LiveTimer ASP.NET Server Control Information

This page includes information about the LiveTimer Server Control, which is included in PowerWEB LiveControls for ASP.NET: 

[View LiveControl Demo]

The LiveTimer server control is used to periodically poll the server for new data. Set the Interval property and start the timer and a callback is issued to the server, raising the Timer.Tick event. Within this event, take whatever action you wish and update the client UI. All of this client/server communication occurs transparently, without any UI interruption or browser refresh. As a result, a static webpage can become "live": constantly and smoothly updated as new data is available on the server.

Remember! Any LiveControl which raises a callback to the server (such as LiveTimer) raises a server event within which ANY client-side element can be visually updated without refreshing the page!

The LiveTimer control has the following features:

• Cross-browser compatible, no plugins, downloads, or security warnings.
• Intuitive interface has Interval property and Start() and Stop() methods, exactly like Windows Timer.
• Set Interval property to 0 and the Tick event is raised as often as possible (as often as network bandwidth allows), ideal for applications that require data refreshes as close to "real-time" as possible.
• When used in browsers that don't allow remote scripting techniques, the ASP.NET __doPostBack function is called in place of the callback function to periodically issue a standard postback.

Some example uses for LiveTimer:

• Build a web-chat application, using the LiveTimer to constantly poll for new chat messages.
• "Stream" constantly updated data (such as sports scores, stocks, or weather conditions) to the browser.
• Create a web-based email system that checks for new mail and displays messages when it arrives.
• Make an online auction system that updates the current bids in real time.

Browser Compatibility

LiveControls have been tested and are fully "callback-compatible" in the following browsers:

• Microsoft Internet Explorer 5.0+ for Windows
• Microsoft Interner Explorer 5.0+ for Macintosh
• Netscape 7.1+ for Windows
• Netscape 7.1+ for Macintosh OS X
• Mozilla 1.3+ for Windows
• Mozilla 1.3+ for Macintosh OS X
• Firefox for Windows
• Firefox for Macintosh OS X
• Camino for Macintosh OS X
• Konqueror based engines
• Galeon
• Opera 5.0+

If a browser which is not compatible accesses a page containing LiveControls, the controls will fall back to the standard ASP.NET functionality. For example, a LiveButton issues a transparent callback when clicked. If on a non-compatible page, the button will still be displayed, but will cause a standard postback when clicked.

Server Tag Example

The following tags demonstrate typical settings for initializing and starting a LiveTimer

<cc1:LiveTimer id="LiveTimer" runat="server" Interval="100" Enabled="true">
</cc1:LiveTimer>

Code-Behind Example

The LiveTimer is also quite easy to configure/use in Code-Behind.

// Configure and start the timer
LiveTimer1.Interval = 100;
LiveTimer1.Start();

// Tick event raised every 100 milliseconds.
private void LiveTimer1_Tick(object sender, System.EventArgs e)
{
   // update a label with the current time
   LiveLabel1.Text = DateTime.Now.ToLongTimeString();
}