WCF之契约
以下是WCF常用的三种契约，
服务契约：服务契约描述服务所实现的功能操作。服务契约将.NET类型中的元素映射到WSDL元素。服务契约中的操作契约描述了实现服务功能的方法。
数据契约：数据契约描述了服务端与客户端通讯时使用的数据结构。数据契约将CLR数据类型映射到XML模式定义（XML Schema Definition,XSD），并定义如何对其进行序列化和反序列化。
消息契约：消息契约将CLR类型映射成SOAP消息，描述SOAP消息的格式，并影响这些消息的WSDL和XSD定义。消息契约可以精确地控制SOAP信头和信体。
下面以水果类为例，写一些简单的代码，来演示下契约
服务契约：
using System.ServiceModel;
using FruitModel;
namespace IFruitPrice
{
[ServiceContract(Namespace = "http://www.cnblogs.com/qiuwuyu")]
public interface IFruitPriceService
{
[OperationContract]
Fruit GetFruit();
}
}
服务端实现：
using FruitModel;
using IFruitPrice;
namespace FruitPrice
{
public class FruitPriceService : IFruitPriceService
{
public Fruit GetFruit()
{
Fruit f = new Fruit();
f.Name = "banana";
f.Price = "6.00";
return f;
}
}
}
数据契约：
using System.ServiceModel;
using System.Runtime.Serialization;
namespace FruitModel
{
[DataContract]
public class Fruit
{
[DataMember]
private string m_Name;
[DataMember]
private string m_Price;
public string Name
{
get
{
return m_Name;
}
set
{
m_Name = value;
}
}
public string Price
{
get
{
return m_Price;
}
set
{
m_Price = value;
}
}
}
}
寄存服务：
using System;
using System.ServiceModel;
using System.ServiceModel.Description;
using FruitPrice;
using IFruitPrice;
namespace WcfFruitHost
{
class Program
{
static void Main(string[] args)
{
using (ServiceHost host = new ServiceHost(typeof(FruitPriceService),
new Uri("http://localhost:8000/Fruit")))
{
host.AddServiceEndpoint(typeof(IFruitPriceService), new BasicHttpBinding(), "FruitService");
ServiceMetadataBehavior behavior = new ServiceMetadataBehavior();
behavior.HttpGetEnabled = true;
host.Description.Behaviors.Add(behavior);
host.AddServiceEndpoint(typeof(IMetadataExchange),
MetadataExchangeBindings.CreateMexHttpBinding(), "mex");
host.Open();
Console.WriteLine("Fruit Service Is Running...");
Console.ReadLine();
}
}
}
}
客户端调用：
using System;
using System.ServiceModel;
using IFruitPrice;
using FruitModel;
namespace WcfFruitClient
{
class Program
{
static void Main(string[] args)
{
EndpointAddress epAddr = new EndpointAddress("http://localhost:8000/Fruit/FruitService");
IFruitPriceService proxy = ChannelFactory<IFruitPriceService>.CreateChannel(new BasicHttpBinding(), epAddr);
Console.WriteLine("Name:" + proxy.GetFruit().Name + " Price:" + proxy.GetFruit().Price);
Console.WriteLine("Fruit Client Is Running...");
Console.ReadLine();
}
}
}
程序执行结果如下：
生成的WSDL如下：
下面是为数据契约生成的XSD：
修改一下代码，演示消息契约
数据契约通过XSD标准来达成互通性，消息契约则可以与任何通过SOAP通信的系统互通。消息契约可以直接访问SOAP的消息头和消息体，从而可以完全掌控服务所收发的SOAP消息。所以需要精确定义SOAP各部分内容时可以从DataContract 转用MessageContract。
修改数据契约为消息契约
using System.ServiceModel;
using System.Runtime.Serialization;
namespace FruitModel
{
[MessageContract(WrapperNamespace = "http://www.cnblogs.com/qiuwuyu")]
public class FruitKey
{
[MessageHeader]
private string m_Key;
public string Key
{
get
{
return m_Key;
}
set
{
m_Key = value;
}
}
}
[MessageContract(WrapperNamespace = "http://www.cnblogs.com/qiuwuyu")]
public class Fruit
{
[MessageBodyMember]
private string m_Name;
[MessageBodyMember]
private string m_Price;
public string Name
{
get
{
return m_Name;
}
set
{
m_Name = value;
}
}
public string Price
{
get
{
return m_Price;
}
set
{
m_Price = value;
}
}
}
}
增加一个类做为消息头，可以添加一些安全验证信息。
修改服务契约传递参数
using System.ServiceModel;
using FruitModel;
namespace IFruitPrice
{
[ServiceContract(Namespace = "http://www.cnblogs.com/qiuwuyu")]
public interface IFruitPriceService
{
[OperationContract]
Fruit GetFruit(FruitKey key);
}
}
修改服务实现
using FruitModel;
using IFruitPrice;
using System.ServiceModel;
namespace FruitPrice
{
public class FruitPriceService : IFruitPriceService
{
public Fruit GetFruit(FruitKey key)
{
if (!key.Key.Equals( "wcf"))
{
throw new FaultException("Invalid Key");
}
Fruit f = new Fruit();
f.Name = "banana";
f.Price = "6.00";
return f;
}
}
}
修改客户端调用
using System;
using System.ServiceModel;
using IFruitPrice;
using FruitModel;
namespace WcfFruitClient
{
class Program
{
static void Main(string[] args)
{
EndpointAddress epAddr = new EndpointAddress("http://localhost:8000/Fruit/FruitService");
IFruitPriceService proxy = ChannelFactory<IFruitPriceService>.CreateChannel(new BasicHttpBinding(), epAddr);
FruitKey key = new FruitKey();
key.Key = "w";
Fruit f=null;
try
{
f = proxy.GetFruit(key);
}
catch (Exception ex)
{
f=null;
Console.WriteLine(ex.Message);
}
if (f != null)
{
Console.WriteLine("Name:" + f.Name + " Price:" + f.Price);
}
Console.WriteLine("Fruit Client Is Running...");
Console.ReadLine();
}
}
}
传入一个错误的key ,运行结果
把key改为wcf后，运行结果
如果想看数据契约和消息契约生成的元数据有何不同，可以用SvcUtil.exe工具查看，用如下命令
