Crawling the Hidden Web

Current-day crawlers retrieve content only from the publicly indexable Web, i.e., the set of web pages reachable purely by following hypertext links, ignoring search forms and pages that require authorization or prior regis-tration. In particular, they ignore the tremendous amount of high quality content “hidden ” behind search forms, in large searchable electronic databases. In this paper, we provide a framework for addressing the problem of extracting content from this hidden Web. At Stanford, we have built a task-specific hidden Web crawler called the Hidden Web Exposer (HiWE). We describe the architecture of HiWE and present a number of novel tech-niques that went into its design and implementation. We also present results from experiments we conducted to test and validate our techniques