Monday, December 15, 2008

Silverlight ConfigurationManager

by Michael Wolf via Michael Wolf on 12/15/2008 1:24:11 PM

A problem I hear rumble up from a lot of .Net developers when picking up Silverlight is, “where is ?” My normal answer is, “If it’s not there, do what Microsoft would do… Make your own.” A perfect example of this would be runtime configuration. With the full CLR, so many of us have become accustomed to using ConfigurationManager that reverting to hard-coding values in the binary pains us. By default, Silverlight embeds the ServiceReferences.ClientConfig for service references into the xap, but usually we would prefer to change our service references in our app.config files from our development deployments to production deployments. To overcome this common problem, we have built our own ConfigurationManager.



In the example above, the text is being loaded using the following config file living on the web server

<?xml version="1.0" encoding="utf-8" ?>
<Configuation>
  <AppSettings>
    <Add Key="title" Value="Hello World from configuration manager"></Add>
  </AppSettings>
</Configuation>

        public static void LoadConfig()
        {
            WebClient client = new WebClient();
            client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(client_DownloadStringCompleted);
            client.DownloadStringAsync(new Uri("app.xml", UriKind.Relative));
        }

        public static void client_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
        {

            if (e.Error!=null)
            {
                throw e.Error;
            }

            // load the data
            XDocument config = XDocument.Parse(e.Result);
            var appsettings = from x in config.Descendants("AppSettings").Descendants("Add")
                              select new AppSettings { Key = (string)x.Attribute("Key"), Value = x.Attribute("Value").Value };

            _appSettings = new Dictionary();
            // add to collection
            if (appsettings.Count() > 0)
            {
                foreach (AppSettings y in appsettings)
                {
                    _appSettings[y.Key] = y.Value;
                }
            }

            // notify that its available
            if (ConfigurationAvailable != null)
                ConfigurationAvailable(null, new EventArgs());
        }

        void Page_Loaded(object sender, RoutedEventArgs e)
        {
            lblHelloWorld.Text = ConfigurationManager.AppSettings["title"];
        }

       private void Application_Startup(object sender, StartupEventArgs e)
        {
            ConfigurationManager.LoadConfig();
            this.RootVisual = new Masterpage();
        }

        void Masterpage_Loaded(object sender, RoutedEventArgs e)
        {
            ConfigurationManager.ConfigurationAvailable += new EventHandler(ConfigurationManager_ConfigurationAvailable);
            LayoutRoot.Children.Add(new Loading());
        }