How to Consume a Web Service in a WPF Application?

Introduction

This article explains how to consume a Web Service in a WPF Windows application. It requires binding of WPF controls to data coming from a Web Service.

The main object participating in the binding process is the DataContext. It is available as a Dependency Property for the WPF Window and most of the WPF Framework Elements. Data context is a concept that allows elements to inherit information from their parent elements about the data source that is used for binding, as well as other characteristics of the binding, such as the path. Data context can be set directly to a Common Language Runtime (CLR) object, with the bindings evaluating to properties of that object. Alternatively, you can set the data context to a DataSourceProvider object. This Dependency Property inherits property values. If there are child elements without other values for DataContext established through local values or styles, then the property system will set the value to be the DataContext value of the nearest parent element with this value assigned.

Creating a Web Service

To demonstrate the purposes of this article, we must first create an ASP.NET Web Service project named “MyWebService” and add a custom class WebContent to the project. This class has a string property, GreetingMessage, and a field Names, a string array.

public class WebContent
{
    string greet;
    public string GreetingString
    {
        get
        {
            return greet;
        }
        set
        {
            greet = value;
        }
    }
    public string[] Names;
}

For convenience, create a Web Service method that sets the values of the properties and return the object of this custom type.

Here is the code for the Web Service definition:

public class Service1 : System.Web.Services.WebService
{

    [WebMethod]
    public WebContent CreateObject()
    {
        WebContent wc = new WebContent();
        wc.GreetingString = "Hello World";
        wc.Names = new string[5] {"Bala", "Murali", 
           "Balaji", "Krish", "Chris" };
        return wc;
    }
}

Build the Web Service project and do the test run to execute the method.

Creating a WPF Window that consumes the Web Service

Now, to consume the Web Service created above in the WPF application, create a new WPF window project and add a few TextBlock and ListBox controls on to the form. To call a Web Service, add a Service Reference from the Project menu and supply the URL (http://localhost/MyWebService/service1.asmx) in the dialog shown.

Create a proxy for the Web Service reference in the OnLoad event handler of the WPF window, and call the CreateObject method as below:

void OnLoad(object sender, RoutedEventArgs e)
{
    WebReference.Service1SoapClient proxy = 
                 new WebReference.Service1SoapClient();
    this.DataContext = proxy.CreateObject();
}

The output of the CreateObject method is of WebContent type and is set as a DataContext for the Window object. Once we do this, all accessible properties of the type are available for binding to different elements in the window.

Now, modify the XAML code with bindings to the properties, as below:

<TextBlock Grid.Column="0" Grid.Row="0" 
  FontWeight="Bold" Text="Greeting Message:"/>
<TextBlock Grid.Column="1" Grid.Row="0" 
  FontWeight="Bold" Text="{Binding Path=GreetingString}"  Foreground="Blue" />
<TextBlock Grid.Column="0" Grid.Row="1" 
  FontWeight="Bold" Text="List of Names: "/>
<ListBox  Grid.Column="1" Grid.Row="1" Margin="0,3,0,0" 
  ItemsSource="{Binding Path=Names}"  Foreground="Blue" />

Build the WPF window project and press F5 to run it.

Conclusion

A Web Service is created and consumed in a WPF window application. The DataContext property can be assigned to the type of the object returned by a Web Service method. This way, properties of any type can be bound to the appropriate WPF elements using Web Service methods.