Ajax Patterns and Best Practices

Asynchronous Javascript and XML (Ajax) is a new technique that uses existing pervasive technology to build interactive web applications that mimic rich-client functionality. Ajax is unique because it combines technologies to make traditional web pages interactive. The advantage of using Ajax is the same as for the web, namely distribution capability, ease of deployment, and anywhere-anytime access.

Ajax Patterns and Best Practices enables you to just pick up the book and then write applications that work properly. This book is not just about the technical, low-level details of the API's, but is about making something happen on both the client and server. For example, the Ajax Widgets chapter outlines a number of canned widgets that perform some functionality. The book explains the widget implementation so you can not only understand what is happening, but copy and paste if necessary.

The book also covers the server side with the REST protocol. REST and Ajax dovetail elegantly with each other, but REST can also be used solo, with just a computer-to-computer solution. And like Ajax, REST can be used with today's existing technologies. Currently, millions of client computers are Ajax-ready, and mullions of servers are REST-ready.

The book is suitable if you’re a beginner, or if you have already created an Ajax application. Throughout the book, various patterns and best practices are outlined so that if you are more experienced, you can just glance and verify that you are building the most efficient Ajax application possible.

The Author

CHRISTIAN GROSS is a consultant/trainer/mentor with vast experience in the Internet paradigm. He has worked on software development and other solutions for many corporations, including Altova, Daimler-Benz, Microsoft, and NatWest. Gross has written multiple books, including Applied Software Engineering Using Apache Jakarta Commons, Open Source for Windows Administrators, A Programmer’s Introduction to Windows DNA, and Foundations of Object-Oriented Programming Using .NET 2.0 Patterns. He has been a regular speaker at many conferences, including Software Development, JAX, and BASTA, and has been track chair at many conferences as well.

Written for: Intermediate-Advanced Website developers and programmers


Leseprobe:

Chapter 1 Introduction to Ajax (p. 1-2)

Asynchronous JavaScript and XML (Ajax)1 is both something old and something new—old because already existing technologies are used, but new because it combines these existing technologies into techniques that very few considered previously. Simply put, because of Ajax a new generation of applications and ideas are bubbling on the developer scene. A very brief definition of Ajax is as follows: Ajax is a technology that complements Web 2.0 and the integration of many web services at once.

This brief definition poses more questions than it answers, as now you are likely wondering what Web 2.0 is and what the integration of many web services are. Web 2.0 can be thought of as the Internet economy.2 Think about something as typical as an encyclopedia, and you will start to think about salespeople who carry extremely heavy books and knock on doors. In a Web 2.0 context, an encyclopedia means Wikipedia (http:// www.wikipedia.org). The Wikipedia project is an open effort by humanity to record itself. Whereas for a traditional encyclopedia a set of writers and editors write about certain topics, Wikipedia is created by people who write about what they know. Get enough people together and you get an encyclopedia that is on the Internet. What is thought-provoking about the Wikipedia project is that anybody can edit it, and therefore it usually contains more current and unusual information than a traditional encyclopedia. In some instances Wikipedia’s selfcorrecting capabilities have proven to be problematic, but considering the scale and depth of the project, those instances have been exceptions.

The second part of Ajax is the integration of many web services at once. Ajax allows a higher level of interactivity in a HyperText Markup Language (HTML) page than was possible without Ajax technologies. The result is that an Ajax application changes from a web application to a web service manipulation technology. In a traditional web application, navigating content meant changing HTML pages. With Ajax, navigating content means navigating web services that could be generating HTML content, or Extensible Markup Language (XML) content, or other content.

Pictures Are Worth a Thousand Words

The definition explains Ajax, but you are probably still wondering what Ajax does. There is a saying that a picture is worth a thousand words, and the following images and their associated explanations illustrate best what Ajax does. Map.search.ch was one of the first major Ajax applications, and it illustrates the elegance of what an Ajax application can be. In a nutshell, Map.search.ch is used to find restaurants, houses, parking spots, and more throughout Switzerland. When you surf to the website http://map.search.ch, you will see something similar to Figure 1-1.