Why a framework?
Actually, this framework is the Ajax engine described by J. J. Garrett and
intended to suppress waiting for the user when accessing the server.
The framework provides classical, cross-browser functions to use the XMLHttpRequest object. But a framework may goes beyond that, and allow to build "rich web applications", applications with a graphical user interface and other features of desktop software that run through a browser, while exchanging data with a remote server.
Features of an Ajax framework
Any Ajax framework is able to communicate with the server, and thus, to read
data or to send it data or commands. In the last case a server-side script
The frameworks often add components that make use of the asynchronous communication with the server.
The classical examples are buttons, tabbed panels, grids, listboxs and other such widgets.
A more innovative example, the "boxes", are more and more often implemented, and Lightbox and Slimbox are two of them. There are image galleries that place them side by side on the screen and that are making use of Ajax to display them instantanously .
Framework may be server-driven also, and in this case, component are created on the server with a scripting language such as PHP, and sent to the browser. Ajax is used to transmit user actions to the server part, and to handle the results.
The ability to work offline as it is offered by HTML 5 is a complement to the Ajax framework as well.
What Ajax framework to choose?
You want to use an Ajax framework to make dynamic pages without having to rewrite the whole stuff youself and test it on all browsers...
But they are so numerous that you wonder which one to use. You want not make a bad choise and be forced later to redo all the pages with a different framework!
You are less likely to regret the choice of a framework if you adopt one of the most used because they are continually supplemented by new extensions and have a good support by users.
Among these, there are jQuery, well documented, Mootools that is modular, Ext JS offering many widgets for RIA.
The interaction with a server side language also should guide the choice.
no server components and therefore server technology dependencies.
Most of them use XML as data format, and sometime JSON, another textual format.
This tag includes the "prototype" library into the page and its
function become usable by the browser, in this page.
Such Ajax libraries and frameworks include:
jQuery provides the most complete documentation. The version 1.3.2 is two times faster than previous one. It has full access to the DOM.
It is used by default by the Wordpress CMS.
jQuip is a more modular version of JQuery with only 4k for the core code.
- Closure Library.
Is the base of several other frameworks including that of Yahoo. Its goal seems to be in reducing the size of Ajax Code.
- Script Aculous.
One of the first frameworks, Script Aculous soon developed many dynamic and graphics effects to liven up Web pages.
Libraries from latest competitors are better optimized.
Based also on prototype, add special effects to HTML pages.
Another toolkit as JQuery, includes graphical effects.
Mootools has features similar to jQuery. It is modular. Many extensions provide graphical widgets such as Lightbox, image galleries ...
Dedicated to rich web applications, the RIAs, Ext JS has many plugins and user interface components, the widgets.
- Dojo Toolkit.
Uses packages with a mechanism to load them together along with the page. It can build reusable components and widgets, a lot of them is provided on the site. It allows to manipulate the DOM more easily, and to make graphical effects.
Includes advanced cross-browser layout managers and an advanced build system for graphical user interfaces similar to that of desktop software. Widgets are provided with the function to use them from the keyboard or the mouse. Third parties provide PHP or Java code to process data with XMLHttpRequest.
- Yahoo UI.
Library from the Yahoo search engine. Includes CSS resources. It is like jQuery UI a set of widget on top of a low-level framework.
A simple library for GET and POST with callbacks. Implements responseHTML, the A.E.P. extension.
On the server side, the programmer may use PHP functions to process requests from the browser. PHP allows to deal with database, search data, build pages or parts of page and publish the page or return data to the XMLHttpRequest object. PHP 5 specifically, thanks to its SimpleXML class, is able to create XML files that may be returned to the object. But all these tasks require special functions to write... however the work is already done in some free open source frameworks.
A small PHP 5 class.
Java is the programming language that is the more often used to build web
A Java framework permit to use Java web services interactively with a web page.
The more commonly used are:
- DWR (Direct
Legacy Java software for the web now is moving to Ajax. JavaServer Faces now includes Ajax features. ThinWire takes a unique approach in that the application is written as if it was a desktop software. All the logic executes on the server, the framework encapsulates the web rendering and communication layers.
- Microsoft Ajax Library (formerly ATLAS) is made of a client side part: Microsoft AJAX Library, and a server side part: ASP.NET 2.0 Ajax Extensions. But a component library is also provided with graphical widgets: ASP.NET Ajax Control Toolkit.
- Ajax.NET Professional "serializes" (converts and stores) .NET data to the JSON format.
Ajax and XUL
The two systems work on the Firefox browser. The first one allows to communicate
with the server from a remote web page, the second one displays an interface
either in a local computer or through the net, with the same browser.
The main difference is in the use of Canvas (HTML tag) to extend Ajax and to extend XUL, XPCom and XBL.
Some current developments will reinforce again the importance of Ajax by providing standard for RIA (Rich Internet Applications), mainly HTML 5 that extends HTML with Web applications features and that allows a Web application to run offline.
- Ajax Tutorial. Learn Ajax and XMLHttpRequest.
- Ajax API library. Google centralizes the loading of a framework among a selection of the most popular and will keep them indefinitely available online.