代码如下：
复制代码 代码如下:
private void button2_Click(object sender, RoutedEventArgs e)
{
Service1Client sc = new Service1Client();
sc.DoWorkCompleted += new EventHandler<DoWorkCompletedEventArgs>(sc_DoWorkCompleted);
sc.DoWorkAsync(textBox1.Text);
}
void sc_DoWorkCompleted(object sender, DoWorkCompletedEventArgs e)
{
textBox2.Text = e.Result;
}

若是你的调用非常复杂的话，比如当这个调用完成的时候开始下一个调用，然后又进行下一个调用，各个调用之间存在关联关系的话，一直XX_DoWorkCompleted会让你头大，并且不利于代码的管理。若碰到过这样的问题的朋友一定很希望如果能够同步调用就好了，这篇文章将帮到你。或者现在不需要，等你需要的时候记得用就行了，别像我当初那样难为的不行。

主要是需要引用一个类库的问题，这个类库是外国人写的，名称为DanielVaughan.dll,下载完之后，首先需要在项目中添加对它的引用，如下图，

然后在程序中添加对两个空间的引用，如下图：

将原来的添加botton1事件：

复制代码 代码如下:
private void button1_Click(object sender, RoutedEventArgs e)
{
string dd = textBox1.Text;
string res = "NULL";
ThreadPool.QueueUserWorkItem(delegate
{
Service1 sv = ChannelManager.Instance.GetChannel<Service1>();
/* Perform synchronous WCF call. */
res = SynchronousChannelBroker.PerformAction<string, string>(sv.BeginDoWork, sv.EndDoWork, dd);
Dispatcher.BeginInvoke(delegate
{
textBox2.Text +="\r\n同步调用--"+ res+"\r\n";
});
});
}

这样就可以实现对WebClient的同步调用了，当你需要关联调用WebClient3次以上的时候 可以考虑使用这个类库，如果只是简单的调用下的话，没有必要使用。
页面全部代码：
复制代码 代码如下:
<UserControl x:Class="SilverlightApplication2.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400" xmlns:dataInput="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Data.Input" Width="640" Height="480">
<Grid x:Name="LayoutRoot">
<Grid.Background>
<LinearGradientBrush EndPoint="0.443,0.621" StartPoint="0.443,-2.509">
<GradientStop Color="#FF5C6768"/>
<GradientStop Color="White" Offset="1"/>
</LinearGradientBrush>
</Grid.Background>
<Button Content="同步调用服务" Height="40" HorizontalAlignment="Left" Margin="67,98,0,0" Name="button1" VerticalAlignment="Top" Width="120" Click="button1_Click" />
<dataInput:Label Height="50" HorizontalAlignment="Left" Margin="67,188,0,0" Name="label2" VerticalAlignment="Top" Width="46" Content="状态：" FontSize="16" />
<TextBox Height="40" HorizontalAlignment="Left" Margin="165,27,0,0" Name="textBox1" VerticalAlignment="Top" Width="300" FontSize="16" />
<TextBox Height="100" HorizontalAlignment="Left" Margin="146,188,0,0" Name="textBox2" VerticalAlignment="Top" Width="400" FontSize="16" TextWrapping="Wrap" Text="尚未调用服务" />
<Button Content="异步调用服务" Height="40" HorizontalAlignment="Left" Margin="346,98,0,0" Name="button2" VerticalAlignment="Top" Width="120" Click="button2_Click" />
<dataInput:Label Height="40" HorizontalAlignment="Left" Margin="67,27,0,0" Name="label1" VerticalAlignment="Top" Width="92" FontSize="16" Content="输入文本：" />
</Grid>
</UserControl>

处理程序全部代码：
复制代码 代码如下:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using SilverlightApplication2.ServiceReference1;
using System.Threading;
using DanielVaughan;
namespace SilverlightApplication2
{
public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
UISynchronizationContext.Instance.Initialize(Dispatcher);
}
private void button1_Click(object sender, RoutedEventArgs e)
{
string dd = textBox1.Text;
string res = "NULL";
ThreadPool.QueueUserWorkItem(delegate
{
Service1 sv = ChannelManager.Instance.GetChannel<Service1>();
/* Perform synchronous WCF call. */
res = SynchronousChannelBroker.PerformAction<string, string>(sv.BeginDoWork, sv.EndDoWork, dd);
Dispatcher.BeginInvoke(delegate
{
textBox2.Text +="\r\n同步调用--"+ res+"\r\n";
});
});
}
private void button2_Click(object sender, RoutedEventArgs e)
{
Service1Client sc = new Service1Client();
sc.DoWorkCompleted += new EventHandler<DoWorkCompletedEventArgs>(sc_DoWorkCompleted);
sc.DoWorkAsync(textBox1.Text);
}
void sc_DoWorkCompleted(object sender, DoWorkCompletedEventArgs e)
{
textBox2.Text += "异步调用--" + e.Result + "\r\n";
}
}
}

Service代码：
复制代码 代码如下:
using System;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Activation;
namespace SilverlightApplication2.Web
{
[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class Service1
{
[OperationContract]
public string DoWork(string aa)
{
// 在此处添加操作实现
return "调用服务完成，返回你输入的值:"+aa;
}
// 在此处添加更多操作并使用 [OperationContract] 标记它们
}
}

详细出处参考：http://www.jb51.net/article/26750.htm