WCF开发框架之ICommunicationObject 对象详解
WCF开发框架之ICommunicationObject 对象详解
ICommunicationObject 接口
C# Code:
public interface ICommunicationObject
{
CommunicationState State { get; }
event EventHandler Opening;
event EventHandler Faulted;
event EventHandler Closing;
event EventHandler Closed;
event EventHandler Opened;
void Abort();
IAsyncResult BeginClose(TimeSpan timeout, AsyncCallback callback, object state);
IAsyncResult BeginClose(AsyncCallback callback, object state);
IAsyncResult BeginOpen(TimeSpan timeout, AsyncCallback callback, object state);
IAsyncResult BeginOpen(AsyncCallback callback, object state);
void Close(TimeSpan timeout);
void Close();
void EndClose(IAsyncResult result);
void EndOpen(IAsyncResult result);
void Open(TimeSpan timeout);
void Open();
}
//来源:C/S框架网 | www.csframework.com | QQ:23404761
{
CommunicationState State { get; }
event EventHandler Opening;
event EventHandler Faulted;
event EventHandler Closing;
event EventHandler Closed;
event EventHandler Opened;
void Abort();
IAsyncResult BeginClose(TimeSpan timeout, AsyncCallback callback, object state);
IAsyncResult BeginClose(AsyncCallback callback, object state);
IAsyncResult BeginOpen(TimeSpan timeout, AsyncCallback callback, object state);
IAsyncResult BeginOpen(AsyncCallback callback, object state);
void Close(TimeSpan timeout);
void Close();
void EndClose(IAsyncResult result);
void EndOpen(IAsyncResult result);
void Open(TimeSpan timeout);
void Open();
}
//来源:C/S框架网 | www.csframework.com | QQ:23404761
ICommunicationState状态
C# Code:
public enum CommunicationState
{
Created = 0,
Opening = 1,
Opened = 2,
Closing = 3,
Closed = 4,
Faulted = 5
}
//来源:C/S框架网 | www.csframework.com | QQ:23404761
{
Created = 0,
Opening = 1,
Opened = 2,
Closing = 3,
Closed = 4,
Faulted = 5
}
//来源:C/S框架网 | www.csframework.com | QQ:23404761
CommunicationState枚举列举了通信对象改变的6个状态。所有通信对象的初始状态是Created.这是通信对象被初始化时的状 态。所有通信对象的最后状态时Closed.在这个方式中，在ICommunicationObject接口上调用的方法将通信对象从一个状态转移到另一 个状态。比如，Open() 方法被调用来传输一个通信对象并使其的状态从Created变成Opened。图3.5显示了一个显示了通信对象的状态和通信对象状态切换的示意图。
通信对象的一个例子是ClientBase<>类，是通过Visual Studio 的添加服务引用或者svcutil.exe生成的客户端的基础实现。
注意: 不能重用客户端
当一个通信对象已经由Opened状态变成Closing或者Faulted状态后就无法再变回去。这意味着通信状态不能回到Opened状态除非首先重建通信对象。因此，当客户端被关闭(当他们的状态时Closed时)以后它们需要被重新创建。
ICommunicationObject接口支持五个事件(Opening, Opened, Closing, Closed和Faulted).这些事件用来通知代码状态改变。
提示：客户端通知
应用程序维护一个到客户端代理的引用是很平常的。当客户端代理进入Faulted 状态(最后是Closed状态)时，使用状态转换事件来提醒是很重要的，因为这样客户端和服务端的通信才能保持。
使用ICommunicationObject接口时，通常通过把一个已有的通信对象强制转换成接口来获取对 ICommunicationObject暴露的事件和方法的访问能力。然后，还有些情况你需要创建一个新的通信对象来扩展WCF的能力。这种情况 下，WCF提供了一个称为CommunicationObject的抽象的基类，它提供了ICommunicationObject接口和相关状态机的实 现。列表3.10显示了一个由svcutil.exe生成的StockQuoteServiceClient类。这个客户的继承自 ClientBase<>类。代码显示了客户端被强转成一个ICommunicationObject接口以便于我们可以接受通信对象。
C# Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;
using System.ServiceModel.Channels;
namespace EssentialWCF
{
class Program
{
static void Main( string [] args)
{
string symbol = " MSFT " ;
double value;
StockQuoteServiceClient client = new StockQuoteServiceClient();
ICommunicationObject commObj = (ICommunicationObject)client;
commObj.Closed += new EventHandler(Closed);
commObj.Faulted += new EventHandler(Faulted);
value = client.GetQuote(symbol);
Console.WriteLine( " {0}@{1} " , symbol, value);
Console.ReadLine();
}
static void Closed( object sender, EventArgs e)
{
// Handle Closed Event
}
static void Faulted( object sender, EventArgs e)
{
// Handle Faulted Event
}
}
}
//来源:C/S框架网 | www.csframework.com | QQ:23404761
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;
using System.ServiceModel.Channels;
namespace EssentialWCF
{
class Program
{
static void Main( string [] args)
{
string symbol = " MSFT " ;
double value;
StockQuoteServiceClient client = new StockQuoteServiceClient();
ICommunicationObject commObj = (ICommunicationObject)client;
commObj.Closed += new EventHandler(Closed);
commObj.Faulted += new EventHandler(Faulted);
value = client.GetQuote(symbol);
Console.WriteLine( " {0}@{1} " , symbol, value);
Console.ReadLine();
}
static void Closed( object sender, EventArgs e)
{
// Handle Closed Event
}
static void Faulted( object sender, EventArgs e)
{
// Handle Faulted Event
}
}
}
//来源:C/S框架网 | www.csframework.com | QQ:23404761
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