Mikko Vapa, research student, mikko.vapa@jyu.fi With co-authors Pedro Tiago, Niko Kotilainen, Heikki Kokkinen and Jukk

1. Mobile Search – Social Network Search Using Mobile Devices1st IEEE International Peer-to-Peer for Handheld Devices WorkshopIEEE CCNC, Las Vegas, 12th 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. 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. 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. 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. 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. 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. 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. 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. User Interface

10. 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. 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. 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 • SearchingPortugal would give six results,but then theuser might continue thesearch via Lisboa tag andfinds theTrolley image

13. 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”