc" binding="customBinding"
              bindingConfiguration="WSHttpBinding_SwfBuilderService"
              contract="WcfService.Iaction"
              name="WSHttpBinding_SwfBuilderService">
      </endpoint>
      <metadata>
        <policyImporters>
          <extension type="GZipEncoder.GZipMessageEncodingBindingElementImporter, GZipEncoder, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
        </policyImporters>
      </metadata>

    </client>

    <!-- gzip 扩展 -->
    <extensions>
      <bindingElementExtensions>
        <add name="gzipMessageEncoding" type="GZipEncoder.GZipMessageEncodingElement, GZipEncoder, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
      </bindingElementExtensions>
    </extensions>

  </system.serviceModel>

</configuration>

　　这样就完成了WCF的数据压缩，其他代码都不用动，直接可以使用

通过抓包看到Send和Recv的数据都为 application/x-gzip 格式

另外出现第一次调用WCF很慢的解决方法是将 useDefaultWebProxy 这个属性改成false，不让它找代理。这样就会在程序第一次调用WCF的时候快很多。