More Related Content


Mining a Large Web Corpus

  1. Slide 1 International Internet Preservation Consortium General Assembly 2014, Paris Mining a Large Web Corpus Robert Meusel Christian Bizer
  2. Slide 2 The Common Crawl
  3. Slide 3 Hyperlink Graphs Knowledge about the structure of the Web can be used to improve crawling strategies, to help SEO experts or to understand social phenomena.
  4. Slide 4 HTML-embedded Data on the Web Several million websites semantically markup the content of their HTML pages. Markup Syntaxes  Microformats  RDFa  Microdata Data snippets within info boxes
  5. Slide 5 Relational HTML Tables HTML Tables over semi-structured data which can be used to build up or extend knowledge bases as DBPedia. • Cafarella, et al.: WebTables: Exploring the Power of Tables on the Web. VLDB 2008.  In a corpus of 14B raw tables, 154M are „good“ relations (1.1%)
  6. Slide 6 The Web Data Commons Project  Has developed an Amazon-based framework for extracting data from large web crawls  Capable to run on any cloud infrastructure  Has applied this framework to the Common Crawl data  Adaptable to other crawls  Results and framework are publicly available  Goal: Offer an easy-to-use, cost efficient, distributed extraction framework for large web crawls, as well as datasets extracted out of the crawls.
  7. Slide 7 Extraction Framework AWS EC2 Instance AWS EC2 Instance Master AWS SQS AWS EC2 Instance AWS S3 1: Fill queue 2: Launch instances 3: Request file-reference 4: Download file 5: Extract & Upload automated manual 6: Collect results
  8. Slide 8 Extraction Worker AWS S3 AWS S3 WDC Extractor .(w)arc Worker Filter output Worker: • Written in Java • Process one page at once • Independent from other files and workers Download file Upload output file Filter: • Reduce Runtime • Mime-Type filter • Regex detection of content or meta- information Worker
  9. Slide 9 Web Data Commons – Extraction Framework  Written in Java  Mainly tailored for Amazon Web Services  Fault tolerant and cheap  300 USD to extract 17 billion RDF statements from 44 TB  Easy customizable  Only worker has to be adapted  Worker is a single process method processing one file each time  Scaling is automated by the framework  Access Open Source Code:  Alternative: Hadoop Version, which can run on any Hadoop cluster without Amazon Web Services.
  10. Slide 10 Extracted Datasets  Hyperlink Graph  HTML-embedded Data  Relational HTML Tables Hyperlink Graph HTML-embedded Data Relational HTML Tables
  11. Slide 11 Hyperlink Graph  Extracted from the Common Crawl 2012 Dataset  Over 3.5 billion pages connected by over 128 billion links  Graph files: 386 GB
  12. Slide 12 Hyperlink Graph  Degrees do not follow a power-law  Detection of Spam pages  Further insights:  WWW‘14: Graph Structure in the Web – Revisited (Meusel et al.)  WebSci‘14: The Graph Structure of the Web aggregated by Pay-Level Domain (Lehmberg et al.) Discovery of evolutions in the global structure of the World Wide Web.
  13. Slide 13 Hyperlink Graph Discovery of important and interesting sites using different popularity rankings or website categorization libraries Websites connected by at least ½ Million Links
  14. Slide 14 HTML-embedded Data More and more Websites semantically markup the content of their HTML pages. Markup Syntaxes RDFa Microformats Microdata
  15. Slide 15 Websites containing Structured Data (2013) 1.8 million websites (PLDs) out of 12.8 million provide Microformat, Microdata or RDFa data (13.9%) 585 million of the 2.2 billion pages contain Microformat, Microdata or RDFa data (26.3%). Web Data Commons - Microformat, Microdata, RDFa Corpus  17 billion RDF triples from Common Crawl 2013  Next release will be in winter 2014
  16. Slide 16 Top Classes Microdata (2013) • schema = • dv = Google‘s Rich Snippet Vocabulary
  17. Slide 17 HTML Tables • Cafarella, et al.: WebTables: Exploring the Power of Tables on the Web. VLDB 2008. • Crestan, Pantel: Web-Scale Table Census and Classification. WSDM 2011. In corpus of 14B raw tables, 154M are “good” relations (1.1%). Cafarella (2008) Classification Precision: 70-80%
  18. Slide 18 WDC - Web Tables Corpus  Large corpus of relational Web tables for public download  Extracted from Common Crawl 2012 (3.3 billion pages)  147 million relational tables  selected out of 11.2 B raw tables (1.3%)  download includes the HTML pages of the tables (1TB zipped)  Table Statistics  Heterogeneity: Very high. Min Max Average Median Attributes 2 2,368 3.49 3 Data Rows 1 70,068 12.41 6
  19. Slide 19  Attribute Statistics 28,000,000 different attribute labels WDC - Web Tables Corpus Attribute #Tables name 4,600,000 price 3,700,000 date 2,700,000 artist 2,100,000 location 1,200,000 year 1,000,000 manufacturer 375,000 counrty 340,000 isbn 99,000 area 95,000 population 86,000  Subject Attribute Values 1.74 billion rows 253,000,000 different subject labels Value #Rows usa 135,000 germany 91,000 greece 42,000 new york 59,000 london 37,000 athens 11,000 david beckham 3,000 ronaldinho 1,200 oliver kahn 710 twist shout 2,000 yellow submarine 1,400
  20. Slide 20 Conclusion Three factors are necessary to work with web-scale data:  Thanks to Common Crawl, this data is available  Like Amazon or other on-demand cloud-services  The Web Data Commons Framework, or standard tools like Pig  Cost evaluation on task-base, but the WDC framework has turned out to be cheaper Availability of Crawls Availability of cheap, easy-to-use infrastructures Easy to adopt scalable extraction frameworks
  21. Slide 21 Questions  Please visit our website:  Data and Framework are available as free download  Web Data Commons is supported by: