| It seams that every web programming book written today has the word Ajax in the title. What is Ajax? It is an acronym initiated by Jesse James Garrett of Adaptive Path, LLC. It stands for Asynchronous JavaScript and XML. Ajax is a new way of using some things that have been around for some time now; XHTML, CSS, DOM, JavaScript and XMLHTTP (originally an ActiveX object). All these things together becomes Ajax; the next generation of interactive website programming. When the web first became popular, we had static webpages which contained hyperlinks leading to other static webpages. Then can JavaScript, the DOM and DHTML which added the beginnings of interactivity to the web. But up to that point, there were only two major players. On the one side you had the client, which is the web browser and the reader's computer OS. On the other side you had the server, which has been the backbone of the web. In the past, the web browser would request a webpage from the server and the server would send that page to the reader's computer. This works fine but is a bit slow for today's busy web surfer. Every time a request is made to the server, the reader is forced to sit and wait at the computer screen until the webpage appears. A shopping cart program is a good example. When you click on the button to add an item to your shopping cart, this information is sent to the server where it is processed. In reply, the server sends a new page with a confirmation back to the browser. This is the traditional client-side/server-side communication and it requires the reloading of a webpage for each task performed by the server. However, the new XMLHTTP (XMLHttpRequest class) is starting to change this. Ajax is one of the better ways to use XMLHTTP. Examples of Ajax in action are Google Maps TM and Google SuggestTM. As you type your search term into the Google Suggest search engine, you will notice a drop-down list of suggested search terms that updates as you continue to type. By using this new technology, this list is continuously updated without the wait needed to reload your webpage. The benefit of programming with Ajax is new, more responsive web applications for your website. |
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