private void addGeoRssLayer(UrlChosenEventArgs e)
        {
            if (e.Url == null)
                return;
            Uri targetUri = null;
            if (!Uri.TryCreate(e.Url, UriKind.Absolute, out targetUri))
            {
                return;
            }
            if (View.Instance != null)
            {

                CustomGeoRssLayer geoRssLayer = new CustomGeoRssLayer()
                {
                    Source = targetUri,
                    ID = Guid.NewGuid().ToString("N"),
                };
                Core.LayerExtensions.SetDisplayUrl(geoRssLayer, e.Url);                
                geoRssLayer.SetValue(ESRI.ArcGIS.Client.Extensibility.MapApplication.LayerNameProperty, targetUri.Host);
                geoRssLayer.MapSpatialReference = View.Instance.Map.SpatialReference;
                geoRssLayer.UpdateCompleted +=new EventHandler(applyAutomaticClustering);
                View.Instance.Map.Layers.Add(geoRssLayer); 
            }
            MapApplication.Current.HideWindow(enterUrlDialog);
            OnUrlChosen(e);
        }
        protected override void WriteAttributes(Layer layer)
        {
            base.WriteAttributes(layer);

            CustomGeoRssLayer geoRssLayer = layer as CustomGeoRssLayer;

            if (geoRssLayer != null)
            {
                base.WriteAttribute("IsItemOnClickBehaviorEnabled", geoRssLayer.IsItemOnClickBehaviorEnabled.ToString());

                if (geoRssLayer.Source != null)
                {
                    writer.WriteAttributeString("Source", geoRssLayer.Source.AbsoluteUri);
                }

                if (geoRssLayer.MapSpatialReference != null)
                {
                    WriteSpatialReferenceAsAttribute(writer, Namespaces, "MapSpatialReference", geoRssLayer.MapSpatialReference);
                }
                if (geoRssLayer.LayerSpatialReference != null)
                {
                    WriteSpatialReferenceAsAttribute(writer, Namespaces, "LayerSpatialReference", geoRssLayer.LayerSpatialReference);
                }
            }
        }