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because we’ve found them to be invaluable, practical tools in working with Ajax. And we think you will too as you start to pick up speed. In chapters 4 and 5, we turn our sights on the core components of Ajax, and apply our design pattern knowledge to find the best practices. Chapter 4 looks at ways of keeping your code clean on the client itself, applying the old web workhorse, Model-View-Controller, in a new way. Chapter 5 looks at the different ways of communicating between the client and the server and how various types of frameworks can be adapted to work with Ajax. By this point, we have covered all the basic plumbing and you’ll know how Ajax operates end to end.

Chapters 6 through 8 build on the fundamental knowledge that we’ve acquired to look at how to add polish to your application and go beyond a proof of concept to something that’s fun, and safe, to usable in the real world. Chapter 6 addresses the user experience, and takes an in-depth look at ways of keeping the user informed while asynchronous tasks are executing. There’s a balance to be struck between keeping out of the user’s way and keeping him in the dark, and we show you how to find that happy middle ground here.

Chapter 7 looks at the issue of security in Ajax from a number of angles. Ajax is a web technology and many of the issues that it faces are no different from any other web app. We cover the basic ground, concentrating on Ajax-specific issues here, such as securely importing generated JavaScript from the server, and protecting your web service entry points from unwanted direct manipulation. Security can be a showstopper for serious applications, and we give the basic steps needed to keep it under control here.

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ABOUT THIS BOOK

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Chapter 8 discusses that other showstopper, performance (or rather, lack of it!). We show how to monitor the performance of your application and how to analyze code in order to improve it and keep those improvements consistent across an application.

In part 4, which consists of chapters 9 through 13, we switch gears to look at a number of Ajax projects. In each case, we code the functionality up in a straightforward way and then refactor it into something robust that you can drop into your own projects with no more than a few lines of code. This gives you the benefit of understanding the principles, the benefits of reuse, as well as showing Ajax refactoring in action.

In chapter 9, we look at a simple way to give the user a richer experience by enhancing HTML forms with Ajax: we use data entered in one field to prepopulate a second drop-down list by making a background request to the server. We continue the theme of form enhancement in chapter 10 with an implementation of type-ahead suggest, fetching data from the server in response to user keystrokes.

Chapter 11 moves on to the wider possibilities of Ajax user interfaces. We develop a complete portal application that resembles a workstation desktop more than a web page, complete with its own draggable, resizable windows. Ajax processes track window movements in the background, so that the desktop is always in the same state you left it, even if you log back in on a different machine. Chapter 12 develops an Ajax-based search system and demonstrates the power of client-side XSLT as a way of turning raw XML data into formatted, styled content.

In chapter 13, we present an Ajax client without a back-end implementation. It still talks to server processes, but in this case, does so directly to blog and news syndication feeds, using the Internet standard RSS protocol.

Finally, we include three appendices that we hope you’ll find useful. The body of the book discusses the technology itself. With a new, cross-disciplinary technology, assembling the tools to use it effectively is more of a challenge than with a mature technology stack such as J2EE or .NET. The vendors haven’t started offering Ajax tools yet, but we’re sure that they will! In the meantime, we provide in appendix A an overview of the tools and tricks