Peter Parkar asked:


It’s often a difficult scenario on the part of an I.T aspirant to get into a thorough analysis of the particular subject matter but since the advent of internet as a valuable source of information, there have been the emergence of tutorials that are available online related to Ajax. The first and foremost tutorial defines AJAX that stands for Asynchronous JavaScript and XML. It is the use of the nonstandard XMLHttpRequest object to communicate with server-side scripts. It can send as well as receive information in a variety of formats, including XML, HTML, and even text files. The tutorial provides with Ajax’s most appealing characteristic, of having an “asynchronous” nature, which means it can do all of this without having to refresh the page.

The Ajax tutorial gives an introduction to ECMAScript for XML (E4X), a simple extension to JavaScript that makes XML scripting very simple. The tutorial has related information on how to make asynchronous requests with JavaScript and Ajax, informative material on Ajax – Try/Catch Blocks of Code, sending requests with XMLHttpRequest to allow user to make requests and receive responses, adding AJAX to a website, Form validation with AJAX/PHP/MySQL, Callbacks and Ajax where user sets the onreadystatechange property of the XMLHttpRequest object to the name of the function to run. Then, when the server has processed the request, it will automatically call that function, to build Ajax-enabled applications using Dojo and JSON, the two very different but complementary technologies that can significantly enhance the interface and usability of web applications and more reference tutorials.

There are mini-tutorials on the black art of iframes and browser history, known to AJAX experts but rarely presented clearly, mini-tutorial on saving state across page loads on the client side, without using cookies so as to save large amounts of data beyond cookies size limits, valuable and effective resource on Easy Ajax with jQuery, Top Ajax Poller Scripts, fast introduction to the basics of Ajax for people that already know how to write the server-side part of the process using servlets and JSP, AJAX username availability checking that allows a user who is registering for your site to see if the username they want to use is taken already or not, without having to submit a form and reload the page, RadAjaxPanel that exposes a rich set of client-side events which allow for easy and flexible use in a wide range of application scenarios and tutorial that explains on how to work with the XML Response or “The X-Files” and more in line in order to enhance and learn new aspects in AJAX. Online education therefore is the most reliable and active source for gaining knowledge for I.T. aspirants through, ASP, Java and AJAX tutorial and the internet is a vast knowledge based environment making things a little more easy with downloadable and accessible information relevant to AJAX.

Susen G asked:


JavaScript is client side scripting language. When you open a web page your web browser first downloads all the necessary files from the server to display that page correctly. Those necessary files are HTML, CSS, Images, Videos, etc and the JavaScript files too. After completing download the browser displays that page on its window and any script linked with it will run from the downloaded script file.

In Ajax technology, user inputs and other data are sent to the web server through JavaScript. JavaScript creates XML_HTTP_REQUEST_OBJECT to connect with the server, submit data to it, and to request a response from the server. When response comes, a JavaScript event fires and the function associated with that event is then executed. So in Ajax technology JavaScript is only used to transfer data between client side and the server side while the main program, i.e. data processing is executed at the server end, in PHP or any other server side language.

As JavaScript runs from the client computer its execution time is very short, almost instantaneous. Viewers can run JavaScript without being connected with the server as well. But in Ajax, viewers must be connected to the server. Here execution time is much longer which depends on their Internet connection speed, server hardware and number of bytes to be transferred between client side and server side.

In terms of server security JavaScript is absolutely safe since it doesn’t transfer any user input from client side to the server. But in Ajax you have to take special care to prevent any malicious data from the bad users.

In JavaScript you can’t hide your source code. Users can easily read your source code from source view which is running on their computer. But in Ajax data processing takes place at the server end and so user can’t see the program source code.

In Ajax you can support your program with your server database.

For a long program, if you use JavaScript to implement it, the size of your web page will be larger. So it will take longer time to download which is a bad SEO feature. But in Ajax you can run long program, processing several thousands of data from a database, still your page size keeps small.

Since all browsers do not strictly follow any particular standard so it is not very easy to write a browser independent JavaScript program.

JavaScript are only used in some specific applications where data security is not an important consideration while the scope of Ajax technology application is unlimited.

Rakhee Chowdhary asked:


AJAX has not only sprouted but has got root hold in developing dynamic web applications, that reflects changes in micro seconds thereby saving reloading time, improving usability, providing faster accessibility, to more web pages in lesser time. AJAX, acronym for Asynchronous Javascript And XML is the term whispered from almost every software developer mind and its waves are touching the network boundaries.

Ajax Applications Development has provided breakthrough in web application development. AJAX is a new way to define technology shifting web pages from HTML static pages to advance Java script and CSS enabled dynamic pages. AJAX is also called a free framework for fast creation of interactive cross-platform web experiences. This application has transformed the look, feel of web and has solved the major problem of web application of reloading.

Conglomeration of many technologies to form a more useful, dynamic, stronger technology – AJAX has accelerated the web world. Ajax incorporates standards-based presentation using XHTML and CSS; dynamic display and interaction using Document Object Model; data interaction and manipulation using XML; asynchronous data retrieval using XMLHttpRequest and Java Script binding together everything. AJAX uses Java script technology, HTML pages make asynchronous call to the server from which it fetches information that may be formatted as HTML, plain text, XML or Java Script Object Notation (JSON). To modify the Document Object Model (DOM) of the HTML page java script uses this content. Load of content on demand for various complex web applications has improved bandwidth usage by cutting down bandwidth consumption for complex functionalities.

AJAX is based on different server side architecture to support interaction model. Intermediate application layer, an Ajax engine (written in java script), is added in between user and server that allows asynchronous user’s interaction with application. This new approach has many benefits over static web applications, main features of AJAX include: Real-time form validation with server-side validation of codes. Auto-completion of form fields, better interaction and control with the use of advanced controls available. Content mix from third party application with your application is easily possible. Google Maps, Flickr, Orkut, Google Suggest are examples of AJAX application development.

Inspite of its myriad benefits, ajax application development is facing few major challenges: in-depth knowledge is required to understand upgrading Ajax functionality as it is not easy to develop Ajax that involves running complex java script code on client. Another challenge is that XMLHttpRequest object is not part of Java script technology specification, so it makes adaptablity difficult for older browsers. Even though browser add-ons have made debugging easy, processing logic embedded in client and on server makes application debugging difficult. Easy data access have provided easy way to plagiarism, except for restricted sections. Identifying particular state of application is difficult, this creates problem for user to bookmark specific application state. Also, iframe element used to populate browser history is not recommended by W3C. Websites using Ajax applications are generally not search engine friendly. Ajax has java script code that has compatibility problems with different browsers. Web analytics tracked records get cluttered with websites using Ajax technology as every event is tracked by analytics.

Careful consideration is required before implementing Ajax technology for your website to overcome few of its fallback.