Foundations of Atlas

T he last year has seen a series of incredible advances in user experiences on the Web. As the Web continues to grow as a marketplace for web applications and services, the user expe- ence has become a key differentiator in attracting and retaining users and in driving revenue and productivity. This has led to an explosion of richer, more personalized, more interactive sites that fully exploit the capabilities of the browser platform. What is all the more remarkable about this trend is that it is built on a technology fo- dation that has been around for a long time and has only recently acquired the name Ajax. Microsoft pioneered both Dynamic HTML and CSS in Internet Explorer nearly a decade ago, and the current edition of the JavaScript language is several years old. And the cornerstone of Ajax-the XMLHttpRequest object, which enables more flexible communication between the browser and server-was built into Internet Explorer in 1998 to support pioneering appli- tions such as Outlook Web Access. So why has Ajax suddenly started to catch on now? Clearly, the technology has matured and standardized; Ajax's capabilities are available on more platforms and browsers than ever before and can now be found on the vast majority of desktop computers. The computing power of the desktop computer has also grown significantly. And, finally, the Web itself has evolved into a rich platform. These trends have, in turn, driven the need to invest in better, more differentiated experiences.