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Enhancing Interactive Web Applications in Hybrid Networks

Enhancing Interactive Web Applications in Hybrid Networks. Aruna Balasubramanian Brian Neil Levine Arun Venkataramani University of Massachusetts, Amherst. Motivation. Mobile users increasingly want to access network applications on the go. Technologies. 3G. Application support.

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Enhancing Interactive Web Applications in Hybrid Networks

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  1. Enhancing Interactive Web Applications in Hybrid Networks Aruna Balasubramanian Brian Neil Levine Arun Venkataramani University of Massachusetts, Amherst

  2. Motivation • Mobile users increasingly want to access network applications on the go Technologies 3G Application support Opportunistic WiFi Cost

  3. Our work • How can we support a broader class of interactive applications using opportunistic WiFi access? 1. Mobile-to-Infrastructure contacts 2. Mobile-to-Mobile contacts Internet

  4. Application design space Delay Tolerant Email, bulk transfer m2m contacts useful ~1s Interactive Web? Web browsing, Web search Connection duration with AP ~60s ??? VoIP ~3600s ~1s ~60s ~3600s Disconnection duration with AP m2i contacts useful

  5. Outline • How can opportunistic mobile-to-Infrastructure (m2i) contacts be used to support web search? • Can performance be improved by simultaneously leveraging mobile-to-mobile (m2m) contacts? • What is the performance of web search using opportunistic WiFi access?

  6. Web search process <your favorite search engine> Retrieving…. Retrieving….

  7. Challenges: Intermittent connectivity <your favorite search engine> Retrieving….

  8. Thedu: Adapting Web search for intermittently connected networks • Use aggressive prefetching web pages to convert interactive process to transactional • Prioritize prefetched web pages during bandwidth limited connection

  9. 1. Aggressive prefetching Thedu Proxy Internet

  10. 1. Aggressive prefetching Google, Yahoo, Live , Ask, …. Related work • Use prefetching to improve availability[Coda91, Jiang98, Chandra01] • Proxy-based to mask disconnections [Seth06,Ott06] Store query Queries from mobile node Interface Snippets Prefetch Web pages returned to mobile node Prioritized web pages

  11. 2. Prioritizing useful web pages • How many of these web pages are useful? • How many web pages to prefetch? • How to compare web pages from different queries? <your favorite search engine>

  12. How many to prefetch and how many web pages are useful? • 80% users are interested in top 20 web pages • Thedu: Only prefetch webpages for top 20 url snippets • For some queries (homepage), there is only a single useful response • E.g., query “mobicom 2008” likely needs one response “http://www.sigmobile.org/mobicom/2008/” • Thedu: Identify homepage queries and send only one relevant web response

  13. Homepage versus Non-homepage queries • Mobicom 2008 • <url> www.sigmobile.org/mobicom/2008 </url> • <snippet> MobiCom 2008, the 14th Annual International Conference on Mobile, </snippet> • <title> ACM Mobicom 2008 </title> • Oil prices summer • <url> www.eia.doe.gov/steo</url> • <snippet> Residential natural gas prices over the same period are projected to ,</snippet> • <title> EIA - Short-Term Energy Outlook </title>

  14. Thedu’s query-type classifier Thedu’s query-type classifier accuracy: 88%

  15. How to compare web pages from different queries? • Today’s search engine rank web page for a single query using relevance scores • Scores not comparable across queries … … • Thedu: Aggressive prefetching • Prefetch top 20 URLs for each query • Identify home page queries and return only 1 relevant web page in expectation • Prioritize the remaining web pages across queries by normalizing relevance scores q2 Queries q1, q2 q1 Thedu’s query normalization technique …

  16. Outline • How can intermittent mobile-to-Internet (m2i) connectivity be used to support web search? • Can performance be improved by simultaneously leveraging mobile-to-mobile (m2m) contacts? • What is the performance of web search using opportunistic WiFi access?

  17. Leveraging opportunistic m2m contacts When useful? When meeting opportunities are skewed Why useful? Because of decreasing marginal utility of web pages Internet

  18. Should nodes download their own web pages or route for others? • Thedu uses utility-based routing. X W … … Y … … y1 w3 x2 x1 Sorted according to utility y2 x2 w2 w2 x1 w1 w1 y1

  19. Utility computation: IR meets networking Goal: Maximize number of relevant responses delivered within a deadline • Utility of routing X or Y’s web page P(web page is relevant) x P(W can deliver the web page to destination within deadline) • Utility of downloading own web page P(web page is relevant) x P(web page will NOT be delivered to W within deadline if the opportunity is missed) X W Y

  20. m2m routing between mobile nodes • Deliver web pages destined to peer • Route other web pages using similar utility-based routing • Exploit query locality by caching popular web pages X W Thedu leverages m2m contacts 1. Using a utility-driven routing protocol 2. Exploiting caching

  21. Outline • Can intermittent mobile-to-Internet (m2i) connectivity be used to support web search? • Can performance be improved by simultaneously leveraging mobile-to-mobile (m2m) contacts? • How does Thedu perform in practice?

  22. Evaluation goals • Does Thedu improve performance of web search for opportunistic WiFi networks? • Is there a benefit for leveraging m2m contacts? Evaluation based on deployment of Thedu on DieselNet testbed and trace-driven simulations

  23. Evaluation tools: Networking and IR DieselNet Testbed at UMass 10 GB web collection, Large user study Search engine

  24. DieselNet: Both m2i and m2m contacts m2m meeting m2i meeting

  25. Web search deployment results Relevant Web pages delivered

  26. Delay in receiving relevant web page

  27. Effect of m2i meeting frequency on web search performance Trace-driven: Nov, 2007 Deployment: March, 2007

  28. Leveraging m2m contacts • On DieselNet, leveraging m2m contacts provide little benefit • Ratio of m2i versus m2m contacts is 20:1 • Our analytical model confirms result • Leveraging m2m routing is useful only if AP density is low

  29. Leveraging m2m contacts: Sparse AP • Leveraging m2m contacts • provides throughput benefit, but not delay • does not improve performance of interactive applications, even in sparse AP scenarios

  30. Conclusions • Thedu enables interactive web search application for intermittently connected networks • Leveraging m2m contacts only provides throughput benefits and only when AP density is low • Deployment of Thedu on DieselNet shows 3 times improvement in number of relevant web pages trace.cs.umass.edu

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