document: Not so creepy crawler : easy crawler generation with standard xml queries Web crawlers are increasingly used for focused tasks such as the extraction of data from Wikipedia or the analysis of social networks like last . fm . In these cases , pages are far more uniformly structured than in the general Web and thus crawlers can use the structure of Web pages for more precise data extraction and more expressive analysis . In this demonstration , we present a focused , structure-based crawler generator , the `` Not so Creepy Crawler '' ( nc2 ) . What sets nc2 apart , is that all analysis and decision tasks of the crawling process are delegated to an ( arbitrary ) XML query engine such as XQuery or Xcerpt . Customizing crawlers just means writing ( declarative ) XML queries that can access the currently crawled document as well as the metadata of the crawl process . We identify four types of queries that together sufice to realize a wide variety of focused crawlers . We demonstrate nc2 with two applications : The first extracts data about cities from Wikipedia with a customizable set of attributes for selecting and reporting these cities . It illustrates the power of nc2 where data extraction from Wiki-style , fairly homogeneous knowledge sites is required . In contrast , the second use case demonstrates how easy nc2 makes even complex analysis tasks on social networking sites , here exemplified by last . fm .
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