Slide 1

UbiBay Erfahrungsbericht zur praktischen Umsetzung eines Auktionssystems fr groflchige mobile multihop Ad-hoc- Netzwerke Hannes Frey, Daniel Grgen, Johannes K. Lehnert, Peter Sturm, Systemsoftware und Verteilte Systeme, Fachbereich IV Informatik, Universitt Trier Slide 2 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke2 03.04.2003 Metropolitan sized networking Mobile devices Wireless communication facilities Localized location computation Direct communication only within transmission range Unpredictable network topology changes due to mobility Network partitions Permanent link failures Supply and demand as a fundamental communication pattern Problem: Find an agreement among offerer and requester Problems and assumptions Request Offer Slide 3 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke3 03.04.2003 Possible solutions Flooding of the entire network Network load Network partitions Waiting for matching peers in transmission range User has to walk to the transmission range of a supplier Low probability to find a match Request Offer Slide 4 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke4 03.04.2003 The marketplace solution Basic idea Definition of a marketplace Devices acting on behalf of a user Walking to the marketplace Negotiating at the marketplace Walking back to the home zone Further components R O O O R R O R Request Offer R R R O O O Slide 5 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke5 03.04.2003 UbiBay A mobile auction system Auction at marketplaces Low value goods Direct neighborhood Agents Auction agent Controls the auction Discovery agent Lists all auctions at marketplace Bid agent Bids on behalf of a user 15 10 Slide 6 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke6 03.04.2003 UbiBay Security Issues Maximum bid is the most crucial part Security needs for low value goods? Using a PKI Securing the maximum bid Signed agents Secret sharing 4 4 MAX=4 4 4 4 4 4 4 *** MAX=4 3 4 5 00101101 10110011 01101110 Slide 7 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke7 03.04.2003 Middleware for mobile Applications Test applications: auction system, digital ride board, the SOUL application, games middleware components investigated at the moment Hardware Abstraction Agent Platform Agent Transport Marketplace-wide Communication Marketplace Localization Marketplace Creation A1A2A3S1S2S3 Application AgentsService Agents Slide 8 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke8 03.04.2003 Agent Transport To and from marketplaces Geographic routing e.g. greedy algorithm Additional: course information Messages can be carried over network partitions Message duplication to avoid message losses Sender keeps messages until reception is acknowledged Duplicated messages can be detected on the marketplace Losses are still possible Device crash S D Slide 9 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke9 03.04.2003 Marketplace-wide Communication More reliable communication High device density Network partitions are rare Message loss can be detected Agents stay longer at market Discovery Broadcast only in a small region Discard messages outside Flooding or neighbor knowledge broadcasts Negotiation Topology-based routing Broadcasts as above Only simple solutions are implemented yet Slide 10 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke10 03.04.2003 Marketplace Management Creation On demand Loadmonitoring: split and join Localization Information dissemination Super-Marketplaces Collecting information about device accumulation Hotspot detection enhanced position-based routing Slide 11 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke11 03.04.2003 Further Aspects Service agents Creation Jobs Load Monitoring Duplicate detection Ticket Service Caching of data Running auctions Public bill-board L D T Slide 12 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke12 03.04.2003 Simulation of mobile applications Focused on Applications High level of abstraction Changeable Network and Mobility-Models Visualization One implementation for both simulation and real hardware Scalability Up to 10000 Devices 10km x 10km area Simulated user interaction? Slide 13 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke13 03.04.2003 Evaluation of mobile applications Simulation components on real hardware (Toshiba, iPAQ) WLAN with UDP unicast/broadcast Device discovery by periodic broadcasts Use of GPS receivers Requires Java VM (J9 IBM) User interaction by Java GUI Replacement for simulated user interaction Evaluation methods Hybrid: PDA attached to simulation (RMI) Evaluation solely on real hardware Advantages of hybrid approach No thousands of real devices needed Replay of specific scenarios Nevertheless get a feeling for the real application Slide 14 UbiBay: Ein Auktionssystem fr mobile multihop Ad-hoc-Netzwerke14 03.04.2003 CeBIT Demonstration