AJAX: Developing Interactive Web Content

Traditional internet programming consisted of forms that were used to capture user information. The users entered relevant information in forms and then submitted them to the server for processing. This method of form submission and server response methodology was highly effective through the years. However, with the increased penetration of internet, better browser capabilities and wide availability of broadband connectivity, the power of the browser is shifting from a simple form based user processing to real-time, dynamic user interactivity. Enter the world of AJAXWhat is AJAX? AJAX is an acronym for Asynchronous Javascript and XML. Although AJAX sounds like a new technology that has to be adopted for mass penetration, it is far from that. AJAX is nothing but a methodology of application development for the web using existing technologies like JavaScript, XML and Server side processing. AJAX uses the full functionality offered by web browsers to create highly interactive application on the web. What Does AJAX Do? AJAX uses available technologies to create dynamic sites.

1. Site using AJAX communicate with the server without having to reload the page
2. AJAX uses XML data to send data between the client and the server to update the pages with the latest information.
3. AJAX uses existing technologies such as DHTML, Javascript, XML and server side technologies like PHP, Java Servlets and ASP.

With such capabilities, the web browser can be converted into a near-windows console based application interface with the benefit of universal availability. The Architecture of AJAX At the heart of AJAX is the XMLHttpRequest object. The XMLHttpRequest object comes as part of an ActiveX Control library available from Microsoft Internet Explorer 5.0. The XMLHttpRequest object helps to communicate with the server at the back-end while the page is completely loaded. The server processes the information and sends back a response that is recieved by the browser and then processed to be displayed on the screen. The advantage is that, AJAX helps to convert a Non-persistent communication protocol like HTTP into a seamless interface for the user. The XMLHttpRequest object is present in most web browsers. The Use of AJAX has not been popular till recently due to the lowered bandwidth, lack of compatibility between browsers and the complexity of developing application using several different technologies. With the growth of AJAX usage like Google’s Gmail and several Web 2.0 applications, the functionality and cost of development of such applications has gradually come down to affordable levels. AJAX uses the comprehensive functionality of Javascript and Dynamic HTML to render interactive web pages. The beauty of AJAX is in the drastic reduction in the communication bandwidth of application by sending only relevant data to and from the server instead of reloading the pages for every user interaction. This provides great savings in terms of loading on the server as well as implementing the user interface logic on the client-side. The following technologies need to be used for the development of AJAX.

1. DHTML & Javascript - The DHTML and Javascript technologies are used for the client side processing of information obtained from the server. The Logic is in the form of javascript code that resides on the client browser and communicates with the server. The response from the server is then processed and then updated to the web-page from within the client interface.
2. CSS - The CSS provides a level of seperation from the logic and presentation. The CSS is used to provide a comprehensive source of presentation and rendering information to the browser to display the contents in a professional format.
3. XML - The XML is the fundamental back-bone of AJAX. Communication between the client and the server is done through packaging information in XML format and sending them to the server through an XMLHttpRequest. The response obtained from the server would also be in XML format which the JavasScript uses to process and present the information.
4. Server-Side Scripting- The server side scripting is any standard server side processing technology like PHP, Java Servlets and ASP. The speciality of the server side processing is the transmission of data as XML messages.

The designing and development of AJAX application requries comprehensive planning due to the different technologies that need to interact with each other. It is something of a choreography of an orchestra for the best performance. Application of AJAX AJAX is a new technology that is showing thriving growth in the area of interactive web application development. Some of the potential application areas are as follows

1. Online ERP applications
2. Login and User Registration
3. Web-Based mail applications
4. Service based application offerings
5. Interfaces requiring complex user interactivity

The advantage of using AJAX for your web application development is that part of the complexity of the business logic resides on the client browser, eliminating the loading conditions on your server with repeated client to server communication. However, the business logic still resides in Javascript and HTML pages, thus making upgrading and maintenance a simple process. One does not need to go from PC to PC to upgrade software or create batch file updates. Upgrading business logic is simply dome on the web pages and those logic are downloaded as Javascript, CSS and DHTML files onto the client browser. Conclusion AJAX defines the next generation of internet technologies that is more or less termed as “Web 2.0″. They provide a whole new meaning to the term Web interactivity. Using existing technologies, AJAX can be immediately used to develop rich applications and deployed without any effort. Source: SKYBLOG