Ajax can bring many advantages to an existing web application without forcing you to redo the whole thing. This book explains how you can add Ajax to enhance, rather than replace, the way your application works. For instance, if you have a traditional web application based on submitting a form to update a table, you can enhance it by adding the capability to update the table with changes to the form fields, without actually having to submit the form. That's just one example.
Adding Ajax is for those of you more interested in extending existing applications than in creating Rich Internet Applications (RIA). You already know the "business-side" of applications-web forms, server-side driven pages, and static content-and now you want to make your web pages livelier, more fun, and much more interactive. This
You don't need to start over to use Ajax. You can simply add to what you already have. This book explains how.
Too much use of libraries and references to Googling things... yes, I'm sure that's the way most people add Ajax but I expected more of the nitty gritty and maybe a chapter on external tools. Lots of useful approaches to ensuring that Ajax pages remain accessible and some good thoughts on security that saved me from giving the book a lower rating. I'd look at this book as providing inspiration more than instruction.