Structure-driven crawler generation by example

Many Web IR and Digital Library applications require a crawling process to collect pages with the ultimate goal of taking advantage of useful information available on Web sites. For some of these applications the criteria to determine when a page is to be present in a collection are related to the page content. However, there are situations in which the inner structure of the pages provides a better criteria to guide the crawling process than their content. In this paper, we present a structure-driven approach for generating Web crawlers that requires a minimum effort from users. The idea is to take as input a sample page and an entry point to a Web site and generate a structure-driven crawler based on navigation patterns, sequences of patterns for the links a crawler has to follow to reach the pages structurally similar to the sample page. In the experiments we have carried out, structure-driven crawlers generated by our new approach were able to collect all pages that match the samples given, including those pages added after their generation.