Ajax Q&A

The Original FAQ by Jesse James Garrett

French translation of Denis Sureau's Q&A section on 26 October 2006.

March 13, 2005: Since we published Jesse's essay, we have received a huge amount of correspondence from readers with questions about Ajax. In this Q&A, Jesse answers some of the most frequently asked questions.

Question. Did Adaptive Path invent Ajax? Did Google? Adaptive Path helps Google build Ajax apps?

A. Neither Adaptive Path nor Google invented Ajax. Google's latest products are just examples of Ajax apps that are the most prominent. Adaptive Path was not involved in the development of Google's Ajax apps, but we occasionally did Ajax work for some of our other customers.

Question. Does Adaptive Path sell Ajax components or trademark? Where can I download it?

The answer. Ajax is not something that can be downloaded. This is an approach, a way to think about the architecture of web applications that uses certain technologies. Neither the Ajax name nor the approach is the property of Adaptive Path.

Question. Is Ajax just another name for XMLHttpRequest?

A. No. XMLHttpRequest is only one part of the Ajax equation. XMLHttpRequest is a technical component that provides asynchronous communication with the server; Ajax is our name for the general approach described in the article, which relies not only on XMLHttpRequest, but also on CSS, DOM and other technologies.

Question. When did you experience? Do you need to give it a name?

The answer. When discussing this approach with clients, I needed to be able to use something shorter than "asynchronous JavaScript + CSS + DOM + XMLHttpRequest."

Question. The technique of asynchronous communication with the server has existed for several years. What makes Ajax a "new" approach?

The answer. What is new is the preferential use of these methods in real applications to change the fundamental model of interaction on the Internet. Ajax is taking over now because these technologies and the industry's understanding of how to deploy them have been slow to develop.

Question. Is Ajax a technology platform or is it an architectural style?

A. It's both. Ajax is a set of technologies used together in a particular way.

Question. Which Ajax apps are best for?

A. We don't know yet. Because this is a relatively new approach, what we know about the areas where Ajax is best applied is still in its infancy. Sometimes the traditional web application model is the most appropriate solution to the problem.

Question. Does this mean that Adaptive Path supports anti-Flash?

A. Not at all. Macromedia is a client of Adaptive Path, and we have long been supporters of Flash technology. As Ajax mature, we expect Ajax to be the best solution for a particular task, and sometimes the best solution will be the Flash. We are also interested in exploring ways to mix technologies (as is the case with Flickr, which uses both).

Question. Does Ajax have sufficient availability or browser compatibility limitations? Do Ajax applications disable the Back button? Is Ajax compatible with REST? Are there any safety concerns when developing Ajax? Can Ajax applications work with users who have JavaScript disabled?

The answer to all these questions is: ons is "maybe." Many developers have already worked on how to overcome these problems. We believe more work is needed to identify all Ajax limitations, and we expect the Ajax developer community to reveal more issues over time.

Question. Some Google examples you give don't use XML at all. Do I need to use XML and/or XSLT in Ajax?

A. No. XML is the most advanced way to get data from and from an Ajax client, but there's no reason why you can't achieve the same effects with a technology like JavaScript Object Notation or a similar way to structure the data to be exchanged. Making complex code efficient and error-free is not an easy task, and to solve this problem we will need more advanced development tools and frameworks.

Question. Do Ajax applications always deliver better results than traditional web applications?

A. Not necessarily. Ajax gives interaction developers more flexibility. However, the more power you have, the more caution you need to take when using it. We need to be careful Use Ajax to improve what happens to the user of our apps, not make it worse.

Jesse James Garrett is director of user experience strategy and founder of Adaptive Path.He is the author of the widely referenced book The Elements of User Experience.

Part One: A Brief Approach to Web Applications.