Silverlight 2 Web Service Part I - The Beginning

A proxy to the service should appear under the Service References folder in the Solution Explorer. Click on the Show All Files button in the Solution Explorer to see all the files added to the proxy. There will also be a ServiceReferences.ClientConfig file added to the project root folder. This file configures the connection to the Web Service.

Writing the Web Service code

Now that we have a proxy to the Web Service we can begin to write the logic to handle the calls to the Web Service methods. The first thing we need to do is to add a couple of using statement to the Page.xaml.cs page. The following using statements are needed:

DataService: Makes it easier to access the Web Service classes.

System.Windows.Browser: To gain access to the HtmlPage class needed to get the current port.

System.ServiceModel: To gain access to the EndpointAddress and the BasicHttpBinding classes needed when creating the Web Service proxy object in code. We will override the settings in the ServiceReferences.ClientConfig file. We need to do that to prevent the Web Service from stop working when the port changes.

using WebService.DataService;
using System.Windows.Browser;
using System.ServiceModel;

Code in the Button_Click event

Next we will create an EndpointAddress object to define where the Web Service is located. We do this to ensure that we can call the service even if the port changes. You could change this endpoint address and base the URL on the current Silverlight page so that it will work wherever you deploy it.

private void Button_Click(object sender, RoutedEventArgs e)
{
System.ServiceModel.EndpointAddress endpoint = new
EndpointAddress("http://localhost:" +
HtmlPage.Document.DocumentUri.Port + "/wsData.svc");
}

Next we need to create a proxy object that will handle the call to the service. On the proxy object we will create an event handler for the GetTextCompleted event that will fire when the call returns from the service method call. It is named after the GetText method we created earlier in the Web Service class.

The default time out is 60 seconds, which might be a tad long, so we will change that to 30 seconds using the OperationTimeout property of the proxy object.

All calls to Web Services need to be done asynchronously so we will call the GetTextAsync method on the proxy object. When calling a method asynchronously we need to have a callback method present, in our case it is the GetTextCompleted method.

private void Button_Click(object sender, RoutedEventArgs e)
{
System.ServiceModel.EndpointAddress endpoint = new
EndpointAddress("http://localhost:" +
HtmlPage.Document.DocumentUri.Port + "/wsData.svc");
wsDataClient proxy = new wsDataClient(new BasicHttpBinding(), endpoint);
proxy.GetTextCompleted += new
EventHandler<GetTextCompletedEventArgs>(proxy_GetTextCompleted);
proxy.InnerChannel.OperationTimeout = TimeSpan.FromSeconds(30);
proxy.GetTextAsync();
}

Callback method code

The last thing we need to do is to write the code in the callback method. Let's place the result in the TextBlock called lblResult we added to the Page.xaml page.

void proxy_GetTextCompleted(object sender, GetTextCompletedEventArgs e)
{
try { lblResult.Text = e.Result.ToString(); }
catch { lblResult.Text = "Error calling Web Service"; }
}