1. we.b : The web of short URLs Demetris Antoniades, lasonas Polakis, Gerogios Kontaxis, Elias Athansapoulos, Sotiris loannidis, Evangelos P.Markatos, Thomas Karagiannis FORTH-ICS, FORTH-ICS, FORTH-ICS, FORTH-ICS, FORTH-ICS, FORTH-ICS, Microsoft Research www 2011 March 30 2011 Presented by Somin Kim

2. Outline  Introduction  URL Shortening Services  Data Collection  The Web of Short URLs  Evolution and Lifetime  Publishers  Short URLs and Web Performance  Conclusion 2/36

3. Introduction  The idea behind URL shortening services is to assist in the easy sharing of URLs by providing a short equivalent one  Short URLs have seen a significant increase in their usage –Result of their extensive usage in Online Social Networks  Understanding the usage of short URLs is important –To provide insight into the interests of OSNs or IM systems –To know performance, scalability, and reliability of URL shortening services –To define the proper architecture for URL shortening services 3/36

4. Outline  Introduction  URL Shortening Services  Data Collection  The Web of Short URLs  Evolution and Lifetime  Publishers  Short URLs and Web Performance  Conclusion 4/36

5.  URL Shortening Services  Popularity of URL shortening services –The rapid adoption of OSNs has led to an increased demand for short URLs –Short URLs are also useful in traditional systems  such as IMs, SMSes, and e-mails URL Shortening Services(1/3) 5/36 Long URL http://www.this.is.a.lon g.url.com/indeed.html Long URL http://www.this.is.a.lon g.url.com/indeed.html Short URL http://bit.ly/dv82ka Short URL http://bit.ly/dv82ka access Redirected to original URL URL shortening Service bit.ly URL shortening Service bit.ly publish

6. URL Shortening Services(2/3)  Some of these services provide statistics about the accesses of these URLs –The number of hits –The referrer sites the hits came from –The visitor’s countries –…  Users can create many short URLs for the same long URL –If a user creates a short URL for the same long URL, the service will create a different hash that will be given to the user –For each unique long URL, bit.ly provides a unique global hash with an information page –Overall statistics will still be kept by the global URL’s information page 6/36

7. URL Shortening Services(3/3) 통계페이지 캡쳐해서보여 줄까 ? Global information 7/36

8. Outline  Introduction  URL Shortening Services  Data Collection –Collection methodology –Collected data  The Web of Short URLs  Evolution and Lifetime  Publishers  Short URLs and Web Performance  Conclusion 8/36

9. Data Collection(1/3) Collection Methodology  Twitter crawling –Twitter crawling returns links “gossiped” in a social network –We collected tweets that contain HTTP URLs –Only 13% of the HTTP URLs were not shortened by any URL shortening services –50% of the HTTP URLs from Twitter were from bit.ly URLs 9/36

10. Data Collection(2/3) Collection Methodology  Brute-Force –We can get hashes irrespective of their published medium and recency –We gathered metadata provided by the shortening service –We monitored the evolution of the keyspace in ow.ly system  Ow.ly serially iterates over the available short URL space  About 70000 new short URLs created each day 10/36

11. Data Collection(3/3) Collected Data  In case of twitter and bitly, all the accompanied metadata for each short URL are also collected 11/36

12. Outline  Introduction  URL Shortening Services  Data Collection  The Web of Short URLs –Where do short URLs come from? –Where do short URLs point to? –Location –Popularity  Evolution and Lifetime  Publishers  Short URLs and Web Performance  Conclusion 12/36

13. The Web of Short URLs(1/7) Where do short URLs come from?  Short URLs do not frequently appear in traditional web pages –The vast majority of users arrive at bit.ly from non-web applications –Users who access through web applications mostly come from social networking channels (Twitter, facebook) 13/36

14. The Web of Short URLs(2/7) Where do short URLs point to?  Most popular types of short URL contents –News and informative content come first –4% of the most accessed URLs in owly trace were shortening services  Spammers use short URLs packed inside other short URLs to avoid exposure of the long URL 14/36

15. The Web of Short URLs(3/7) Location  The penetration of short URL use is significantly different from that of the Internet/web –Most of these accesses come from the United States, Japan, and Great Britain –Any accesses from China and India was not seen  China and India are ranked in the top-5 countries with the largest number of Internet users 15/36

16. The Web of Short URLs(4/7) Popularity  URL popularity –Large systems that provide content to users typically exhibit the power-law behavior  A small fraction of the content is very popular  Most of it is considered uninteresting 16/36

17. The Web of Short URLs(5/7) Popularity  URL popularity (cont.) –We split short URLs into active and inactive  Inactive : no hit was observed during the last 7 days of trace –10% of the short URLs are responsible for about 90% of the total hits seen in trace 17/36

18. The Web of Short URLs(6/7) Popularity  Content popularity –Besides familiar websites, less known or popular websites were observed  Pollpigeon.com(short opinion polls), Mashable.com(social media news), Twibbon.com(Twitter campaign) –Short polls are popular contents  It’s very common in social networking sites 18/36

19. The Web of Short URLs(7/7) Popularity  Content popularity (cont.) –Do popular web sites significantly change over time?  About 6 sites appears every single day of April 2010 in the top-100 –22 sites for March 2010  About 400 sites enjoy short bursts of popularity 19/36

20. Outline  Introduction  URL Shortening Services  Data Collection  The Web of Short URLs  Evolution and Lifetime –Life span of short URLs –Temporal evolution  Publishers  Short URLs and Web Performance  Conclusion 20/36

21. Evolution and Lifetime(1/5) Life span of short URLs  Lifetime of a URL is the number of days between its last and first observed hit  Lifetime CDF of the traces (twitter2, bitly) –50% of the short URLs are not ephemeral –Inactive URLs have a shorter lifespan 21/36

22. Evolution and Lifetime(2/5) Temporal evolution  The daily change in the number of hits for each short URL –The number of accesses for a typical short URL varies by as much as 40% from one day to the next –As less popular URLs are included, larger daily changes are observed 22/36

23. Evolution and Lifetime(3/5) Temporal evolution –Inactive URLs  Average 60% of hits are observed during their first day  After that, hit rate drops sharply –Active URLs  First-day effect is also evident  A significant hit rate for recent days are also observed  The evolution of hit rate across the lifetime of the short URLs 23/36

24. Evolution and Lifetime(4/5) Temporal evolution  The daily hit rate with a short URL’s lifetime for inactive short URLs –There’s no obvious dependence of the daily hit rate with a short URL’s lifetime 24/36

25. Evolution and Lifetime(5/5) Temporal evolution  Total number of hits as a function of the short URL’s lifetime –Active short URLs(bottom) appear to exhibit a linear relationship in log-log scale 25/36

26. Outline  Introduction  URL Shortening Services  Data Collection  The Web of Short URLs  Evolution and Lifetime  Publishers  Short URLs and Web Performance  Conclusion 26/36

27. Publishers(1/4)  Twitter effect –Short URLs referred from Twitter enjoy significantly higher popularity 27/36

28. Publishers(2/4)  CCDF of posted short URLs per Twitter user –Most users published a handful of tweets with short URLs –The majority of tweets with short URLs are original Twitter messages (not retweets) 28/36

29. Publishers(3/4)  User’s daily publish rate of short URLs –Median rate is 1 short URL per day –98% or the user publish no more than 5 short URLs per day 29/36

30. Publishers(4/4)  Correlation between a user’s publish rate and total number of hits –As the number of URLs published by a poster increases, the expected hit rate drops  Spamming-type behavior  Only a few short URLs from each publisher enjoy high hit rates 30/36

31. Outline  Introduction  URL Shortening Services  Data Collection  The Web of Short URLs  Evolution and Lifetime  Publishers  Short URLs and Web Performance –Space reduction –Latency  Conclusion 31/36

32. Short URLs and Web Performance(1/3) Space reduction  Space gain for the short URL –URL shortening services are quite effective at reducing URL size  For roughly 50% of the URLs, 91% reduction in size is observed –In twitter trace, only 31% of long versions of short URL remained under the character limit 32/36

33. Short URLs and Web Performance(2/3) Latency  URL shortening services impose an additional overhead in the user’s web request  We periodically accessed the 10 most popular short URLs –Fb.me and ow.ly exhibit a bimodal behavior –Bit.ly appears to be the slowest but shows more consistent behavior 33/36

34. Short URLs and Web Performance(3/3) Latency  The redirection overhead of bit.ly –More than 50% of the accesses, the URL shortening redirection imposes a relative overhead of 54% –This additional delay turns out to be comparable to the final web page access time in a significant fraction 34/36

35. Outline  Introduction  URL Shortening Services  Data Collection  The Web of Short URLs  Evolution and Lifetime  Publishers  Short URLs and Web Performance  Conclusion 35/36

36. Conclusion  We have presented a large-scale study of URL shortening services –Exploring traces from services themselves and Twitter  Summary –Short URLs appear mostly in ephemeral media, with profound effects on their popularity, lifetime, and access patterns –Small number of URLs have a very large number of accesses –A large percentage of short URLs are not ephemeral –The most popular websites changes slowly over time –The web sites differ from the sites which are popular among the broader web community –URL shortening services are extremely effective in space gaining but increase the overhead to access the web page 36/36