[WCF 学习笔记] 4. 消息操作

WCF 的一切都是围绕着 Message 进行，那么 Message 究竟是什么样子？

[ServiceContract]
public interface ICalculate
{
[OperationContract]
double Add(double a, double b);
}

public class CalculateService : ICalculate
{
public double Add(double a, double b)
{
Message msg = OperationContext.Current.RequestContext.RequestMessage;
Console.WriteLine(msg);

return a + b;
}
}

public class WcfTest
{
public static void Test()
{
AppDomain.CreateDomain("Server").DoCallBack(delegate
{
ServiceHost host = new ServiceHost(typeof(CalculateService));
host.AddServiceEndpoint(typeof(ICalculate), new BasicHttpBinding(),
"http://localhost:8080/calc");

host.Open();
});

ChannelFactory<ICalculate> factory = new ChannelFactory<ICalculate>(new BasicHttpBinding(),
"http://localhost:8080/calc");
ICalculate o = factory.CreateChannel();
Console.WriteLine(o.Add(1, 2));
}
}

输出

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
<s:Header>
<To s:mustUnderstand="1" xmlns="http://...">http://localhost:8080/calc</To>
<Action s:mustUnderstand="1" xmlns="http://...">http://tempuri.org/ICalculate/Add</Action>
</s:Header>
<s:Body>
<Add xmlns="http://tempuri.org/">
<a>1</a>
<b>2</b>
</Add>
</s:Body>
</s:Envelope>

事实上我们可以直接基于 Message Layer 进行编程，利用 OperationContract.Action 捕获特定 Action 的消息。

[ServiceContract]
public interface ICalculate
{
[OperationContract(Action = "Add", ReplyAction="Add")]
Message ProcessMessage(Message m);
}

public class CalculateService : ICalculate
{
public Message ProcessMessage(Message m)
{
Data d = m.GetBody<Data>();
Console.WriteLine(d.I);

return Message.CreateMessage(MessageVersion.Soap11, "Add", new Data(9999));
}
}

[DataContract]
public class Data
{
[DataMember]
public int I;

public Data(int i)
{
this.I = i;
}
}

public class WcfTest
{
public static void Test()
{
AppDomain.CreateDomain("Server").DoCallBack(delegate
{
ServiceHost host = new ServiceHost(typeof(CalculateService));
host.AddServiceEndpoint(typeof(ICalculate), new BasicHttpBinding(),
"http://localhost:8080/calc");

host.Open();
});

ChannelFactory<IRequestChannel> factory = new ChannelFactory<IRequestChannel>(
new BasicHttpBinding(), "http://localhost:8080/calc");
IRequestChannel channel = factory.CreateChannel();
channel.Open();

Message request = Message.CreateMessage(MessageVersion.Soap11, "Add", new Data(1234));
Message reply = channel.Request(request);
Console.WriteLine("-------------------");
Console.WriteLine(reply);

channel.Close();
factory.Close();
}
}

输出：

1234
-------------------
<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
<s:Header />
<s:Body>
<Data xmlns="http://..." xmlns:i="http://...">
<I>9999</I>
</Data>
</s:Body>
</s:Envelope>

正
如上面所看到的，所有的调用都被转换成消息后发送。这也符合 SOA 的规范，完全隔离，清晰的边界。(调用
"m.GetBody<Data>()" 后，会导致 Message.State 变更，再次访问会出错，有关详细信息请参考 MSDN
文档。)

我们还可以使用 MessageContractAttribute / MessageHeaderAttribute
来控制消息格式，这比 DataContractAttribute
要更加灵活。我们可以设置消息标头、消息体，包括是否对其中某些进行签名和加密处理。

[ServiceContract]
public interface ICalculate
{
[OperationContract]
void Add(Data d);
}

public class CalculateService : ICalculate
{
public void Add(Data d)
{
Console.WriteLine(OperationContext.Current.RequestContext.RequestMessage);
Console.WriteLine("----------------");
Console.WriteLine("{0}/{1}", d.a, d.b);
}
}

[MessageContract]
public class Data
{
[MessageHeader]
public double a = 1;

[MessageBodyMember]
public double b = 2;
}

public class WcfTest
{
public static void Test()
{
AppDomain.CreateDomain("Server").DoCallBack(delegate
{
ServiceHost host = new ServiceHost(typeof(CalculateService));
host.AddServiceEndpoint(typeof(ICalculate), new BasicHttpBinding(),
"http://localhost:8080/calc");

host.Open();
});

ChannelFactory<ICalculate> factory = new ChannelFactory<ICalculate>(new BasicHttpBinding(),
"http://localhost:8080/calc");
ICalculate o = factory.CreateChannel();

Data d = new Data();
d.a = 1234;
d.b = 5678;
o.Add(d);
}
}

输出：

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
<s:Header>
<h:a xmlns:h="http://tempuri.org/">1</h:a>
<To s:mustUnderstand="1" xmlns="http://s...">http://localhost:8080/calc</To>
<Action s:mustUnderstand="1" xmlns="http://...">http://tempuri.org/ICalculate/Add</Action>
</s:Header>
<s:Body>
<Data xmlns="http://tempuri.org/">
<b>2</b>
</Data>
</s:Body>
</s:Envelope>
----------------
1234/5678

有关 Message 更详细的信息，可以参考 MSDN (Microsoft Windows SDK) 文档。