Silverlight与WCF之间的通信(2)利用WCF的双工通信“推送”给SL数据

转载

flydragon0815 2011-12-05 00:19:05 博主文章分类：C#

文章标签 职场休闲 Silverlight WCF 双工通信“推送”给SL数据 文章分类 服务器

一，Duplex简介

上一个随笔记录了SL利用Timer定时去WCF上取数据再绑定到界面上的问题，今天尝试用了WCF的Duplex双工通信来做这个事情，也以这个例子来说明WCF中Duplex的使用。

双工通信的原理很简单，我们平时用的是客户端调用服务端的方法来获取数据，而Duplex是将客户端也当作了服务器，客户端上的方法也可以被调用，以聊天功能为例子，用户A连接到服务器后，之前的做法是客户端定时取数据，而Duplex是在服务端定时检测数据变化，如果发现了发送给A的信息，那么立即会调用客户端的方法来推送信息到A。

二，建立Duplex模式的WCF服务

这里以一个简单的聊天功能来说明，WCF提供了三个方法，连接到服务器方法，发送信息方法和接收信息方法。从服务契约上来说分为两个接口，分别是为客户端提供发送信息和开始聊天方法的IChatService接口和服务器调用客户端方法的IChatServiceCallBack接口

IChatService.cs文件

Silverlight与WCF之间的通信(2)利用WCF的双工通信“推送”给SL数据 _Silverlight_02

代码

namespace ChatWCF
{
[ServiceContract(CallbackContract=typeof(IChatServiceCallBack))]//这里需要定义IChatService接口的回调接口IChatServiceCallBack
public interface IChatService
{
[OperationContract]
bool SendMessage(MessageInfo msg); //发送信息

[OperationContract]
bool LoginChat(string User,string Partner);//开始聊天模式
}

[ServiceContract]
public interface IChatServiceCallBack //供服务端回调的接口
{
[OperationContract(IsOneWay=true)]
void ReceiveMessages(List<MessageInfo> listMessages);//客户端被服务端回调后接收信息
}
}

接下来需要实现这接口，IChatService.svc.cs

Silverlight与WCF之间的通信(2)利用WCF的双工通信“推送”给SL数据 _双工通信“推送”给SL数据 _04

代码

namespace ChatWCF
{
public class ChatService : IChatService
{
IChatServiceCallBack chatserviceCallBack;
string _user;
string _partner;
　　　　 Timer timer;
//开始聊天
public bool LoginChat(string User, string Partner)

{
try
{
chatserviceCallBack = OperationContext.Current.GetCallbackChannel<IChatServiceCallBack>();
_user = User;
_partner = Partner;

timer = new Timer(new TimerCallback(CheckMessages), this, 100, 100);

return true;
}
catch(Exception ex)
{
return false;
}
}
//检查消息并回调客户端接收此消息，此处是回调的重点
private void CheckMessages(object o)

{
chatserviceCallBack.ReceiveMessages(GetMessages(_user,_partner));
}

//发送信息
public bool SendMessage(MessageInfo msg)
{
[将MessageInfo写入数据库...]
}

//检测数据库
private List<MessageInfo> GetMessages(string User, string Partner)
{
List<MessageInfo> listMsg = new List<MessageInfo>();

[检测数据库并返回检测到的MessageInfo...]

return listMsg;
}

//执行简单的SQL语句
private DataSet ExcuteSQL(string strSql)
{
string strServer = "server=LEON-PC\\sql2005;database=jplan;uid=sa;pwd=sa;";
SqlConnection con = new SqlConnection(strServer);
con.Open();
SqlDataAdapter dataAdapter = new SqlDataAdapter(strSql, con);
DataSet ds = new DataSet();
dataAdapter.Fill(ds);
con.Close();

return ds;
}
}
}

这里需要注意一点的是这个WCF是建立在Duplex基础上的，所以在wcf的项目中需要添加一个程序集：

Assembly System.ServiceModel.PollingDuplex
C:\Program Files\Microsoft SDKs\Silverlight\v4.0\Libraries\Server\System.ServiceModel.PollingDuplex.dll

接下来需要对Web.config进行配置，主要是ServiceModel节点：

Silverlight与WCF之间的通信(2)利用WCF的双工通信“推送”给SL数据 _职场_06

代码

<system.serviceModel>
<behaviors>
<serviceBehaviors>
<behavior name="ChatWCF.ChatBehavior">
<serviceMetadata httpGetEnabled="true" />
<serviceDebug includeExceptionDetailInFaults="false" />
</behavior>
</serviceBehaviors>
</behaviors>
<services>
<service behaviorConfiguration="ChatWCF.ChatBehavior" name="ChatWCF.ChatService">
<endpoint
address=""
binding="pollingDuplexHttpBinding"
bindingConfiguration="multipleMessagesPerPollPollingDuplexHttpBinding"
contract="ChatWCF.IChatService">
</endpoint>
<endpoint
address="mex"
binding="mexHttpBinding"
contract="IMetadataExchange"/>
</service>
</services>
<extensions>
<bindingExtensions>
<add name=
"pollingDuplexHttpBinding"
type="System.ServiceModel.Configuration.PollingDuplexHttpBindingCollectionElement,System.ServiceModel.PollingDuplex, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
</bindingExtensions>
</extensions>

<bindings>
<pollingDuplexHttpBinding>
<binding name="multipleMessagesPerPollPollingDuplexHttpBinding"
duplexMode="MultipleMessagesPerPoll"
maxOutputDelay="00:00:07"/>
</pollingDuplexHttpBinding>
</bindings>
<serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
</system.serviceModel>

如果您的WCF服务是一个单独的站点，而客户端是SL的话，鉴于SL的安全性考虑不支持跨域访问，那么就需要在WCF的根目录下放置一个XML策略文件，文件名为

clientaccesspolicy.xml：

Silverlight与WCF之间的通信(2)利用WCF的双工通信“推送”给SL数据 _WCF_08

代码

<?xml version="1.0" encoding="utf-8"?>
<access-policy>
<cross-domain-access>
<policy>
<allow-from http-request-headers="SOAPAction">
<domain uri="*"/>
</allow-from>
<grant-to>
<resource path="/" include-subpaths="true"/>
</grant-to>
</policy>
</cross-domain-access>
</access-policy>

如果您的配置和代码书写正确，浏览一下WCF服务会发现下图，说明服务已经正确host到VS的轻量级IIS上了

三，Silverlight跨域访问WCF的Duplex服务

先建立一个单独的project，silverlight app，当然还是需要先引用WCF服务的：

新建一个SL文件，Chat.xaml代码，包括了一个发送消息窗口和一个显示聊天信息的窗口，这个聊天的窗口从普通HTML街面上接收两个参数，即user和partner互为聊天对象。

Silverlight与WCF之间的通信(2)利用WCF的双工通信“推送”给SL数据 _职场_12

代码

后台代码中需要从HTML中接收聊天对象:

Silverlight与WCF之间的通信(2)利用WCF的双工通信“推送”给SL数据 _休闲_14

代码

namespace ChatSL
{
public partial class Chat : UserControl
{
string user;
string partner;

EndpointAddress address ;
PollingDuplexHttpBinding binding;
ChatService.ChatServiceClient proxy;

public Chat()
{
InitializeComponent();

this.Loaded+=new RoutedEventHandler(Chat_Loaded);
this.txtMessage.KeyDown += new KeyEventHandler(KeyDownProcess);
this.btnSend.Click += new RoutedEventHandler(btnSend_Click);
this.btnClose.Click += new RoutedEventHandler(btnClose_Click);
}

void Chat_Loaded(object sender,RoutedEventArgs e)
{
HtmlElement element;
element = HtmlPage.Document.GetElementById("lbluser");
this.txtMe.Text = element.GetAttribute("innerText");
element = HtmlPage.Document.GetElementById("lblpartner");
this.txtPartner.Text = element.GetAttribute("innerText");

user = this.txtMe.Text;
partner = this.txtPartner.Text;

LogIn();
}
//向服务器示意上线
private void LogIn()
{
address = new EndpointAddress("http://localhost:32662/ChatService.svc%22);
binding = new PollingDuplexHttpBinding(PollingDuplexMode.MultipleMessagesPerPoll);
proxy = new ChatService.ChatServiceClient(binding,address);
proxy.ReceiveMessagesReceived+=new EventHandler<ChatService.ReceiveMessagesReceivedEventArgs>(proxy_ReceiveMessagesReceived);
proxy.LoginChatAsync(user, partner);
}

#region 绑定数据
void proxy_ReceiveMessagesReceived(object sender,ChatService.ReceiveMessagesReceivedEventArgs e)
{
this.listMsgs.ItemsSource = e.listMessages;
}

private void SetDataSource()
{

}
#endregion

#region 键盘事件
protected void KeyDownProcess(object sender, KeyEventArgs e)
{
if (e.Key == Key.Enter)
{
SendMessage();
}
}
#endregion

#region 发送信息
private void btnSend_Click(object sender, RoutedEventArgs e)
{
SendMessage();
}
private void SendMessage()
{
if (this.txtMessage.Text == "")
{
MessageBox.Show("请输入信息！");
return;
}

ChatService.MessageInfo message = new ChatService.MessageInfo();
message.ID = Guid.NewGuid().ToString();
message.Receipt = 0;
message.ReceiveMode = "user";
message.ReceiveOrgan = "";
message.ReceiveUser = this.txtPartner.Text;
message.Message = this.txtMessage.Text;
message.Sender = this.txtMe.Text;
message.SendTime = DateTime.Now;
message.Source = "web";
message.State = 0;
message.Title = this.txtMessage.Text;

proxy = new ChatService.ChatServiceClient(binding, address);
proxy.SendMessageCompleted += new EventHandler<ChatService.SendMessageCompletedEventArgs>(SendMessageComleted);
proxy.SendMessageAsync(message);

this.txtMessage.Text = "";
}
void SendMessageComleted(object sender, ChatService.SendMessageCompletedEventArgs e)
{
if (e.Error == null)
{
//MessageBox.Show(e.Result.ToString());
}
}
#endregion

#region 关闭窗口
private void btnClose_Click(object sender, EventArgs e)
{

}
#endregion
}
}