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Understanding AJAX Applications and ASP.NET Atlas (Provided by Microsoft)
AJAX (Asynchronous JavaScript and XML) describes a cross-platform, client-centric approach to developing Web applications. In AJAX, developers use client scripts to make asynchronous calls to Web server applications using an XML-based protocol. The new ASP.NET technology code-named "Atlas" is a package of Microsoft technologies that applies and extends the AJAX approach. This topic describes the Web application development issues that AJAX addresses, explains the basic concepts of AJAX, and introduces ASP.NET "Atlas" as a significant evolution and enhancement of the AJAX approach.
http://beta.asp.net/default.aspx?tabindex=7margin:10px!important;margin:5px;">· The browser's Document Object Model (DOM), which exposes the elements on an HTML page as a standard set of objects (document, window, and so on) that can be manipulated programmatically.· Dynamic HTML (DHTML), which extends HTML with facilities for reacting to user input on the page in client script, without requiring a round trip.· Behaviors, which are a way of programmatically packaging UI actions (such as drag and drop) that can then be associated with page elements.· Components, which are custom JavaScript objects that provide extensive client-side UI features.JavaScript in combination with these client-side technologies enables developers to create a UI with features that can rival those in desktop applications. Two examples of AJAX-style applications are the Microsoft Virtual Earth site and the Microsoft Outlook Web Access e-mail client. Both applications exhibit the extensive UI and high performance that are typical for applications built with this approach. However, using these technologies to create AJAX applications is complex. Until recently developers have had to manually create the event handling, messaging, and other details need to create an extensive UI. Furthermore, because JavaScript is not an object-oriented programming (OOP) language, it does not have strong typing, namespaces, exception handling, and other OOP features. Developers have often had to write their own infrastructure code for features that are built into other languages.ASP.NET "Atlas" Provides a New ApproachASP.NET "Atlas" is Microsoft's answer for how you can harness the power of AJAX applications. ASP.NET "Atlas" provides all the capabilities of AJAX, but extends the concept and significantly reduces the complexity of AJAX development. On the client side, "Atlas" provides an extensive set of script libraries that provide these features:· Object-oriented development. The client libraries add object-oriented features to JavaScript, such as a type system, data types, namespaces, events, and so on. These features give you a familiar programming model and enable you to write higher quality, maintainable, and reusable code. · Browser compatibility. The libraries handle browser compatibility issues automatically, eliminating the need to write browser-specific scripts.· Behaviors and client components. The libraries include commonly used behaviors, including auto-completion, drag and drop, popups, and mouse hovering. They also add components that can be bound to data, which simplifies creating data-driven business applications.· Code for handling remote procedure calls. The libraries manage the complexity of making asynchronous calls over XMLHTTP, reducing a call to just a few lines of scripting code.· Declarative programming model. The libraries enable you to create "Atlas" components using declarative syntax, similar to how you create ASP.NET server controls."Atlas" also includes server components that provide an extensive set of features on the server that complement the "Atlas" client script libraries. The "Atlas" server components include the following:· Web server controls. These ASP.NET server controls emit client script to use "Atlas" features. These controls are useful if you already know server-side development well or if you do not create "Atlas" client scripts manually. · Web services. These are ASP.NET Web services, such as ASP.NET profiles, that can add useful server-side features to an "Atlas" application.http://beta.asp.net/default.aspx?tabindex=7tabid=47 |
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