AJAX Extensions (code named Atlas, hence the book’s title) is Microsoft’s soon to be released AJAX solution. AJAX Extensions is a set of JavaScript extensions that provide partial page rendering, asynchronous callbacks and cross browser compatibility. The AJAX Extensions Control Toolkit is a library of AJAX controls that add a wide array of client-side functionality to AJAX enabled applications. All in all Microsoft’s AJAX Extensions is very impressive.

Programming Atlas by Christian Wenz is one of two books (at the time of this review) that covers this new technology and it covers it well. The author writes clearly and authoritatively and includes a wealth of background knowledge around the subject. The book is well laid out and flows well. I get the feeling that the book had to be rushed to print quickly (probably due to the need to get the information out before it became obsolete by subsequent betas and CTPs) as there are many typos throughout the book. Personally I find this forgivable because the book is well written and I would rather have the information now than without typos later. There are also a number of omissions from the book. There is no discussion of client-side exception handling, adding debugging support, logging or using alternative asynchronous postbacks routes such as the IFrameExecutor. I would also liked the section on Data Binding to have included information on creating AJAX Extension controls that support data binding (as opposed to binding to existing AJAX Extension controls). There is also no discussion on localization of AJAX Controls but this can’t be levelled as a criticism of the book because at the time of writing AJAX Extensions doesn’t have a localization model. The book also shows the nature of writing before the technology is released because the book can’t possibly be up to date with the most recent releases: the name Atlas has been replaced by AJAX Extensions, namespaces have changed and several controls have changed.

Don’t let these deficiencies put you off though. If you’re into AJAX Extensions then this is a well written and authorative book that is well worth having.