1. UNIVERSITY OF JYVÄSKYLÄ Mobile Search – Social Network Search Using Mobile Devices 1 st IEEE International Peer-to-Peer for Handheld Devices Workshop IEEE CCNC, Las Vegas, 12 th of January 2007 Mikko Vapa, research student, mikko.vapa@jyu.fi With co-authors Pedro Tiago, Niko Kotilainen, Heikki Kokkinen and Jukka K. Nurminen (Nokia P2P Team) Department of Mathematical Information Technology University of Jyväskylä, Finland www.mit.jyu.fi/cheesefactory

2. UNIVERSITY OF JYVÄSKYLÄ Background Mobile phones' computational power has been improving approaching the capabilities of general purpose computers Nowadays it is possible to host a web site on a mobile device It is also expected that the number of mobile web sites will outnumber the static web servers Recently, there has been a growing interest in how to explore the mobile phone capabilities in the web search context and how to merge them with existing phone functionalities [Johan Wikman, Ferenc Dosa, and Mikko Tarkiainen. Personal website on a mobile phone. Technical report, Nokia Research Center, 2006]

3. UNIVERSITY OF JYVÄSKYLÄ Mobile Search Mobile Search is a system for social network search on a mobile device Prototype was implemented on top of Drupal content management system running on Mobile Apache/Raccoon mobile web server Based on pure peer-to-peer architecture offers scalability, efficiency, resilience to failures and privacy at a higher degree than centralized solutions [Choon-Hoong, Nutanong and Buyya, Peer-to-Peer Networks for Content Sharing, Peer-to-Peer Computing: Evolution of a Disruptive Technology, 2005]

4. UNIVERSITY OF JYVÄSKYLÄ Features Allows executing searches to the contents of mobile devices using a web interface Searches through social network defined by the addressbooks of the mobile devices Manages access rights for different kind of contents (calendar data, photos, blogs etc.) using motto: I only display what I want to who I want Can also search normal Drupal websites

5. UNIVERSITY OF JYVÄSKYLÄ New Search Concepts Manual multi-hopping –Users search one graph level of their social network at a time usually starting from their neighbors –Every time a user issues a search query the mobile device forwards it to all the neighbors of the user –The neighbors answer back by returning a result set and a list of their neighbors –If the user who issued the query is not satisfied by the results he can always ask new results from the next level neighbors as long as there are non-visited nodes in the network Automatic multi-hopping –A sorting algorithm decides which of the non-visited nodes are queried further thus avoiding the need for user decision –Automatically sorting the non-visited nodes leads to tradeoff between search accuracy and easiness of searching suggesting that both manual and automatic multi-hopping should be available for the user

6. UNIVERSITY OF JYVÄSKYLÄ Benefits Compared to centralized web search engines: –Mobile Search provides access to rare personal data relevant to people close in the social network –The contents indexed by Mobile Search might not be referenced anywhere but still they are searchable –Real-time - Does not provide outdated links –Highly distributed, decentralized and no single point of failure –Mobile Search can utilize websites internal search functionalities –Search is executed within the limits of access control rights providing means to search non-public data (internal search among friends etc.) –However, social network search is not suited to find popular content But, it's a powerful mechanism in restricted topic set environment [Mislove, Gummadi, and Druschel, Exploiting social networks for internet search, Proceedings of the 5th Workshop on Hot Topics in Networks, 2006]

7. UNIVERSITY OF JYVÄSKYLÄ Drupal Prototype of Mobile Search Drupal is an open-source content management system for managing and publishing several types of content Prototype is logically divided to local web search engine and metacrawler parts –Local web search engine is a search service, which manages the search index of the mobile device –Metacrawler is a search service, which uses other local web search engines for getting the results and combines different result sets into one Metacrawler was built as a weakly coupled component on top of Drupal local web search engine –Features automatic multi-hopping and result interleaving –Differs from blog aggregators because content is being searched and a set of queried nodes is not fixed

8. UNIVERSITY OF JYVÄSKYLÄ Drupal Prototype of Mobile Search Drupal tac_lite module and Drupal module were used as fundamental elements in the prototype –These modules allow setting content access rules and to process user authentication in distributed fashion without any central servers An extra component that allows to do queries to local mobile phone content such as location, address book and meeting data was implemented –This feature was built as a simple proof of concept –However, the prototype is also able to gather search results from unmodified Drupal web sites

9. UNIVERSITY OF JYVÄSKYLÄ User Interface

10. UNIVERSITY OF JYVÄSKYLÄ Technical Limitations The current implementation is single threaded because Mobile Apache/Raccoon web server doesn't support multiple threads [Wikman, Mobile web server - eurooscon presentation, 2006] [Wikman and Dosa, Providing http access to web servers running on mobile phones, Technical report, Nokia Research Center, 2006] Single-threaded nature of the metacrawler is a drawback This has a negative impact on response time because site crawling is done in a serial way A multi-threaded implementation would speed up the system considerably

11. UNIVERSITY OF JYVÄSKYLÄ Future Work Query forwarding/node sorting algorithms should be considered though in a different setting than previous studies –Algorithms like K-Random walk, Expanding Ring and hybrids using NeuroSearch neural network should be considered Requires collecting some search usage statistics Also one interest is the usability of search results, and new paradigms of displaying different types of information and user interaction –Web 2.0 may not be fully suitable for mobile device paradigm of interaction –This could also be an excellent opportunity to use a query language applied to this type of systems for example an adaptation of webSQL [Mendelzon et al., Querying the world wide web, Int. J. on Digital Libraries, 1997] Would likely create a bigger interoperability and homogenization in this type of systems with easier deployment of new functionalities

12. UNIVERSITY OF JYVÄSKYLÄ Future Work Mobile Search can be extended by creating different ways of accessing the content, one entry point could be tags Tags work as links between content categorized similarly At each hop the user gets the list of contents tagged in a similar way by nodes in its neighborhood Searching Portugal would give six results, but then the user might continue the search via Lisboa tag and finds the Trolley image

13. UNIVERSITY OF JYVÄSKYLÄ Conclusions Mobile Search complements traditional web search engines It gives the user means to explore the neighbors contents by traveling to the friends network topology It covers a multitude of environments not covered by the centralized solutions One of the main advantages in relation to current centralized social network sites is the possibility to manage the site without interference from an external entity –Currently in a normal social network site a user can only display or use modules made available by a third entity –With Mobile Search approach it is possible to merge different social network sites that cover different topics and create a social network "melting pot