Ajax has become a huge buzzword over the past two years, and it is often mentioned in the same breath as another buzzword — Web 2.0. Neither term refers to something concrete or downloadable, but they’ve both been coined to reflect the changing face of the Web. Web 2.0 is as much about an attitude and a mindset as it is about new developments. Several innovations have emerged concurrently to create this sea of change, such as wikis,blogs, newsfeeds, third-party application programming interfaces (APIs), and web services. Ajax is one of the prime enablers. Ajax is not a technology in itself, but rather an umbrella term used to describe how several existing technologies such as JavaScript, the Document Object Model (DOM), and Extensible Markup Language (XML) can be used together to create Web applications that are more interactive and that remove the
need for entire web pages to be refreshed when only part of the page is changing.While the term “Ajax” appeared only fairly recently, the technologies used in Ajax applications have been around for several years, and some programmers have been using Ajax-style technologies and techniques for half a decade at least. In the past year, though, there has been a rapid increase in the number of Web sites that are using Ajax-style techniques. Furthermore, a lot of new job positions are requiring that programmers
know how to program Ajax-style applications. This book helps programmers to understand the core technologies behind the term “Ajax” and to start building sites using Ajax techniques. While many people have heard of Ajax, few understand how to write applications using these techniques. Ajax blurs the traditional boundaries between front-end developers and server-side developers, and it forces a new evaluation of the way applications should be created, as well as the kind of prerequisites a user interface should offer.
Ajax doesn’t require new software, new servers, or tools. It’s about making use of what is already available. It’s about challenging perceptions that everything is necessarily done on the server. It’s about going back to old ideas and breathing new life into them. It’s about fundamentally changing the way in which the Web works.