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

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

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

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：

代码
Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--><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：

<?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。

<UserControl
x:Class="ChatSL.Chat"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation%22

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml%22

xmlns:d="http://schemas.microsoft.com/expression/blend/2008%22

xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006%22

mc:Ignorable="d"

d:DesignHeight="510" d:DesignWidth="514">

<Grid
x:Name="LayoutRoot" Background="White" Height="479"
Width="485">

<TextBox
Height="87" HorizontalAlignment="Left" Margin="12,347,0,0"
Name="txtMessage" VerticalAlignment="Top" Width="335" />

<Button
Content="发送" Height="29" HorizontalAlignment="Right"
Margin="0,440,138,0" Name="btnSend" VerticalAlignment="Top"
Width="61"/>

<ListBox
Height="317" HorizontalAlignment="Left" ItemsSource="{Binding
MessageInfo,Mode=OneWay}" Name="listMsgs" VerticalAlignment="Top"
Width="335" Margin="12,12,0,0">

<ListBox.ItemTemplate>

<DataTemplate>

<StackPanel
Orientation="Horizontal">

<TextBlock
Text="{Binding SendTime,StringFormat='HH:mm:ss'}"
></TextBlock>

<TextBlock
Text=" " ></TextBlock>

<TextBlock
Text="{Binding Sender}" Width="60"></TextBlock>

<TextBlock
Text=" : " ></TextBlock>

<TextBlock
Text="{Binding Message}" FontSize="12"
FontFamily="Verdana" Foreground="Chocolate"></TextBlock>

</StackPanel>

</DataTemplate>

</ListBox.ItemTemplate>

</ListBox>

<Image
Height="31" HorizontalAlignment="Left" Source="Images/online.jpg"
Margin="351,12,0,0" Name="image1" Stretch="Fill"
VerticalAlignment="Top" Width="32" />

<Button
Content="关闭" Height="29" HorizontalAlignment="Left"
Margin="219,440,0,0" Name="btnClose" VerticalAlignment="Top"
Width="61" />

<TextBox
Height="23" HorizontalAlignment="Left" Margin="389,17,0,0"
Name="txtPartner" VerticalAlignment="Top" Width="83" />

<Image
Height="28" HorizontalAlignment="Left" Margin="352,347,0,0"
Name="image2" Source="Images/online.jpg" Stretch="Fill"
VerticalAlignment="Top" Width="31" />

<TextBox
Height="23" HorizontalAlignment="Left" Margin="389,349,0,0"
Name="txtMe" VerticalAlignment="Top" Width="83" />

</Grid>

</UserControl>

后台代码中需要从HTML中接收聊天对象:

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

}

}

效果图：

源代码（包含视频部分）：http://files.cnblogs.com/wengyuli/Chat_%e5%8f%8c%e5%b7%a5http.7z