|Initial release||January 23, 2007|
|Operating system||Microsoft Windows, Linux, macOS|
|License||Microsoft Public License|
ASP.NET AJAX, formerly called Atlas, is a set of extensions to ASP.NET developed by Microsoft for implementing Ajax functionality. It is released under the Microsoft Public License (Ms-PL).
ASP.NET AJAX runs on the following browsers:
At present, the ASP.NET AJAX suite consists of the following components and packages:
Recently, new features have been announced as part of the ASP.NET AJAX 4.0 release:
The UpdatePanel is an ASP.NET server control that updates portions of a web page without reloading it. Through a mechanism called asynchronous postback, the HTML for the region of the page wrapped by the control is sent by the server asynchronously through an Ajax request. The ASP.NET controls that have been specified as content in an UpdatePanel are able to cause either synchronous (traditional) or asynchronous postbacks, by means of triggers.
A trigger is an event coming from an ASP.NET control that causes an UpdatePanel to refresh its contents. Through triggers, an asynchronous postback can be started also by controls that are declared outside the region of the ASP.NET page wrapped by the UpdatePanel control.
In the following code, only the content of the Update control (the span element that displays the current date and time) is re-rendered every time the button is clicked.
<asp:Button ID="Button1" runat="server" Text="Refresh" /> <asp:UpdatePanel ID="UpdatePanel1" runat="server"> <Triggers> <asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" /> </Triggers> <ContentTemplate> <span><%= DateTime.Now %></span> </ContentTemplate> </asp:UpdatePanel>