Silverlight has built-in support for communicating with Web services. This QuickStart provides an introduction to using Web services in Silverlight.

This QuickStart contains the following sections:

Building a Service for a Silverlight Client

To understand Web services, it is helpful to start with a simple example. The example Web service used in this QuickStart is named CustomerService. This service provides customer information to a business. The information includes the number of customers, customer name, customer age, and whether the customer is a member.

The following code show the CustomerService contract in CustomerService.scv.cs (CustomerService.scv.vb). The CustomerService contract contains two operations that a Silverlight client can access. The CountUsers operation returns the number of customers. The GetUser operation returns the customer's name, age, and whether he is a member. GetUser returns a User type, which is defined and implemented as part of the contract.

C#

using System;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Activation;
using System.Collections.Generic;
using System.Text;

namespace SilverlightApplication1Web
{
    [ServiceContract(Namespace = "")]
    [AspNetCompatibilityRequirements
        (RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
    public class CustomerService
    {
        [OperationContract]
        public int CountUsers()
        {
            return 2;
        }
        [OperationContract]
        public User GetUser(int id)
        {
            if (id == 1)
            {
                return new User() { IsMember = true, Name = "Paul", Age = 24 };
            }
            else
            {
                return new User() { IsMember = false, Name = "John", Age = 64 };
            }
        }
    }

    [DataContract]
    public class User
    {
        [DataMember]
        public bool IsMember { get; set; }

        [DataMember]
        public string Name { get; set; }

        [DataMember]
        public int Age { get; set; }
    }

}

Visual Basic

Imports System 
Imports System.Linq 
Imports System.Runtime.Serialization 
Imports System.ServiceModel 
Imports System.ServiceModel.Activation 
Imports System.Collections.Generic 
Imports System.Text 

Namespace SilverlightApplication1Web 
    <ServiceContract([Namespace] := "")> _ 
    <AspNetCompatibilityRequirements _
        (RequirementsMode := AspNetCompatibilityRequirementsMode.Allowed)> _ 
    Public Class CustomerService 
        <OperationContract> _ 
        Public Function CountUsers() As Integer 
            Return 2 
        End Function 
        <OperationContract> _ 
        Public Function GetUser(id As Integer) As User 
            If id = 1 Then 
                Return New User() 
            Else 
                Return New User() 
            End If 
        End Function 
    End Class 
    
    <DataContract> _ 
    Public Class User 
        <DataMember> _ 
        Public Property IsMember() As Boolean 
            Get 
            End Get 
            Set 
            End Set 
        End Property 
        
        <DataMember> _ 
        Public Property Name() As String 
            Get 
            End Get 
            Set 
            End Set 
        End Property 
        
        <DataMember> _ 
        Public Property Age() As Integer 
            Get 
            End Get 
            Set 
            End Set 
        End Property 
    End Class    
End Namespace 

 

Accessing a Service from a Silverlight Client

In Silverlight, you communicate with a Web service through a proxy. You can generate a proxy with a tool, such as Add Service Reference in Visual Studio 2008. The proxy is generated by using the metadata that the service makes available. The metadata describes its functionality and how to access this functionality. The following illustrations show the communication between components. The arrows going to the right represent method calls from the client. The arrows going to the left represent return values from the service.

Because all Web service calls in Silverlight are asynchronous, the proxy contains two members for each operation in the service: an asynchronous method and a completed event. For example, consider the CountUsers service operation in the CustomerService service. You add an EventHandler to the CountUsersCompleted event. This event is invoked when the service returns the requested data. After the event is set up, you can make a call to the service by calling CountUsersAsync. The event handler specifies that the proxy_CountUsersCompleted method is called when the service returns some data. Similar remarks apply to the GetUsers operation.

The following code shows the Page.xaml.cs (or Page.xaml.vb) file for the Silverlight client.

C#

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 SilverlightApplication1.ServiceReference1;


namespace SilverlightApplication1
{
    public partial class Page : UserControl
    {
        public Page()
        {
            // Required to initialize variables
            InitializeComponent();
        }
        void OnClick(object sender, EventArgs args)
        {
            CustomerServiceClient proxy = new CustomerServiceClient();

            proxy.CountUsersCompleted += new
                EventHandler<CountUsersCompletedEventArgs>(proxy_CountUsersCompleted);
            proxy.CountUsersAsync();

            proxy.GetUserCompleted += new
                EventHandler<GetUserCompletedEventArgs%gt;(proxy_GetUserCompleted);
            proxy.GetUserAsync(1);
        }

        void proxy_GetUserCompleted(object sender, GetUserCompletedEventArgs e)
        {
            getUserResult.Text = "Property values of user with ID = 1 are: Name:" + 
                e.Result.Name + ", Age:" + e.Result.Age + ", IsMember:" + 
                e.Result.IsMember;
        }

        void proxy_CountUsersCompleted(object sender, CountUsersCompletedEventArgs e)
        {
            userCountResult.Text = "The number of users is: " + e.Result;
        }
    }
} 

Visual Basic

Imports System 
Imports System.Collections.Generic 
Imports System.Linq 
Imports System.Net 
Imports System.Windows 
Imports System.Windows.Controls 
Imports System.Windows.Documents 
Imports System.Windows.Input 
Imports System.Windows.Media 
Imports System.Windows.Media.Animation 
Imports System.Windows.Shapes 
Imports SilverlightApplication1.ServiceReference1 


Namespace SilverlightApplication1 
    Public Partial Class Page 
        Inherits UserControl
         
        Public Sub New() 
            ' Required to initialize variables 
            InitializeComponent() 
        End Sub
        
        Private Sub OnClick(sender As Object, args As EventArgs) 
            Dim proxy As New CustomerServiceClient() 
            
            proxy.CountUsersCompleted += New _
                EventHandler(Of CountUsersCompletedEventArgs)(proxy_CountUsersCompleted) 
            proxy.CountUsersAsync() 
            
            proxy.GetUserCompleted += New _
                EventHandler(Of GetUserCompletedEventArgs)(proxy_GetUserCompleted) 
            proxy.GetUserAsync(1) 
        End Sub 
        
        Private Sub proxy_GetUserCompleted(sender As Object, _
            e As GetUserCompletedEventArgs) 
            getUserResult.Text = "Property values of user with ID = 1 are: Name:" + _
                e.Result.Name + ", Age:" + e.Result.Age + ", IsMember:" + _
                e.Result.IsMember 
        End Sub 
        
        Private Sub proxy_CountUsersCompleted(sender As Object, _
            e As CountUsersCompletedEventArgs) 
            userCountResult.Text = "The number of users is: " + e.Result 
        End Sub 
    End Class 
End Namespace 

The following XAML from Page.xaml shows how to initiate access to the CustomerService service and display the results. The return values for CountUsers and GetUser are displayed in two TextBlock controls.

XAML

<UserControl x:Class="SilverlightApplication1.Page"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    Width="600" Height="110">
    <Grid x:Name="LayoutRoot" ShowGridLines="True" Background="White">
        <Grid.RowDefinitions>
            <RowDefinition Height="60"/>
            <RowDefinition Height="25"/>
            <RowDefinition Height="25"/>
        </Grid.RowDefinitions>
        <Button
            Grid.Row="0"
            Margin=" 5"
            Height="50"
            Content="Click Here to Access the Web Service"
            Click="OnClick"/>
            <TextBlock Text="The number of users." 
                       x:Name="userCountResult" 
                       Grid.Row="1"/>
            <TextBlock Text="Property values of user with ID = 1." 
                       x:Name="getUserResult"  
                       Grid.Row="2"/>
    </Grid>
</UserControl>

CountUsers and GetUser return the following data.

• The number of users is: 2.
• Property values of user with ID = 1 are: Name:Paul, Age:24, IsMember:True

The following illustration shows an example of the output after clicking the Click Here to Access the Web Service button.

See Also

• Accessing Web Services in Silverlight