（原创）Silverlight远程调用WCF

2.1 跨域问题

就是WCF提供服务，Silverlight消费服务。如果WCF提供的address，比如是http:/localhost:8839/，而Silverlight运行的端口不一致，比如是http:/localhost:7777/，就不是在同一个域中，这时就出现跨域访问的问题。

解决方法：

在WCF服务的根目录下，创建一个clientaccesspolicy.xml文件，文件内容为：

<access-policy>
<cross-domain-access>
<policy>
<allow-from http-request-headers="*">
<domain uri="*"/>
</allow-from>
<grant-to>
<resource path="/" include-subpaths="true"/>
</grant-to>
</policy>
</cross-domain-access>
</access-policy>

项目架构



注:这里创建的xml文件，要放在C:\Inetpub\wwwroot下，用于IIS发布。

只是加了这个文件还不行，还要将这个作为服务来提供。

第一种方案是，在原有的服务接口中增加该服务接口，及该服务的实现方法，尝试了这种方案，问题未得到解决；

第二种方案是，在服务器端新添加WCF服务，取名“PolicyRetriever.vb”，同时自动生成相应的接口，I PolicyRetriever.vb，如上图所示。

接口代码：

<OperationContract()> _
<WebGet(UriTemplate:="ClientAccessPolicy.xml")> _
Function ProvidePolicyFile() As System.ServiceModel.Channels.Message

注：这里用到WebGet的方法，要在IPolicyRetriever.vb中，添加引用：

Imports System.ServiceModel.Web

接口实现代码：

Public Function ProvidePolicyFile() As System.ServiceModel.Channels.Message Implements IPolicyRetriever.ProvidePolicyFile
Dim filestream As FileStream = File.Open("C:\Inetpub\wwwroot\clientaccesspolicy.xml", FileMode.Open, FileAccess.Read, FileShare.ReadWrite)   '此处访问xml地址
Dim reader As XmlReader = XmlReader.Create(filestream)
Dim result As System.ServiceModel.Channels.Message = Message.CreateMessage(MessageVersion.None, "", reader)
Return result
End Function

注：

因为用到FileStream，故要添加引用：

Imports System.IO

因为用到XmlReader，故要添加引用：

Imports System.Xml

因为用到Message，故要添加引用：

Imports System.ServiceModel.Channels

关键部分：

App.Config中，需要修改的地方是：

<behaviors>

<endpointBehaviors>

<behavior name="WebHttpNewBehavior">

<webHttp />

</behavior>

</endpointBehaviors>

</behaviors>

<service behaviorConfiguration="Boolean_Server_Host_1.MP3_BroadServiceBehavior"

name="Boolean_Server_Host_1.MP3_BroadService">

<endpoint address="" binding="basicHttpBinding" bindingConfiguration=""

contract="Boolean_Server_Host_1.IMP3_BroadService">

<identity>

<dns value="localhost" />

</identity>

</endpoint>

<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />

<host>

<baseAddresses>

<add baseAddress="http://10.3.11.169:8731/MP3_BroadService/" />

</baseAddresses>

</host>

</service>

<service behaviorConfiguration="Boolean_Server_Host_1.PolicyRetrieverBehavior"

name="Boolean_Server_Host_1.PolicyRetriever">

<endpoint address="" behaviorConfiguration="WebHttpNewBehavior" binding="webHttpBinding" contract="Boolean_Server_Host_1.IPolicyRetriever">

<identity>

<dns value="localhost" />

</identity>

</endpoint>

<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />

<host>

<baseAddresses>

<add baseAddress="http://10.3.11.169:8731/" />

</baseAddresses>

</host>

</service>

注：上述红色部分是需要添加及修改的地方！

注：开启服务按钮事件中，也要将该服务开启

至此，当服务开启后，在浏览器中输入http://10.3.11.169:8731/clientaccesspolicy.xml

若能看到该xml的内容，就说明跨域问题得到解决。

2.2 以开启和关闭紧急广播为类

第一步：在MainPage.xml中添加两个Button，分别为“开启紧急广播”和“关闭紧急广播”，代码如下：

<Grid x:Name="LayoutRoot" Background=" #46461F">
<Button x:Name="Button_1" Content="开启紧急广播"
FontSize=" 24" Foreground="#FF0046FF"  Click="Button_1_Click" Margin="66,240,0,200" Width="150" Height="40" RenderTransformOrigin="-0.94,-2.2" HorizontalAlignment="Left" d:LayoutOverrides="Width" >
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0"/>
<GradientStop Color="White" Offset="1"/>
<GradientStop Color="#FF3D3D3D" Offset="0.241"/>
</LinearGradientBrush>
</Button.Background>
</Button>

<Button x:Name="Button_2" Content="关闭紧急广播"
FontSize=" 24" Foreground="#FF0046FF"  Click="Button_2_Click" Margin="66,328,0,112" Width="150" Height="40" RenderTransformOrigin="-0.94,-2.2" HorizontalAlignment="Left" d:LayoutOverrides="Width" >
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0"/>
<GradientStop Color="White" Offset="1"/>
<GradientStop Color="#FF3D3D3D" Offset="0.241"/>
</LinearGradientBrush>
</Button.Background>
</Button>
</Grid>

第二步：添加服务引用

第三步：按钮的点击事件（关键）

'*****************************************开启紧急广播功能******************************'
Private Sub Button_1_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
AddHandler proxy.AlarmSpeechCompleted, AddressOf AlarmSpeech_Completed  '事件捆绑
proxy.AlarmSpeechAsync()
End Sub

Private Sub AlarmSpeech_Completed(ByVal sender As Object, ByVal e As MP3_Broad_Service.AlarmSpeechCompletedEventArgs)                                '捆绑事件
MessageBox.Show(e.Result)
End Sub

'*****************************************关闭紧急广播功能******************************'
Private Sub Button_2_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
AddHandler proxy.AlarmSpeech_GuanCompleted, AddressOf AlarmSpeech_Guan_Completed'事件捆绑
proxy.AlarmSpeech_GuanAsync()
End Sub

Private Sub AlarmSpeech_Guan_Completed(ByVal sender As Object, ByVal e As MP3_Broad_Service.AlarmSpeech_GuanCompletedEventArgs)                             '捆绑事件
MessageBox.Show(e.Result)
End Sub