The good news is that Silverlight 2.0 supports Data Binding. However, when I wanted to use it it did not work the way I expected it.

The Problem

Check out this Silverlight 2.0 XAML file:

    xmlns="http://schemas.microsoft.com/client/2007"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Width="400" Height="300">
   
       
       
   

Here is the corresponding code behind:

using System.Windows;
using System.Windows.Controls;
using System.ComponentModel;

namespace SilverlightDataBinding
{
    public partial class Page : UserControl
    {
        public Page()
        {
            DataContext = this;
            SetValue(HelloTextProperty, "Silverlight is cool");

            InitializeComponent();

            ChangeHelloText.Click += new RoutedEventHandler(ChangeHelloText_Click);
        }

        void ChangeHelloText_Click(object sender, RoutedEventArgs e)
        {
            SetValue(HelloTextProperty, HelloText + " cool");
        }

        public string HelloText
        {
            get { return (string)GetValue(HelloTextProperty); }
            set { SetValue(HelloTextProperty, value); }
        }
        public static readonly DependencyProperty HelloTextProperty =
            DependencyProperty.Register("HelloText", typeof(string), typeof(Page), null);
    }
}

If I run this application I can click on the button as often as I want. The content of the TextBlock never changes. However, in Visual Studio I can see that the value of the dependency property HelloText has changed! Seems to be a problem with refreshing the screen appropriately.

A Solution With CLR Objects

I wanted to know if the refresh problem also occurs with CLR objects that implement INotifyPropertyChanged. Therefore I changed the app shown above a little bit and I added a class.

Here is the XAML file after the changes:

    xmlns="http://schemas.microsoft.com/client/2007"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Width="400" Height="300">
   
       
       
       
   

Here is the new class:

using System.ComponentModel;

namespace SilverlightDataBinding
{
    public class TextContainer : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        private string helloText;
        public string HelloText
        {
            get
            {
                return helloText;
            }
            set
            {
                if (helloText != value)
                {
                    helloText = value;
                    if (PropertyChanged != null)
                        PropertyChanged(this, new PropertyChangedEventArgs("HelloText"));
                }
            }
        }
    }
}

Last but not least the code behind file:

using System.Windows;
using System.Windows.Controls;
using System.ComponentModel;

namespace SilverlightDataBinding
{
    public partial class Page : UserControl
    {
        private TextContainer textContainer;

        public Page()
        {
            DataContext = this;
            SetValue(HelloTextProperty, "Silverlight is cool");
            textContainer = new TextContainer();
            textContainer.HelloText = "Silverlight is cool";

            InitializeComponent();

            ChangeHelloText.Click += new RoutedEventHandler(ChangeHelloText_Click);
            TextBlock_CLR.DataContext = textContainer;
        }

        void ChangeHelloText_Click(object sender, RoutedEventArgs e)
        {
            SetValue(HelloTextProperty, HelloText + " cool");
            textContainer.HelloText += " cool";
        }

        public string HelloText
        {
            get { return (string)GetValue(HelloTextProperty); }
            set { SetValue(HelloTextProperty, value); }
        }
        public static readonly DependencyProperty HelloTextProperty =
            DependencyProperty.Register("HelloText", typeof(string), typeof(Page), null);
    }
}

Believe it or not - the CLR class with INotifyPropertyChanged works!

Getting Dependency Properties to Work

Finally I found out that refreshing the screen works correctly with Dependency Properties if the object containing them also implements INotifyPropertyChanged:

using System.Windows;
using System.Windows.Controls;
using System.ComponentModel;

namespace SilverlightDataBinding
{
    public partial class Page : UserControl, INotifyPropertyChanged
    {
        private TextContainer textContainer;

        public event PropertyChangedEventHandler PropertyChanged;

        public Page()
        {
            DataContext = this;
            SetValue(HelloTextProperty, "Silverlight is cool");
            textContainer = new TextContainer();
            textContainer.HelloText = "Silverlight is cool";

            InitializeComponent();

            ChangeHelloText.Click += new RoutedEventHandler(ChangeHelloText_Click);
            TextBlock_CLR.DataContext = textContainer;
        }

        void ChangeHelloText_Click(object sender, RoutedEventArgs e)
        {
            SetValue(HelloTextProperty, HelloText + " cool");
            textContainer.HelloText += " cool";
        }

        public string HelloText
        {
            get { return (string)GetValue(HelloTextProperty); }
            set { SetValue(HelloTextProperty, value); }
        }
        public static readonly DependencyProperty HelloTextProperty =
            DependencyProperty.Register("HelloText", typeof(string), typeof(Page),
            HelloTextChangedCallback);
        public static void HelloTextChangedCallback( DependencyObject d, DependencyPropertyChangedEventArgs e )
        {
            var p = (Page)d;
            if (p.PropertyChanged != null)
                p.PropertyChanged(p, new PropertyChangedEventArgs("HelloText"));
        }
    }
}

I assume that this is a bug in Silverlight 2.0 Beta. Otherwise Silverlight would behave completely different than WPF.