using (ServerManager serverManager = new ServerManager())
    {
        foreach (var site in serverManager.Sites)
        {
            var siteNode = new TreeViewItem() { Header = string.Format("Site: {0}", site.Name) };
            _irv.trvIisInformation.Items.Add(siteNode);
            foreach (var application in site.Applications)
            {
                var appPoolNode = new TreeViewItem() { Header = string.Format("AppPool: {0}, Type: {1}", application.ApplicationPoolName, HoleApplikationstyp(serverManager, application)) };
                siteNode.Items.Add(appPoolNode);

                foreach (var virtDir in application.VirtualDirectories)
                {
                    appPoolNode.Items.Add(new TreeViewItem() { Header = string.Format("Dir: {0} [{1}]", virtDir.Path, virtDir.PhysicalPath) });
                }
            }
        }
    }