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Service Discovery in Ubiquitous and Pervasive Environments

Service Discovery in Ubiquitous and Pervasive Environments. Presented by Knarig Arabshian PhD candidacy exam October 26, 2004. Overview. Introduction History of service discovery, challenges Components Description, distribution, query Existing systems

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Service Discovery in Ubiquitous and Pervasive Environments

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  1. Service Discovery in Ubiquitous and Pervasive Environments Presented by Knarig Arabshian PhD candidacy exam October 26, 2004

  2. Overview • Introduction History of service discovery, challenges • Components Description, distribution, query • Existing systems Mainstream, ad-hoc, location aware, semantic, Internet-scale http://www.cs.columbia.edu/~knarig/candidacy/candidacyList.html

  3. Query Distribution Consumer Provider Directory Service description What is service discovery? Service vs resource discovery

  4. History of resource discovery [6] A comparison of internet resource discovery approaches, 1992 [7] Resource location protocol, 1983

  5. Motivationfor new service discovery protocols Static resource information (whois, RLP, X.500) Automatic discovery of LAN network services (SLP, Jini, UPnP) • Automatic • Automatically announce or register service instead of manually entering information. • LAN services • Printer, FAX machine, … [8] Protocols for service discovery in dynamic and mobile networks, IJCR (Journal), 2002

  6. Motivationfor new service discovery protocols Static resource information (whois, RLP, X.500) Automatic discovery of LAN network services (SLP, Jini, UPnP) Internet scale discovery (INS/Twine, Ninja) • Wide-area service discovery • Multiple attributes • Auto configured and rapid availability • Automated discovery without user input • Policy support by agent • Scalable

  7. Motivationfor new service discovery protocols • Pervasive computing • User intent • Client thickness • Cyber foraging (living off the land) • Context awareness • Proactive vs transparent • Ad hoc networks Static resource information (whois, RLP, X.500) • Me-services • Personal and pervasive • Semantic service discovery • Dynamic service composition • Distributed trust management • Profile driven management Automatic discovery of LAN network services (SLP, Jini, UPnP) Internet scale discovery (INS/Twine, Ninja, CoolTown) • Semantic web • Express meaning • Knowledge representation using ontologies • Improving accuracy of web search • Agents exchange ontology information to perform service discovery Ad hoc discovery without infrastructure (Konark, DEAPSpace) Location aware discovery (Agents2Go, Splendor) Semantic service discovery (Ronin, DReggie) [1] The semantic web, Scientific American, 2001 [2] Pervasive computing: vision and challenges, IEEE personal communications, 2001 [4] Me-services: a framework for secure and personalized discovery…, 2002

  8. Components • Directory repository • Centralized • Distributed • Hierarchical • Structured P2P • Ad hoc • Service description • Attribute/value • Tree-like • XML • Ontologies (DAML) Consumer Provider Directory

  9. Components • Announcement • Register • Multicast/broadcast • Query/Service Access • Syntax • Ontology • Programming language dependency Consumer Provider Directory References for mainstream protocols: [9] The Service Location Protocol, IEEE Internet Computing, 1999 [11] Jini architecture specification, Sun Microsystems, 2003 [12] Understanding Universal Plug and Play white paper, Microsoft, 2000 [13] Specification of the Bluetooth system, Bluetooth [14] Salutation architecture specification version 2.1, The Salutation Consortium, 1999

  10. Mainstream protocols

  11. Mainstream protocols

  12. More protocols…mSLP: mesh-enhanced SLP • Fully-meshed peering DA architecture with one or more scopes in common • Reliability • Scalability • Backward Compatibility- extends DA Advertisement with a “mesh-enhanced” attribute [10] mSLP – mesh enhanced SLP, ICCCN, 2000

  13. More protocols…UDDI: Universal Description, Discovery and Integration • UDDI specifications and schemas used to build discovery services on Internet • Provide consistent publishing interface • Allow programmatic discovery of services • Who: Sun, IBM, Microsoft partnership [15] UDDI technical white paper, 2000

  14. More Protocols…UDDI: Universal Description, Discovery and Integration Consumers access services by using the Programmer’s API built on SOAP Services described in XML and published using Publisher’s API Business registry contains yellow, white, green pages

  15. Design for ad hoc networks • No central directory service • Limited use of network/device resources • Reliability • Pervasive • Distributed Konark DeapSpace GSD Allia

  16. Design for ad hoc networks • Main entities • Node acts as client+server • Service announcement • Flooding • On device join • Periodically, delta announcement (Konark) • Slotted (DEAPSpace uses slotted+periodic) • Cache advertisements • TTL

  17. Design for ad hoc networks • Service description • What is described? • service name, type, attribute, keywords, properties and functions • Service hierarchy - tree like structure (Konark, GSD) • Interface format, e.g., function prototype. • How is it described and stored? • WSDL file (Konark) • Data structures similar to ASN.1 (DEAPSpace) • Encoder/decoder • Ontology: DAML+OIL (GSD)

  18. Design for ad hoc networks • Access to the service • RPC • SOAP/HTTP (Konark) • Specific Interface, e.g., function prototype • Encoder/decoder (DEAPSpace) • Query formation • Path based or syntax based • Request routing • Policy based (Allia) • Group based (GSD)

  19. Contributions [17] Konark – a service discovery and delivery protocol for ad hoc networks, WCNC, 2003 [18] DEAPspace – transient ad hoc networking of pervasive devices, Computer Networks, 2001 [19] GSD: a novel group-based service discovery for MANETS, MWCN, 2002 [20] Allia: alliance-based service discovery for ad-hoc environments, WMC, 2002

  20. Design for semantic ontologies • Use of semantic ontologies • Inexact/exact querying • More powerful reasoning engines and AI tools • Enhancing current service location protocols Find me the best cab service… Ronin Agent Framework DReggie

  21. Ronin Agent Framework Built on top of Jini Jini Prolog engine Agent-oriented development Java classes and interfaces printing service, restaurant service Communicate with other agents using Agent Communication Language Agent deputy Mediates agent communication Represents owner agent in the network Located in the Jini Lookup Service Dreggie for M-commerce Enhance Jini Matching mechanism of Jini’s LookupService Prolog reasoning engine used for matching Service registration along with interface registration Services register with DAML description and interface DAML gives hierarchical description of services Contributions [21] Dynamic service discovery for mobile computing, BSJCC (Journal), 2001 [22] Dreggie: semantic service discovery for M-commerce applications, 2001

  22. Location-aware service discovery • Where is the closest Italian restaurant • to me? • Location sensing • Nomadic users • Handy devices CoolTown, Splendor, Agents2Go

  23. CoolTown • Every service (e.g., printer) has a web server, and a tag. • Users walk in and receive URL from tag beacons • Connect to the URL which describes the service and can invokes it • Place manager maintains resources in a place, with web interface (HTML and XML) • Resources can be grouped. • Also acts as a resolver for some places

  24. Splendor • Tag-based location aware • Tag label location and people • Proxies • Enhanced security • Service management (registration, security) Trusted servers managing services Bootstrapping using multicast

  25. Agents2Go PalmApp (with CDPD modem) Cell tower Location identified by cell tower id register Restaurant agent or other services User query Initial query form Brokers Area 2 User query Locator Area 3 Maps geographic area to broker Agents2Go Server

  26. Contributions • Attach web URL to services and periodically broadcast (CoolTown) • Intermediate trusted proxy for security and service management (Splendor) • Localized brokers store services in the location and are mapped to based on the user location (Agent2Go) [23] Agents2Go: an infrastructure for location-dependent service discovery, 2001 [24] Splendor: a secure, private, location-aware service discovery protocol, 2003 [25] A web-based nomadic computing system, Computer Networks, 2001

  27. Internet-scale discovery • Construct scalable, robust services • Huge throughput demands and availability • Interoperability • Efficiency • Fault tolerance INS/Twine, Ninja/SDS, WSPDS

  28. INS/Twine root • Uses Chord • structured peer to peer system • Lookup in Log(N) • Service Propagation • Resource state changes, update is propagated • Periodic refreshing of resource information • edge resolvers attached to clients update frequently • Internal resolvers infrequently res subject resolver camera traffic man model ACompany AModel Resource is a camera, manufactured by ACompany and filming traffic. StrandMapper Hash(strand) Distributed hash table (Chord). KeyRouter maps to Chord. [30] INS/Twine: a scalable p2p architecture for intentional resource discovery, 2002

  29. Ninja Services running on clusters of workstations Secure Service Discovery Service (SDS) • Uses XML to encode service descriptions • Certificate Authority and Capability Managers for security • Servers dynamically organize themselves into hierarchies for scalability • Filters query upwards to avoid overloading one node (Bloom filter) Distributed data structures A chain across proxies and bases to find better service Stateless and soft-state proxy Heterogeneous devices and sensors [28] The ninja architecture for robust Internet-scale systems and services, JCN, 2001 [27] An architecture for a secure service discovery service, MobiCom, 1999

  30. Context attributes provided by services Distance to server Server load Service channel Attribute-value pair service description Localized Service Propagation propagate upward with attenuation factor of service attributes Query Routing Overlay hierarchy Multi-tier ubiquitous service discovery protocol Global Services Registry-gateway to global network Brokering Agent-recommends appropriate service Global Services [26] A multi-tier ubiquitous service discovery protocol, Mobisys, 2003 Domain Hierarchy

  31. WSPDS: Web Services P2P Discovery Service • Servent: Server/Client • DAML ontology for service description • Querical data network • Probabilistic flooding • Each node defined by content • Node links to other nodes of smiliar content • Semantic matching algorithm used to choose neighbor [29] WSPDS: web services p2p discovery service, ISWS, 2004

  32. Contributions • INS/Twine: structured P2P lookup on strands • Ninja/SDS: query filtering and service aggregation • Multi-tier Ubiquitous SDP: context attributes, hierarchical, localized service propagation • WSPDS: QDN, DAML for service description

  33. Conclusions • Service discovery for different scenarios in ubiquitous and pervasive environments: ad-hoc, location-aware, semantic and Internet-scale, and combinations of these • Tackle problems in service distribution, query and description • Not much work done in semantic service discovery

  34. References • T. Berners-Lee, J. Hendler, and O. Lassila, The Semantic Web, Scientific American , May 2001 • M. Satyanarayanan, Pervasive Computing: Vision and Challenges, IEEE Personal Communications , August 2001. • M. Weiser, The computer for the twenty-first century Scientific American, pp 94-103, September 1992 • Anupam Joshi, Tim Finin, and Yelena Yesha, Me-Services: A Framework for Secure and Personalized Discovery, Composition and Management of Services in Pervasive Environments, in Web Services, E-Business, and the Semantic Web, C. Bussler, R. Hull, S. McIlraith, M.E. Orlowska, B. Pernici, J. Yang (Eds.), LNCS 2512, p. 248 ff., Springer, ISBN:3540001980, December 2002 • J. Rosenberg, E. Guttman, R. Moats, H. Schulzrinne, WASRV Architectural Principles Internet Draft, Internet Engineering Task Force, Feb. 1998. Work in progress. • Michael F. Schwartz, Alan Emtage, Brewster Kahle, and B. Clifford Newman. A comparison of internet resource discovery approaches, Computing Systems, 5(4):466-493, Fall 1992. • M. Accetta, Resource Location Protocol RFC 887, Internet Engineering Task Force, December 1983. • C. Lee, S. Helal, Protocols for Service Discovery in Dynamic and Mobile Networks, International Journal of Computer Research, Volume 11, pp 1-12, 2002 • Erik Guttman, The Service Location Protocol, IEEE Internet Computing July 1999. • Weibin Zhao, Henning Schulzrinne and Erik Guttman, "mSLP - Mesh-enhanced Service Location Protocol", International Conference on Computer Communications and Networks (ICCCN'00), October, 2000. • Jini Architecture Specification, Sun Microsystems, June 2003 • Understanding Universal Plug and Play White Paper, Microsoft Corporation, June 2000. • Specification of the Bluetooth System, Bluetooth (www.bluetooth.org), pp 113-156 • Salutation Architecture Specification Version 2.1, The Salutation Consortium, 1999 • UDDI Technical White Paper, UDDI (Universal Description, Discovery and Integration), September 2000. • A. Gulbrandsen, P. Vixie, L. Esibov, A DNS RR for specifying the location of services (DNS SRV) RFC 2782, Internet Engineering Task Force, February 2000.

  35. References • S. Helal, N. Desai, V. Verma and C. Lee, Konark--A Service Discovery and Delivery Protocol for Ad-hoc Networks, Proceedings of the Third IEEE Conference on Wireless Communication Networks (WCNC), New Orleans, March 2003. • R. Hermann, D. Husemann, M. Moser, M. Nidd, C. Rohner, A. Schade, DEAPspace--Transient ad hoc networking of pervasive devices, Computer Networks Volume 35 pp 411-428, 2001 • D. Chakraborty, A. Joshi, , GSD: A Novel Group-based Service Discovery Protocol for MANETS, 4th IEEE Conference on Mobile and Wireless Communications Networks (MWCN 2002). Stockholm. Sweden. September. 2002 • Olga Ratsimor, Dipanjan Chakraborty, Sovrin Tolia, Deepali Kushraj, Anugeetha Kunjithapatham, Gaurav Gupta, Anupam Joshi, Timothy Finin, Allia: Alliance-based Service Discovery for Ad-Hoc Environments, Second ACM International Workshop on Mobile Commerce, in conjunction with Mobicom 2002, Sep 28, 2002, Atlanta GA, USA • H. Chen, A. Joshi, T. Finin. Dynamic Service Discovery for Mobile Computing: Intelligent Agents Meet Jini in the Aether, Baltzer Science Journal on Cluster Computing, Vol. 4, No. 4, March 2001 • D. Chakraborty, F. Perich, S. Avancha, and A. Joshi. DReggie: Semantic Service Discovery for M-Commerce Applications In Workshop on Reliable and Secure Applications in Mobile Environment, Symposium on Reliable Distributed Systems, October 2001. • O. Ratsimor, V. Korolev, A. Joshi, T. Finin. Agents2Go: An Infrastructure for Location-Dependent Service Discovery in The Mobile Electronic Commerce Environment ACM Mobile Commerce Workshop, July, 2001 • F. Zhu, M. Mutka, and L. Ni, Splendor: A Secure, Private, and Location-aware Service Discovery Protocol Supporting Mobile Services 1st IEEE Annual Conference on Pervasive Computing and Communications, IEEE Computer Society Press, Fort Worth, Texas, 2003 • T. Kindberg and J. Barton, A Web-based nomadic computing system, Computer Networks, Esevier. Vol 35, No. 4, March 2001, 443-456 • C. Lee and A. Helal, A Multi-tier Ubiquitous Service Discovery Protocol First ACM International Conference on Mobile Systems and Applications (Mobisys), May 2003 • S.E. Czerwinski, B. Zhao, T. Hodes, A. Joseph, and R. Katz, An Architecture for a Secure Service Discovery Service, Fifth Annual International Conference on Mobile Computing and Networks (MobiCom '99), Seattle, WA, August 1999, pp. 24-35 • S. D. Gribble, M. Welsh, R. von Behren, E. A. Brewer, D. Culler, N. Borisov, S. Czerwinski, R. Gummadi, J. Hill, A. Joseph, R. H. Katz, Z. M. Mao, S. Ross, and B. Zhao, The Ninja architecture for robust Internet-scale systems and services, Journal of Computer Networks, vol. 35, no. 4, March 2001. • Farnoush Banaei-Kashani, Ching-Chien Chen, Cyrus Shahabi, WSPDS: Web Services Peer-to-peer Discovery Service , International Symposium on Web Services and Applications(ISWS'04) , Las Vegas, Nevada, USA, June, 2004 • M. Balazinska, H. Balakrishnan, D. Karger, INS/Twine: A Scalable Peer-to-Peer Architecture for Intentional Resource Discovery, International Conference on Pervasive Computing August 2002

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