Written by: Wallace B. McClure, Scott Cate, Paul Glavich, Craig Shoemaker
Pages: 362
Publisher: Wrox
ISBN: 047178544X

Introduction

From an Ajax book written for beginners, I expect two things: the first one is a lot of information and reference about the technologies used when developing Ajax applications (thus not only the XmlHttpRequest object, but also JavaScript, the DOM, CSS, XML, XSLT, JSON and the many others). The second one is making the developer understand that powerful Ajax-enabled web applications are built on the top of a framework, and guiding him through the frameworks jungle to make the right choice based on requirements and goals. The two logical parts that make up this book address these two requirements.

Book structure

The book is made up of 362 pages divided in 13 chapters, plus an Appendix dedicated to the XSLT commands. It is logically divided in two parts: the first parts deals with the concepts and technologies that a developers who is going to enter the AJAX world must know in order to be able to develop a modern web application. As we know, these set of technologies and techniques are quite large, starting from JavaScript and the DOM, arriving to the glorious XmlHttpRequest object, at the roots of every Ajax -enabled web application. The second part aims to offer a detailed overview of the main Ajax frameworks available. Since developing web applications can be quite difficult due to browser incompatibilities and different implementations, choosing a robust framework upon which to build it, is a winning approach.

DHTML and AJAX explained

Chapters from 1 to 5 make up the first part of the book. After introducing Ajax and talking about its main goal (improving the user experience) and some development scenarios, the reader is introduced to DTHML and the large set of web technologies that it encapsulates. This part of the book is rich in terms of background information, concepts and sample code. One of the main chapters is dedicated to JavaScript and the DOM and I consider it a very good introduction to the topic. The first part ends with a whole chapter dedicated to the glorious XmlHttpRequest object, which provides the infrastructure needed to send the asynchronous web requests upon which every Ajax web application relies. The chapter on the XmlHttpRequest object is very exhaustive, with lot of references and code snippets. I particularly enjoyed the chapter about data communication; this chapter introduces two of the most used data formats, XML and JSON, and languages for accessing and displaying data like XPath and XSLT.

Choosing the right framework

Starting from chapter 6, a deep examination of the Ajax frameworks available is done. Since it occupies more than a half of the book, this part implicitly demonstrates the necessity to build an Ajax -based web application on the top of a framework. Frameworks do the dirty job of handling cross-browser incompatibilities, dealing with the different XmlHttp object implementations, providing a common and consistent infrastructure, therefore choosing one of them is the recommended approach. But which one? The authors did a good job of exploring almost all the most popular Ajax frameworks around: they analyzed, played and wrote code for 9 different frameworks. The journey starts from ASP.NET and its callback mechanism, not the best framework available but useful in some control development scenarios and used in server control like the TreeView and the GridView. Two chapters are dedicated to Ajax.NET Professional, with an interesting section that looks under the hoods of this library.

The last three chapters of the book are dedicated to “Atlas” (now Microsoft ASP.NET Ajax), the Microsoft’s Ajax framework that extends ASP.NET with client-side capabilities. The framework is explored in great detail and I can say that is one of the most complete and accurate documentation sources available. The only drawback is that this material is going to become a little outdated due to the recent changes announced for the first official release of MS Ajax, thus be sure to check the Wrox website for the latest book updates and to download the code for all the examples.

The very last chapter deals with debugging. A whole chapter dedicated to debugging is great. I must mention this chapter because it helps the developer to setup the environment in order to debug JavaScript code in Visual Studio, and using Internet Explorer or Firefox with tools like Fiddler or Venkman.

Conclusions

The book is full of concepts and sample code. There are many illustrations and tables that provide a useful reference to the developer. Almost each subsection contains a little snippet that demonstrates what previously said and at the end of each chapter the authors provide links to net resources. While this book is a “beginning” one, I must say that I often find there the answers that I need. On the other hand, while I have appreciated the tons of examples and things like the little framework built on the top of the XmlHttpRequest object, I think the book needs more pieces of re-usable code, i.e. some controls or components that the user can embed in his personal library and start improving them. Four stars out of five.

• Lots of sample code
• Lots of useful illustrations and tables
• Many and clear code examples

• Many examples but not much reusable code
• The “Atlas” part is going to be outdated

About Alessandro Gallo

Alessandro "Garbin" Gallo is a Microsoft MVP in the Visual ASP/ASP.NET category and a .NET developer/consultant. He is a contributor for the Ajax Control Toolkit project, owned by Microsoft. Alessandro won the Grand Prize at the "Mash-it-up with ASP.NET AJAX" contest held by Micr... This author has published 23 articles on DotNetSlackers. View other articles or the complete profile here.