WCF之消息

在WCF中客户端与服务端都是靠消息进行传输的，消息格式和SOAP一样，具有消息标头和正文。客户端和服务端之间的所有通讯最终都会产生System.ServiceModel.Channels. Message

实例。在平时操作中，很少直接操作Message类型，而是通过WCF服务模型构造（如数据契约、消息契约和操作契约）来描述传入消息和传出消息。所以，要想透彻的理解WCF有必要对Message多些了解。下面看一个简单的类，来了解一下Message用到的类。

using System;
using System.ServiceModel;
using System.Runtime.Serialization;
using System.IO;
using System.Xml;
using System.Text;
using System.ServiceModel.Channels;

namespace WcfMessage
{
    [DataContract(Namespace="http://www.cnblogs.com/qiuwuyu")]
public class Fruit
    {
private string m_Name = string.Empty;
private string m_Price = string.Empty;
public Fruit(string name, string price)
        {
            m_Name = name;
            m_Price = price;
        }
        [DataMember]
public string Name
        {
get{ return m_Name; }
set{ m_Name = value; }
        }
        [DataMember]
public string Price
        {
get { return m_Price; }
set { m_Price = value; }
        }
    }
    [DataContract(Namespace = "http://www.cnblogs.com/qiuwuyu")]
public class FruitHeader
    {
private string m_HeaderKey = string.Empty;
        [DataMember]
public string HeaderKey
        {
get { return m_HeaderKey; }
set { m_HeaderKey = value; }
        }
public FruitHeader(string key)
        {
            m_HeaderKey=key;
        }
    }
class Program
    {
static void Main(string[] args)
        {
            Fruit fruit = new Fruit("banana", "6.00");
//把Fruit类型序列化为xml文件
            using (FileStream fs = new FileStream("Fruit.xml", FileMode.Create))
            {
                DataContractSerializer dataSer = new DataContractSerializer(typeof(Fruit));
                dataSer.WriteObject(fs, fruit);
            }

            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load("Fruit.xml");
//用二进制编码的xml文档
           using (FileStream binStream = new FileStream("Fruit.bin", FileMode.Create))
            {
using (XmlWriter xw = XmlDictionaryWriter.CreateBinaryWriter(binStream))
                {
                    xmlDoc.WriteContentTo(xw);
                }
            }
//用mtom编码的xml文档
            using (FileStream mtomStream = new FileStream("Fruit.mtom", FileMode.Create))
            {
using (XmlWriter xw = XmlDictionaryWriter.CreateMtomWriter(mtomStream, Encoding.UTF8, 1024, "text/xml"))
                {
                    xmlDoc.WriteTo(xw);
                }
            }

//创建一消息，并用文本编码的消息
            Message message1 = Message.CreateMessage(MessageVersion.Soap11WSAddressingAugust2004, "*", fruit);
            MessageHeader mHeader = MessageHeader.CreateHeader("FruitHeader", "http://www.cnblogs.com/qiuwuyu",
                                                                  new FruitHeader("password"));
            message1.Headers.Add(mHeader);
using (FileStream stream = new FileStream("FruitMessageHeader.xml", FileMode.Create))
            {
using (XmlWriter xw = XmlDictionaryWriter.CreateTextWriter(stream))
                {
                    message1.WriteMessage(xw);
                }
            }
//创建一个没有消息版本，并用文本编码的消息
            Message message = Message.CreateMessage(MessageVersion.None, "*", new XmlNodeReader(xmlDoc));
using (FileStream stream = new FileStream("FruitMessageNone.xml", FileMode.Create))
            {
using (XmlWriter xw = XmlDictionaryWriter.CreateTextWriter(stream))
                {
                    message.WriteMessage(xw);
                }
            }
        }
    }
}

XmlDictionary是定义了一个私有的可以表示SOAP消息中元素名字、属性和XML namespace声明的key-value列表的字典结构。字典在常见文本字符串和整数之间建立映射，并为压缩和解压缩XML提供一种有效机制。XmlDictionaryWriter是WCF中一个优化的读取XML编写器。

执行上述代码后，查看生成文件。

Fruit.xml文件：

二进制编码的Fruit.xml文件：

MTOM编码的Fruit.xml文件：

文本编码的消息：

无消息版本信息本文本编码的消息：

下面看一个直接用Message写的小实例，从整体上感觉下。

服务契约：

using System;
using System.ServiceModel;
using System.ServiceModel.Channels;
using FruitModel;

namespace IFruitService
{
    [ServiceContract(Namespace = "http://www.cnblogs.com/qiuwuyu")]
public interface IFruitPriceService
    {
        [OperationContract(Action="*",ReplyAction="*")]
        Message GetFruit(Message m);
    }
}

Action指定为“*”表示可以处理服务端接收到的任何消息。如果没有指定Action值，则默认为服务约定命名空间/约定名称（默认为接口名称）/操作名称（默认为方法名称）。


using System;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Channels;
using IFruitService;
using FruitModel;

namespace FruitPriceService
{
public class FruitPriceService : IFruitPriceService
    {
public Message GetFruit(Message m)
        {
if ( OperationContext.Current.IncomingMessageHeaders.GetHeader<FruitHeader>(0).HeaderKey!="password" )
            {
                FaultCode faultCode = new FaultCode("Invalid Key");
return Message.CreateMessage(m.Version, faultCode, "Invalid Key", "*");
            }
return Message.CreateMessage(m.Version, "*", new Fruit("banana", "6.00"));
        }
    }
}