AJAX: A New Approach to Web Applications

AJAX seems to be the word of fashion in the "world" development of Web applications. But it should be
clear that in reality AJAX is not a technology, AJAX is a technique, is the union of several technologies, such as DOM, XML, XSLT, CSS, XMLHttpRequest, JavaScript, among others, to achieve truly amazing things, such as GoogleMaps , Gmail, Outlook Web Access among other Web applications.

Introduction

The designers of Web sites can not help feeling envious of our colleagues who create desktop software. Desktop applications have a richness and response that seemed out of reach on the Internet. Hence one of the objectives of introducing into our AJAX Web applications, is to simulate or closer to desktop applications.

History of AJAX

Although the term "AJAX" was created in 2005, the history of the technologies that enable AJAX goes back a decade earlier with the initiative in the development of Microsoft Remote Scripting. However, the techniques for asynchronous loading of content in an existing page from the introduction of the iframe element in Internet Explorer 3 in 1996 and the type of element layer in Netscape 4 in 1997, abandoned during the early stages of development of Mozilla. Both types of the element had src attribute that could take any external URL, and loading a page containing JavaScript that manipulates the page paternal can achieve effects similar to AJAX.

The Microsoft's Remote Scripting (or MSRS, introduced in 1998) proved a more elegant replacement for those techniques, with sending data through a Java applet that can communicate with the client using JavaScript. This technique worked in both browsers, Internet Explorer version 4 and Netscape Navigator version 4. Microsoft used it in Outlook Web Access supplied with the 2000 version of Microsoft Exchange Server. The community of Web developers, the first working through the newsgroup microsoft.public.scripting.remote and after using blogs, they developed a range of remote scripting techniques to achieve the s
ame results in different browsers. Early examples include the library JSR in 2000, the introduction to the art image / cookie in the same year and JavaScript on-demand technology (JavaScript on Demand) in 2002. In that year, a change from the community of users to Microsoft's Remote Scripting to replace the Java applet for XMLHttpRequest.

Remote scripting frameworks such as ARSCIF appeared in 2003 shortly before the introduction of Microsoft Callbacks in ASP.NET.

Since that XMLHttpRequest is implemented in most browsers, rarely used alternative techniques. However, we still are used where there is a need for greater compatibility, a small deployment, or access crossover between Web sites. An alternative, the SVG Terminal (based on SVG), employs a persistent connection to the ongoing exchange between the browser and the server.

AJAX Features

* The applications are more interactive, responding to user interactions faster, desktop-style applications.

* These applications have a look (look and feel) very similar to traditional desktop applications without relying on plugins or specific features of the browsers.

* It reduces the size of the exchanged information

Many micro-or petitions, but the overall data flow is lower

* To be released from processing to the server (to be performed on the client side)

* AJAX upgrade portions of the page instead of the full page.


Why AJAX is different?

An AJAX application eliminates these stops on the implementation by introducing an intermediary (the AJAX engine) between the user and the server. It would seem that adding a layer to the application it would confer a poorer response, but in fact the opposite is true.

Instead of loading a Web page, at logon, which makes the browser load the AJAX engine (written in JavaScript and usually tucked in a hidden frame).