Procedura: specificare le credenziali del client per una richiesta del servizio dati (client Silverlight)
È possibile specificare le credenziali utilizzate in fase di esecuzione di una richiesta a un servizio dati che implementa OData (Open Data Protocol). A tale scopo, è necessario effettuare una richiesta tra domini, essere in esecuzione all'esterno del browser oppure impostare in modo esplicito il valore della proprietà HttpStack su ClientHttp. In questi casi vengono utilizzare le credenziali predefinite dalla relativa cache. È inoltre possibile fornire credenziali non predefinite impostando la proprietà UseDefaultCredentials su false e fornendo un oggetto NetworkCredential per la proprietà Credentials dell'oggetto DataServiceContext. Nell'esempio in questo argomento viene illustrato come fornire in modo esplicito le credenziali che vengono utilizzate dal client Silverlight per richiedere i dati dal servizio dati.
Al termine della Guida rapida di WCF Data Services verrà creato il servizio dati Northwind di esempio a cui accede l'applicazione. È inoltre possibile utilizzare il servizio dati Northwind di esempio pubblico, disponibile sul sito Web OData. Questo servizio dati di esempio è di sola lettura e viene restituito un errore se si tenta di salvare le modifiche.
Esempio
L'esempio seguente è tratto dalla pagina code-behind di un file XAML (Extensible Application Markup Language) che rappresenta la pagina principale dell'applicazione Silverlight. In questo esempio viene visualizzata un'istanza di LoginWindow per raccogliere le credenziali di autenticazione dall'utente e utilizzare quindi queste credenziali non predefinite per una richiesta al servizio dati mediante l'implementazione HTTP del client Silverlight.
Imports ClientCredentials.Northwind
Imports System.Data.Services.Client
Imports System.Windows.Data
Imports System.Net
Partial Public Class MainPage
Inherits UserControl
' Create the binding collections and the data service context.
Private binding As DataServiceCollection(Of Customer)
Private context As NorthwindEntities
Private customerAddressViewSource As CollectionViewSource
' Instantiate the service URI and credentials.
Dim serviceUri As Uri = New Uri("https://localhost:54321/Northwind.svc/")
Private credentials As NetworkCredential = New NetworkCredential()
Public Sub Main()
InitializeComponent()
End Sub
Private Sub MainPage_Loaded(ByVal sender As Object, ByVal e As RoutedEventArgs)
' Get credentials for authentication.
Dim login As LoginWindow = New LoginWindow()
AddHandler login.Closed, AddressOf loginWindow_Closed
login.Show()
End Sub
Private Sub loginWindow_Closed(ByVal sender As Object, ByVal e As EventArgs)
Dim userName = String.Empty
Dim domain = String.Empty
Dim password = String.Empty
' Get back the LoginWindow instance.
Dim login As LoginWindow = CType(sender, LoginWindow)
If login.DialogResult = True AndAlso Not login.userNameBox.Text Is String.Empty Then
' Instantiate the binding collection.
binding = New DataServiceCollection(Of Customer)()
' Instantiate the context.
context = New NorthwindEntities(serviceUri)
' Register the LoadCompleted event for the binding collection.
AddHandler binding.LoadCompleted, AddressOf binding_LoadCompleted
' Define an anonymous LINQ query that returns a collection of Customer types.
Dim query = From c In context.Customers
Where c.Country = "Germany"
Select c
' Get the user name and domain from the login.
Dim qualifiedUserName As String() = login.userNameBox.Text.Split(New [Char]() {"\"c})
If qualifiedUserName.Length = 2 Then
domain = qualifiedUserName(0)
userName = qualifiedUserName(1)
Else
userName = login.userNameBox.Text
End If
password = login.passwordBox.Password
' Select the client HTTP stack and set the credentials.
context.HttpStack = HttpStack.ClientHttp
context.UseDefaultCredentials = False
context.Credentials = _
New NetworkCredential(userName, password, domain)
Try
' Execute the query asynchronously.
binding.LoadAsync(query)
Catch ex As Exception
Dim cw = New ChildWindow()
cw.Content = ex.Message
cw.Show()
End Try
ElseIf login.DialogResult = False Then
Dim cw = New ChildWindow()
cw.Content = "Login cancelled."
cw.Show()
End If
End Sub
Private Sub binding_LoadCompleted(ByVal sender As Object, ByVal e As LoadCompletedEventArgs)
If e.Error Is Nothing Then
serviceUriLabel.Content = serviceUri.ToString()
' Load all pages of Customers before binding.
If Not binding.Continuation Is Nothing Then
binding.LoadNextPartialSetAsync()
Else
' Load your data here and assign the result to the CollectionViewSource.
customerAddressViewSource = _
CType(Me.Resources("customerViewSource"), CollectionViewSource)
customerAddressViewSource.Source = binding
End If
Else
' Display the error message from the data service.
Dim cw = New ChildWindow()
cw.Content = e.Error.Message
cw.Show()
End If
End Sub
End Class
using System;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using ClientCredentials.Northwind;
using System.Data.Services.Client;
namespace ClientCredentials
{
public partial class MainPage : UserControl
{
// Create the binding collections and the data service context.
private DataServiceCollection<Customer> binding;
NorthwindEntities context;
CollectionViewSource customerAddressViewSource;
// Instantiate the service URI and credentials.
Uri serviceUri = new Uri("https://localhost:12345/Northwind.svc/");
NetworkCredential credentials = new NetworkCredential();
public MainPage()
{
InitializeComponent();
}
private void MainPage_Loaded(object sender, RoutedEventArgs e)
{
// Get credentials for authentication.
LoginWindow login = new LoginWindow();
login.Closed += new EventHandler(loginWindow_Closed);
login.Show();
}
private void loginWindow_Closed(object sender, EventArgs e)
{
string userName = string.Empty;
string domain = string.Empty;
string password = string.Empty;
// Get back the LoginWindow instance.
LoginWindow login = (LoginWindow)sender;
if (login.DialogResult == true && login.userNameBox.Text != string.Empty)
{
// Instantiate the binding collection.
binding = new DataServiceCollection<Customer>();
// Instantiate the context.
context =
new NorthwindEntities(serviceUri);
// Register the LoadCompleted event for the binding collection.
binding.LoadCompleted += new EventHandler<LoadCompletedEventArgs>(binding_LoadCompleted);
// Define an anonymous LINQ query that returns a collection of Customer types.
var query = from c in context.Customers
where c.Country == "Germany"
select c;
// Get the user name and domain from the login.
string[] qualifiedUserName = login.userNameBox.Text.Split(new char[] {'\\'});
if (qualifiedUserName.Length == 2)
{
domain = qualifiedUserName[0];
userName = qualifiedUserName[1];
}
else
{
userName = login.userNameBox.Text;
}
password = login.passwordBox.Password;
// Select the client HTTP stack and set the credentials.
context.HttpStack = HttpStack.ClientHttp;
context.UseDefaultCredentials = false;
context.Credentials =
new NetworkCredential(userName, password, domain);
try
{
// Execute the query asynchronously.
binding.LoadAsync(query);
}
catch (Exception ex)
{
ChildWindow cw = new ChildWindow();
cw.Content = ex.Message;
cw.Show();
}
}
else if (login.DialogResult == false)
{
ChildWindow cw = new ChildWindow();
cw.Content = "Login cancelled.";
cw.Show();
}
}
private void binding_LoadCompleted(object sender, LoadCompletedEventArgs e)
{
if (e.Error == null)
{
serviceUriLabel.Content = serviceUri.ToString();
// Load all pages of Customers before binding.
if (binding.Continuation != null)
{
binding.LoadNextPartialSetAsync();
}
else
{
// Load your data here and assign the result to the CollectionViewSource.
customerAddressViewSource =
(CollectionViewSource)this.Resources["customerViewSource"];
customerAddressViewSource.Source = binding;
}
}
else
{
// Display the error message from the data service.
ChildWindow cw = new ChildWindow();
cw.Content = e.Error.Message;
cw.Show();
}
}
}
}
Tramite il codice XAML seguente viene definita la pagina principale dell'applicazione Silverlight.
<UserControl x:Class="ClientCredentials.MainPage"
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="https://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="https://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="312" d:DesignWidth="577"
xmlns:sdk="https://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
xmlns:my="clr-namespace:ClientCredentials" Loaded="MainPage_Loaded">
<UserControl.Resources>
<CollectionViewSource x:Key="customerViewSource"
d:DesignSource="{d:DesignInstance my:Northwind.Customer, CreateList=True}" />
</UserControl.Resources>
<Grid x:Name="LayoutRoot" Background="White" DataContext="" Height="312" Width="577"
VerticalAlignment="Top" HorizontalAlignment="Left">
<Grid.RowDefinitions>
<RowDefinition Height="203*" />
<RowDefinition Height="119*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="336*" />
</Grid.ColumnDefinitions>
<sdk:DataGrid AutoGenerateColumns="False" Height="213" HorizontalAlignment="Left"
ItemsSource="{Binding Source={StaticResource customerViewSource}}"
Name="customerDataGrid" RowDetailsVisibilityMode="VisibleWhenSelected"
VerticalAlignment="Top" Width="553" Margin="12,44,0,0"
Grid.RowSpan="2" Grid.ColumnSpan="1">
<sdk:DataGrid.Columns>
<sdk:DataGridTextColumn x:Name="customerIDColumn" Binding="{Binding Path=CustomerID}"
Header="Customer" Width="80" />
<sdk:DataGridTextColumn x:Name="addressColumn" Binding="{Binding Path=Address}"
Header="Address" Width="180" />
<sdk:DataGridTextColumn x:Name="cityColumn" Binding="{Binding Path=City}"
Header="City" Width="120" />
<sdk:DataGridTextColumn x:Name="countryColumn" Binding="{Binding Path=Country}"
Header="Country" Width="80" />
<sdk:DataGridTextColumn x:Name="postalCodeColumn" Binding="{Binding Path=PostalCode}"
Header="Postal Code" Width="90" />
<sdk:DataGridTextColumn Binding="{Binding Path=CompanyName}" Header="CompanyName" />
<sdk:DataGridTextColumn Binding="{Binding Path=ContactName}" Header="ContactName" />
<sdk:DataGridTextColumn Binding="{Binding Path=Phone}" Header="Phone" />
</sdk:DataGrid.Columns>
</sdk:DataGrid>
<sdk:Label Grid.Row="0" Grid.Column="0" Height="26" HorizontalAlignment="Left" Margin="16,12,0,0"
Name="serviceUriLabel" VerticalAlignment="Top" Width="550" />
</Grid>
</UserControl>
L'esempio seguente è tratto dalla pagina code-behind per l'oggetto ChildWindow utilizzato per raccogliere le credenziali di autenticazione dall'utente prima di effettuare una richiesta al servizio dati.
Imports System.ComponentModel
Partial Public Class LoginWindow
Inherits ChildWindow
Public Sub New()
InitializeComponent()
End Sub
Private Sub OKButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs) Handles OKButton.Click
Me.DialogResult = True
End Sub
Private Sub CancelButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs) Handles CancelButton.Click
Me.DialogResult = False
End Sub
Private Sub LoginWindow_Closing(ByVal sender As System.Object, ByVal e As CancelEventArgs)
If Me.DialogResult = True AndAlso _
(Me.userNameBox.Text = String.Empty OrElse Me.passwordBox.Password = String.Empty) Then
e.Cancel = True
Dim cw As ChildWindow = New ChildWindow()
cw.Content = "Please enter name and password or click Cancel."
cw.Show()
End If
End Sub
End Class
using System;
using System.Windows;
using System.Windows.Controls;
using System.ComponentModel;
namespace ClientCredentials
{
public partial class LoginWindow : ChildWindow
{
public LoginWindow()
{
InitializeComponent();
}
private void OKButton_Click(object sender, RoutedEventArgs e)
{
this.DialogResult = true;
}
private void CancelButton_Click(object sender, RoutedEventArgs e)
{
this.DialogResult = false;
}
private void LoginWindow_Closing(object sender, CancelEventArgs e)
{
if (this.DialogResult == true &&
(this.userNameBox.Text == string.Empty || this.passwordBox.Password == string.Empty))
{
e.Cancel = true;
ChildWindow cw = new ChildWindow();
cw.Content = "Please enter name and password or click Cancel.";
cw.Show();
}
}
}
}
Tramite il codice XAML seguente viene definita la finestra di accesso, ovvero un oggetto ChildWindow dell'applicazione Silverlight.
<controls:ChildWindow x:Class="ClientCredentials.LoginWindow"
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
xmlns:controls="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls"
Width="400" Height="200"
Title="LoginWindow" xmlns:sdk="https://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk" Closing="LoginWindow_Closing">
<StackPanel Name="LayoutRoot" Orientation="Vertical" VerticalAlignment="Top">
<StackPanel Orientation="Horizontal">
<TextBlock Height="25" HorizontalAlignment="Left" Margin="10,20,0,0" Name="userNameLabel" VerticalAlignment="Top"
Width="80" Text="User name:"/>
<TextBox Height="23" HorizontalAlignment="Left" Margin="10,20,0,0" Name="userNameBox" VerticalAlignment="Top"
Width="150" Text="DOMAIN\login"/>
</StackPanel>
<StackPanel Orientation="Horizontal" VerticalAlignment="Top">
<TextBlock Height="25" HorizontalAlignment="Left" Margin="10,20,0,0" Name="pwdLabel" Width="80" Text="Password:"/>
<PasswordBox Height="23" HorizontalAlignment="Left" Margin="10,20,0,0" Name="passwordBox" Width="150" />
</StackPanel>
<StackPanel Orientation="Horizontal" HorizontalAlignment="Right" Height="80" VerticalAlignment="Top">
<Button x:Name="CancelButton" Content="Cancel" Click="CancelButton_Click" Width="75" Height="23"
HorizontalAlignment="Right" Margin="8" />
<Button x:Name="OKButton" Content="OK" Click="OKButton_Click" Width="75" Height="23"
HorizontalAlignment="Right" Margin="8" />
</StackPanel>
</StackPanel>
</controls:ChildWindow>
Protezione
Le considerazioni sulla sicurezza riportate di seguito si applicano all'esempio di questo argomento:
Per verificare le credenziali fornite in questo esempio, il servizio dati Northwind deve utilizzare uno schema di autenticazione diverso dall'accesso anonimo. In caso contrario, il sito Web che ospita il servizio dati non richiederà le credenziali.
Le credenziali utente devono essere richieste solo durante l'esecuzione e non devono essere memorizzate nella cache. Le credenziali devono essere archiviate sempre in modo protetto.
I dati inviati con l'autenticazione di base o digest non sono crittografati, pertanto possono essere visti da un avversario. Le credenziali di autenticazione di base (nome utente e password) inoltre vengono inviate in testo non crittografato e possono essere intercettate.
Vedere anche
Concetti
Creazione di applicazioni Silverlight (WCF Data Services)