Atlas StopableTimer

I tried out the March CTP release of Microsofts new Ajax implementation Atlas. The library now has a "go live" license making it even more interesting for us real life programmers.

The TimerControl included in Atlas March CTP has a problem. It cannot be stopped ones started. I guess that this is intentional (that’s what the documentation says) but the fact remains. You often want to be able to update a page, only while some task is run on the server.

A user on the Atlas forum named Rama Krishna (that’s his username) came up with a clean and great solution to create a stopable timer control (see the post here). However, the posted control only worked on the January CTP release.

I took his control and modified and updated it for the March CTP release (All credit to Rama).

The control emits a client-side timer control (xml) and assigns an id to it. (The base TimerControl does not). Then a small piece of java script is registered to handle enabling and disabling the timer at startup.

First put the following in the App_Code folder:

using System;

using Microsoft.Web.UI.Controls;

 

namespace CustomControls {

 

    public class StopableTimer : TimerControl {

        public StopableTimer() {

        }

 

        protected override void OnPreRender(EventArgs e) {

            base.OnPreRender(e);

            if (Page.IsPostBack) {

              Page.ClientScript.RegisterStartupScript(

          Page.GetType(), "TimerStop",

                    "Sys.Application.findObject('" +

            UniqueID +

            "').set_enabled(" +

            (Enabled ? "true" : "false") +

            ");"

                    , true);

          }

        }

 

        protected override void RenderScript(Microsoft.Web.Script.ScriptTextWriter writer) {

            writer.WriteStartElement("timer");

            writer.WriteAttributeString("id", UniqueID);

            writer.WriteAttributeString("interval",

          Interval.ToString(System.Globalization.CultureInfo.InvariantCulture));

            writer.WriteAttributeString("enabled", Enabled.ToString());

            writer.WriteStartElement("tick");

            writer.WriteStartElement("postBack");

            writer.WriteAttributeString("target", UniqueID);

            writer.WriteAttributeString("eventArgument", string.Empty);

            writer.WriteEndElement();

            writer.WriteEndElement();

            writer.WriteEndElement();

        }

    }

}

When you have created the control, you only need to register it on you aspx page - and use it as you would use a TimerControl

<%@ Register Assembly="App_Code" Namespace="CustomControls" TagPrefix="AppCode" %>