Abstract

World Wide Web (Web) documents, once delivered in a form that remained constant whilst viewed, are now often dynamic, with sections of a page able to change independently (and not requiring a full page reload), either automatically or as a result of user interaction. In order to make these updates, and hence their host pages, accessible, it is necessary to detect when the update occurs and how it has changed the page, before determining how, when and what to present to the user. This can only be achieved with an understanding of the technologies used to achieve dynamic updates and the human factors influencing how people use them. This report classifies the types of update that may be included on a page and reviews the techniques available to Web developers for achieving them. This is complemented by an analysis of Web pages, including the most popular pages and a random selection, which investigates how frequently some technologies are implemented. While JavaScript is used in nearly all sites, and Flash in about half, AJAX is used in some 20% of the current top 20 pages.