// Controller will be executed only on HTTP GET request like http://mysite.com/about
[Get("about")]
public class AboutController : Controller
{
    public override ControllerResponse Invoke()
    {
        // About.tpl content will be inserted into {MainContent} in Master.tpl
        return new StaticTpl("Static/About", StringTable.PageTitleAbout);
    }
}

// Controller will be executed on any request and will be launched before other controllers (because they have Priority = 0 by default)
[Priority(-1)]
public class LoginPanelController : AsyncController
{
    public override async Task<ControllerResponse> Invoke()
    {
        return Context.Context.Authentication.User == null
            // Data from GuestPanel.tpl will be inserted into {LoginPanel} in Master.tpl
            ? new InlineTpl("LoginPanel", await TemplateFactory.LoadAsync("Shared/LoginPanel/GuestPanel"))
            // Data from LoggedUserPanelView will be inserted into {LoginPanel} in Master.tpl
            : new InlineTpl("LoginPanel", await GetView<LoggedUserPanelView>().Get(Context.Context.Authentication.User.Identity.Name));
    }
}

public class LoggedUserPanelView : View
{
    public async Task<ITemplate> Get(string userName)
    {
        // Loading template from LoggedUserPanel.tpl asynchronously
        var tpl = await TemplateFactory.LoadAsync("Shared/LoginPanel/LoggedUserPanel");

        // Setting userName into {UserName} variable in LoggedUserPanel.tpl
        tpl.Add("UserName", userName);

        return tpl;
    }
}