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). Clients supporting Ajax ASP.NET AJAX runs on the following browsers: Microsoft Internet Explorer (>= 6.0) Mozilla Firefox (>= 1.5) Opera (>= 9.0) Apple Safari (>= 2.0) Google Chrome (>= 5) ASP.NET AJAX Suite At present, the ASP.NET AJAX suite consists of the following components and packages: Microsoft Now Launched Ajax Library 4.0, which supports Data Driven Web Applications. Microsoft Ajax Library 3.5, which is a JavaScript library that provides the client-side features of the ASP.NET AJAX framework. Integrated in ASP.NET 3.5, the library is also available as a separate download for use in other environments, such as PHP. A server framework – included in ASP.NET 3.5 – for building Ajax-enabled ASP.NET server controls. These components are also available for ASP.NET 2.0 in a separate package called ASP.NET AJAX 1.0 Extensions. ASP.NET 2.0 AJAX Templates, a package with a set of Visual Studio templates for building ASP.NET AJAX applications with ASP.NET 2.0 and Visual Studio 2008. ASP.NET AJAX Preview, a package with the new features that will be part of the future versions of the framework. Microsoft Ajax Library The Microsoft Ajax Library is a JavaScript library that provides the features for the client portion of the ASP.NET AJAX framework. Components – The library provides an infrastructure to build either visual or non-visual JavaScript components. A global JavaScript object – SysApplication – is responsible for managing the lifecycle of client components. JavaScript extensions – An enhanced type system is introduced to emulate object-oriented constructs such as namespaces, classes and interfaces; and to perform reflection on client types. Abstraction API – Common operations on the DOM (retrieving elements, setting styles and other manipulations) are automatically translated by the library into browser-specific calls. Ajax – A set of client components is provided to handle Ajax requests and web-service calls. Application Services – The library allows accessing the ASP.NET Membership, Authentication, Roles and Profile services from the client side. Recently, new features have been announced as part of the ASP.NET AJAX 4.0 release: Template Engine – Allows displaying data on the client side by using HTML templates and a custom binding notation. This approach avoids performing page rendering on the server side. Declarative instantiation of client components – Allows registration, instantiation and configuration of client components