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）。
ReplyAction为“*”表示不向消息中添加答复操作。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）Response。
在客户端应用程序中指定星号可指示 不验证答复操作。服务实现：
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 " ));
}
}
}寄存服务：
客户端调用：
using System.ServiceModel;
using IFruitService;
namespace WcfMessageHost
{
class Program
{
static void Main( string [] args)
{
using (ServiceHost host = new ServiceHost( typeof (FruitPriceService.FruitPriceService),
new Uri( " http://localhost:8000/Fruit " )))
{
host.AddServiceEndpoint( typeof (IFruitPriceService), new BasicHttpBinding(), " FruitService " );
host.Open();
Console.WriteLine( " Fruit Service Is Running... " );
Console.ReadLine();
}
}
}
}传入正确的HeaderKey的执行结果：
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.Runtime.Serialization;
using IFruitService;
using FruitModel;
namespace WcfMessageClient
{
class Program
{
static void Main( string [] args)
{
EndpointAddress epAddr = new EndpointAddress( " http://localhost:8000/Fruit/FruitService " );
IFruitPriceService proxy = ChannelFactory < IFruitPriceService > .CreateChannel( new BasicHttpBinding(), epAddr);
MessageHeader mHeader = MessageHeader.CreateHeader( " FruitHeader " , " http://www.cnblogs.com/qiuwuyu " ,
new FruitHeader( " password " ));
Message message = Message.CreateMessage(MessageVersion.Soap11, " * " , string .Empty);
message.Headers.Add(mHeader);
Message m = proxy.GetFruit(message);
if (m.IsFault)
{
Console.WriteLine(m.ToString());
}
else
{
Fruit fruit = m.GetBody < Fruit > ();
Console.WriteLine( " Name: " + fruit.Name + " Price: " + fruit.Price);
}
Console.WriteLine( " Fruit Client Is Running... " );
Console.ReadLine();
}
}
}
传入错误的HeaderKey的执行结果：
如果HeaderKey不正确可以返回一个FaultMessage，如下 FaultCode faultCode = new FaultCode("InvalidKey"); return Message.CreateMessage(m.Version,faultCode, "Invalid Key", "*"); 在客户端可以用IsFault判断是否是FaultMessage并进行一些相应的逻辑处理。