AJAX Crawl: Making AJAX Applications Searchable

Current search engines such as Google and Yahoo! are prevalent for searching the Web. Search on dynamic client-side Web pages is, however, either inexistent or far from perfect, and not addressed by existing work, for example on Deep Web. This is a real impediment since AJAX and Rich Internet Applications are already very common in the Web. AJAX applications are composed of states which can be seen by the user, but not by the search engine, and changed by the user using client-side events. Current search engines either ignore AJAX applications or produce false negatives. The reason is that crawling client-side code is a difficult problem that cannot be solved naively by invoking user events. The challenges are: lack of caching, duplicate states detection, very granular events, reducing the number of AJAX calls and infinite event invocation. This paper sets the stage for this new search challenge and proposes a solution: it shows how an AJAX Web application can be crawled in the granularity of the application states. A model of AJAX Web sites is presented. An AJAX Crawler and optimizations for caching and duplicate elimination are defined, and finally, the gain in search result quality and corresponding performance price are evaluated on YouTube, a real AJAX application.