WCF進階：將消息正文Base64編碼

大家好，很久沒有寫博文了，平時也是在用WCF做著項目，但不寫文，總是感覺對技術的把握不夠清楚全面。同時更主要的是和大家缺少很多溝通，有愧疚感呀。好了，閑話少敘，從今天起，我將推出WCF進階系列博文。和大家一起來繼續學習WCF。歡迎板磚！

WCF有一套標準的安全機制，但使用過的朋友都清楚，這些機制在編程和配置上都非常麻煩，重要的是還需要證書，這也不太容易部署，本文講述如何通過自定義Formatter將消息正文Base64編碼傳輸，雖然安全級別不是太高，但也能夠防止消息正文已明文形式傳輸。保護消息的秘密性。而且使用起來非常方便。通過學習本文，您能了解如下內容：1) 如何自定義消息記錄 2) 如何修改消息 3) 如何實現自定義編碼器。在WCF中消息是在通道堆棧中傳遞的，每個通道都可以對消息進行加工處理，上一個通道的輸出為下一個通道的輸入，而在消息通道中，WCF還開放很多Inspector,比如MessageInspector和ParamterInspector，通過這些攔截器，我們能實現自定義的消息記錄和修改。WCF還提供了自定義Formatter的接口來實現自定義的編碼器。我們就是利用WCF的上述接口來自定義編碼，將消息正文編碼為Base64的字符串，并且通過自定義的MessageInspector來記錄消息內容。

先看一下如何實現自定義MessageInspector,在WCF中提供了兩個接口: IClientMessageInspector和IDispatchMessageInspector，分別用于截取客戶端消息和服務端消息。這兩個接口的定義如下：

public interface IClientMessageInspector

{

// Methods

void AfterReceiveReply(ref Message reply, object correlationState);

object BeforeSendRequest(ref Message request, IClientChannel channel);

}

public interface IDispatchMessageInspector

{

// Methods

object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext);

void BeforeSendReply(ref Message reply, object correlationState);

}

實現了上述兩個接口的類即是自定義的MessageInspector。客戶端ClientRuntime對象和服務端的DispatchRumtime對象中管理中MessageInspectors集合，我們將自定義的MessageInspector實例化對象添加到集合中，MessageInspector即可生效。這個過程需要實現自定義的IEndpointBehavior。該接口的定義為：

public interface IEndpointBehavior

{

// Methods

void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters);

void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime);

void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher);

void Validate(ServiceEndpoint endpoint);

}

下面有兩個個代碼片段，分別實現了自定義MessageInspector和EndpointBehavior

1 . 自定義的MessageInspector:

代碼

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel.Dispatcher;

namespace RobinLib
{
    public class MessageInspector : IClientMessageInspector,IDispatchMessageInspector
    {
        #region IClientMessageInspector 成員

        public void AfterReceiveReply(ref System.ServiceModel.Channels.Message reply, object correlationState)
        {
            Console.WriteLine(reply.ToString());
        }

        public object BeforeSendRequest(ref System.ServiceModel.Channels.Message request, System.ServiceModel.IClientChannel channel)
        {
            Console.WriteLine(request.ToString());
            return null;
        }

        #endregion

        #region IDispatchMessageInspector 成員

        public object AfterReceiveRequest(ref System.ServiceModel.Channels.Message request, System.ServiceModel.IClientChannel channel, System.ServiceModel.InstanceContext instanceContext)
        {
            Console.WriteLine(request.ToString());
            return null;
        }

        public void BeforeSendReply(ref System.ServiceModel.Channels.Message reply, object correlationState)
        {
            Console.WriteLine(reply.ToString());
        }

        #endregion
    }
}

2 . 用于自定義消息記錄的自定義EndpointBehavior

代碼

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel.Description;
using System.ServiceModel.Dispatcher;

namespace RobinLib
{
    public class OutputMessageBehavior : IEndpointBehavior
    {

        #region IEndpointBehavior 成員

        public void AddBindingParameters(ServiceEndpoint endpoint, System.ServiceModel.Channels.BindingParameterCollection bindingParameters)
        {

        }

        public void ApplyClientBehavior(ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.ClientRuntime clientRuntime)
        {
            clientRuntime.MessageInspectors.Add(new MessageInspector());
        }

        public void ApplyDispatchBehavior(ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.EndpointDispatcher endpointDispatcher)
        {
            endpointDispatcher.DispatchRuntime.MessageInspectors.Add(new MessageInspector());
        }

        public void Validate(ServiceEndpoint endpoint)
        {

        }

        #endregion
    }
}

實現了上述兩個類，我們就基本搞定了第一個問題：如何自定義消息記錄，下面我們來探討如何實現自定義Formatter。WCF提供了IClientMessageFormatter和IDispatchMessageFormatter兩個接口類分別用于客戶端和服務端的編解碼。

public interface IClientMessageFormatter

{

// Methods

object DeserializeReply(Message message, object[] parameters);

Message SerializeRequest(MessageVersion messageVersion, object[] parameters);

}

public interface IDispatchMessageFormatter

{

// Methods

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

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

}

實現這兩個接口，就實現了自定義的編碼器，但說句實在的，要實現完整通用的編碼器并不是容易的事情。偷偷通過.Net Reflactor查看了下.Net Framework源碼，缺省的實現代碼量至少也有上千行了。我這次實現自定義的Formatter,其實是修改缺省Formatter編碼好的消息，將消息的正文<S:Body></S:Body>中的內容轉變成Base64字符串，然后在編碼到另外的消息中的形式來實現自定義消息編碼的。這個過程有三個主要的難點：

如何創建自定義的Message對象

如何將原始消息轉換為Base64正文的消息
如何從Base64正文消息轉換為原始消息。

我通過三個函數，分別實現了這三個難點：

1. 自定義的BodyWriter

代碼

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.ServiceModel.Channels;

using System.Xml;

namespace RobinLib

{

public class MyBodyWriter : BodyWriter

{

string body = "";

XmlDocument doc;

public MyBodyWriter(string body)

: base(true)

{

this.body = body;

}

public MyBodyWriter(XmlDocument doc)

: base(true)

{

this.doc = doc;

}

protected override void OnWriteBodyContents(XmlDictionaryWriter writer)

{

XmlWriterSettings setting = new XmlWriterSettings();

setting.NewLineHandling = NewLineHandling.Entitize;

setting.CheckCharacters = false;

if (!string.IsNullOrEmpty(body))

{

writer.WriteRaw(body);

}

if (doc != null)

{

doc.WriteContentTo(writer);

writer.Flush();

}

}

}

}

2. 轉換原始消息為Base64正文的消息

代碼

private Message Base64BodyMessage(Message ora_msg)

{

MemoryStream ms = new MemoryStream();

XmlDictionaryWriter writer = XmlDictionaryWriter.CreateTextWriter(ms, Encoding.UTF8);

ora_msg.WriteBodyContents(writer);

writer.Flush();

string body = System.Text.Encoding.UTF8.GetString(ms.GetBuffer());

byte[] buffer = System.Text.Encoding.UTF8.GetBytes(body);

body = Convert.ToBase64String(buffer);

Message msg = Message.CreateMessage(ora_msg.Version, ora_msg.Headers.Action, new MyBodyWriter(body));

ora_msg.Close();

return msg;

}

3. 轉換Base64消息為原始消息

代碼

private Message RestoreMessageFormBase64Message(Message message)

{

Message msg = null;

MemoryStream ms = new MemoryStream();

XmlDictionaryWriter writer = XmlDictionaryWriter.CreateTextWriter(ms, Encoding.UTF8);

message.WriteBody(writer);

writer.Flush();

string body = System.Text.Encoding.UTF8.GetString(ms.GetBuffer());

int index = body.IndexOf(">");

int index2 = body.IndexOf("</");

body = body.Substring(index + 1, index2 - index - 1);

byte[] buffer2 = Convert.FromBase64String(body);

body = System.Text.Encoding.UTF8.GetString(buffer2);

XmlDocument doc = new XmlDocument();

doc.LoadXml(body);

msg = Message.CreateMessage(message.Version, message.Headers.Action, new MyBodyWriter(doc));

msg.Headers.FaultTo = message.Headers.FaultTo;

msg.Headers.From = message.Headers.From;

msg.Headers.MessageId = message.Headers.MessageId;

msg.Headers.RelatesTo = message.Headers.RelatesTo;

msg.Headers.ReplyTo = message.Headers.ReplyTo;

msg.Headers.To = message.Headers.To;

foreach (var mh in message.Headers)

{

if (mh is MessageHeader)

{

if (mh.Name != "Action" && mh.Name != "FaultTo" && mh.Name != "From" && mh.Name != "MessageID" && mh.Name != "RelatesTo" && mh.Name != "ReplyTo" && mh.Name != "To")

{

msg.Headers.Add(mh as MessageHeader);

}

}

}

msg.Properties.Clear();

foreach (var p in message.Properties)

{

msg.Properties[p.Key] = p.Value;

}

return msg;

}

完整的代碼見附件。實現了自定義的Formatter，我們還需要通過擴展OperationBehavior，將應用Formatter，因此我們創建了Base64BodyBehavior，代碼為：

代碼

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.ServiceModel.Description;

namespace RobinLib

{

/// <summary>

/// 將消息主題序列為base64的OperationBehavior

/// </summary>

public class Base64BodyBehavior : IOperationBehavior

{

#region IOperationBehavior 成員

public void AddBindingParameters(OperationDescription operationDescription, System.ServiceModel.Channels.BindingParameterCollection bindingParameters)

{

}

public void ApplyClientBehavior(OperationDescription operationDescription, System.ServiceModel.Dispatcher.ClientOperation clientOperation)

{

clientOperation.SerializeRequest = true;

clientOperation.DeserializeReply = true;

clientOperation.Formatter = new Base64BodyFormatter(clientOperation.Formatter);

}

public void ApplyDispatchBehavior(OperationDescription operationDescription, System.ServiceModel.Dispatcher.DispatchOperation dispatchOperation)

{

dispatchOperation.DeserializeRequest = true;

dispatchOperation.SerializeReply = true;

dispatchOperation.Formatter = new Base64BodyFormatter(dispatchOperation.Formatter);

}

public void Validate(OperationDescription operationDescription)

{

}

#endregion

}

}

好了，目前我們已經將自定義消息記錄和自定義編碼器基本實現了，現在就涉及到如何在服務器代碼和客戶端代碼中添加EndpointBehavior和OperationBehavior，我們用純代碼的形式做了一下實現，

1. 在服務器托管代碼中：

代碼

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.ServiceModel;

namespace Robin_Wcf_Host_Console

{

class Program

{

static void Main(string[] args)

{

//服務地址

Uri baseAddress = new Uri("net.tcp://127.0.0.1:8081/Robin_Wcf_Formatter");

ServiceHost host = new ServiceHost(typeof(Robin_Wcf_SvcLib.Service1), new Uri[] { baseAddress });

//服務綁定

NetTcpBinding bind = new NetTcpBinding();

host.AddServiceEndpoint(typeof(Robin_Wcf_SvcLib.IService1), bind, "");

if (host.Description.Behaviors.Find<System.ServiceModel.Description.ServiceMetadataBehavior>() == null)

{

System.ServiceModel.Description.ServiceMetadataBehavior svcMetaBehavior = new System.ServiceModel.Description.ServiceMetadataBehavior();

svcMetaBehavior.HttpGetEnabled = true;

svcMetaBehavior.HttpGetUrl = new Uri("http://127.0.0.1:8001/Mex");

host.Description.Behaviors.Add(svcMetaBehavior);

}

host.Opened+=new EventHandler(delegate(object obj,EventArgs e){

Console.WriteLine("服務已經啟動！");

});

foreach (var sep in host.Description.Endpoints)

{

sep.Behaviors.Add(new RobinLib.OutputMessageBehavior());

foreach (var op in sep.Contract.Operations)

{

op.Behaviors.Add(new RobinLib.Base64BodyBehavior());

}

}

host.Open();

Console.Read();

}

}

}

2. 在客戶端代理代碼中：

代碼

[System.Diagnostics.DebuggerStepThroughAttribute()]

[System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "3.0.0.0")]

public partial class Service1Client : System.ServiceModel.ClientBase<Robin_Wcf_ClientApp.Robin_Wcf_Formatter_Svc.IService1>, Robin_Wcf_ClientApp.Robin_Wcf_Formatter_Svc.IService1

{

public Service1Client()

{

base.Endpoint.Behaviors.Add(new RobinLib.OutputMessageBehavior());

foreach (var op in base.Endpoint.Contract.Operations)

{

op.Behaviors.Add(new RobinLib.Base64BodyBehavior());

}

}

public Service1Client(string endpointConfigurationName) :

base(endpointConfigurationName)

{

base.Endpoint.Behaviors.Add(new RobinLib.OutputMessageBehavior());

foreach (var op in base.Endpoint.Contract.Operations)

{

op.Behaviors.Add(new RobinLib.Base64BodyBehavior());

}

}

public Service1Client(string endpointConfigurationName, string remoteAddress) :

base(endpointConfigurationName, remoteAddress)

{

base.Endpoint.Behaviors.Add(new RobinLib.OutputMessageBehavior());

foreach (var op in base.Endpoint.Contract.Operations)

{

op.Behaviors.Add(new RobinLib.Base64BodyBehavior());

}

}

public Service1Client(string endpointConfigurationName, System.ServiceModel.EndpointAddress remoteAddress) :

base(endpointConfigurationName, remoteAddress)

{

base.Endpoint.Behaviors.Add(new RobinLib.OutputMessageBehavior());

foreach (var op in base.Endpoint.Contract.Operations)

{

op.Behaviors.Add(new RobinLib.Base64BodyBehavior());

}

}

public Service1Client(System.ServiceModel.Channels.Binding binding, System.ServiceModel.EndpointAddress remoteAddress) :

base(binding, remoteAddress)

{

base.Endpoint.Behaviors.Add(new RobinLib.OutputMessageBehavior());

foreach (var op in base.Endpoint.Contract.Operations)

{

op.Behaviors.Add(new RobinLib.Base64BodyBehavior());

}

}

public string GetData(int value)

{

return base.Channel.GetData(value);

}

public Robin_Wcf_ClientApp.Robin_Wcf_Formatter_Svc.CompositeType GetDataUsingDataContract(Robin_Wcf_ClientApp.Robin_Wcf_Formatter_Svc.CompositeType composite)

{

return base.Channel.GetDataUsingDataContract(composite);

}

}

最后，我們比較一下記錄到的原始消息和經過Base64 正文消息的對比

客戶端請求原始消息

客戶端Base64正文后消息：

服務器端原始消息：

服務端Base64正文后消息：

想要學習WCF的一些基礎知識可以訪問如下鏈接：

	WCF從理論到實踐一：揭開神秘面紗

	WCF從理論到實踐二：決戰紫禁之巔

	WCF從理論到實踐三：八號當鋪之黑色契約

	WCF從理論到實踐四：路在何方

	WCF從理論到實踐：Binding細解

	WCF從理論到實踐：WCF架構

	WCF從理論到實踐：消息交換模式

	WCF從理論到實踐：事件廣播

	WCF從理論到實踐:實例模式和對象生命周期

	WCF從理論到實踐：異常處理

	WCF從理論到實踐-異步

	WCF從理論到實踐:事務

	WCF從理論到實踐:事務投票

	WCF從理論到實踐(14):WCF解決方案模板

	WCF從理論到實踐(15):響應變化

	WCF從理論到實踐(16):操作重載（帶視頻+ppt+源碼）

	WCF從理論到實踐(17):OO大背離（帶視頻+ppt+源碼）

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	Ajax與WCF交互-WCF之美

	Ajax與Wcf交互-JSON

	ExtJs與WCF交互:生成樹

	用ExtJs+Linq+Wcf打造簡單grid

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	ExtJs與WCF之間的跨域訪問

	異步調用Restful的WCF服務

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