1. 7DS Peer-to-Peer Information Dissemination and Prefetching Architecture Stelios Sidiroglou-Douskos CS Seminar –Timo Ojala June 10, 2004

2. What is 7ds? Message-based application-layer service propagates information objects among mobile nodes that are within high-speed wireless range Carry data using mobile nodes To and from infrastructure networks Scales with the user population in a given area No infrastructure planning or deployment

3. 7DS approach Data sharing among mobile hosts in a peer to peer fashion. 7DS can coexist with other methods for data access, e.g. via FIS or BS to the Internet. 7DS as extension of infrastructure and ad-hoc networks

4. 7ds applications Wireless web caching Cheaper, faster links Emergency Infrastructure “I’m alive” messages, rescue info Wireless peer-to-peer sharing Maps, schedules, email Wireless mobile sensors Too far to directly communicate Vehicle Transportation Leverage local data

5. Basic idea Device wants to get an object Web page, map, local weather Obtain from peer within range Periodically query for object Device wants to send an object Email, SMS, I-am-alive Pass to nearby peer

6. Architecture Data access engine 802.11, Bluetooth Cache manager Content cache, reputation, popularity Search engine Keyword searching, indexing Decision maker Periodic, power-save, forwarding

7. 7ds Architecture

8. HTTP Architecture

9. Communication Protocol

10. Example

11. Object Relay propagate to other pedestrians 7DS MTA encrypt message; encrypt headers with 7DS public key Periodically advertise presence Relay location-based information (velocity, destination, available buffer size) Select candidate nodes to relay message Push object to candidate nodes

12. Applications for message passing Email objects Relaying SMS messages in congested/damaged areas Message relaying in sensor networks Traffic management information relaying

13. Pager as feedback channel MTA PL-900 POCSAG SNPP (RFC 1861) FLEX 1600-6400 b/s “message 42 delivered” remove from cache

14. Conclussions 7DS as extension of infrastructure and ad-hoc networks Combine benefits of low bit-rate, but ubiquitous and high bit-rate, but sparse networks