Ajax is a growing new technology at the time of this writing and we’re delighted to bring you the lowdown on it, in the inimitable style of Manning’s In Action series. In doing so, though, we faced an interesting problem. Although Ajax is indisputably hot, it isn’t really new. It isn’t really a technology, either.

Let us explain. Ajax brings together several well-established web technologies and uses them in new and interesting ways. Learning to use a completely new technology for the first time is in some ways simpler because you start with a blank slate. Ajax is different: there is also much to unlearn. Because of this, our book is organized somewhat differently from most Manning In Action books. You may notice this when reading and should know that we feel the way it is organized best suits this subject.

And, as you will see, although the Ajax technologies themselves are all client side, the differences extend all the way down to the server. This book is mainly about client-side programming, and most of the code examples that you’ll find in here are JavaScript. The principles of Ajax decouple the client from the server beautifully, and can be used with any server-side language. We’ve therefore got a broad audience to address and have opted to present our server-side code in a mixture of languages: PHP, Java, C#, and Visual Basic .NET. More importantly, though, we’ve tried to keep the server-side code relatively simple and implementation-agnostic, so that you can port it to what-ever environment you choose. Where we do use language-specific features, we explain them in enough detail for those unfamiliar with that particular environment to figure out what we’re doing.