A Survey on Context-Aware Computing : Past, Present, and Future

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A Survey on Context-Aware Computing : Past, Present, and Future. Sang- keun Lee Intelligent Database Systems Lab School of Computer Science & Engineering Seoul National University, Seoul, Korea. Center for E -Business Technology Seoul National University Seoul, Korea. Motivation. - PowerPoint PPT Presentation


<p>PowerPoint Presentation</p> <p>A Survey on Context-Aware Computing: Past, Present, and Future</p> <p>Center for E-Business TechnologySeoul National UniversitySeoul, KoreaSang-keun Lee</p> <p>Intelligent Database Systems LabSchool of Computer Science &amp; EngineeringSeoul National University, Seoul, KoreaCopyright 2008 by CEBTMotivation</p> <p>Context-Aware System</p> <p>Copyright 2008 by CEBTHistory of Context-Aware Computing:Context DefinitionTerm Context-aware appeared in Schilit and Theimer(1994)Authors describe context as location, identities of nearby people, objects, and changes to those objectsRyan et al. (1997) referred to context as the users location, environment, identity, timeDay (1998) : the users emotional state, focus on attention, location, and orientation, date and time, as well as objects and people in the environmentDey and Abowd (2000)Any information that can be used to characterize the situation of entities that are considered relevant to the interaction between a user and an application, including the user and the application themselvesCopyright 2008 by CEBTHistory of Context-Aware Computing:Application &amp; System, Context ModelActive Badge Location System (Wang et al., 1992)One of the first context-aware systemsForward phone calls to a telephone close to the userCouple of location-aware tour guidesAbowd et al., 1997; Sumi et al., 1998; Cheverst et al.,2000Providing information according to the users current locationWatson Project (Budzik and Hammond, 2000)W3C, RDF available (2000)IntelliZap (Finkelstein, 2001)Context Toolkit (Dey and Abowd, 2001)p2p architecture + centralized discoverer, attribute-value tuple/XML - Context aggregation/interpretation, historical context data, Context Ownership (Privacy)Hydrogen (Hofer, 2002)local/remote context, Object Oriented Model, process higher-level context abstraction in application layer</p> <p>Copyright 2008 by CEBTHistory of Context-Aware Computing:Application &amp; System, Context ModelGaia project (Romans)Extends operating system contepts to include context-awareness4-ary predicates in DAML+OIL, context processing is based on first-order logic operationGraphical Context Model: ORM (Hendricksen, 2003)Context Managing Framework (Koripaa, 2003) Centralized server CoBrA- Context Broker Architecture (Chen, 2003)COBRA-Ont(Ontology Model), Inference Engine, historical context data, Broker federation Avoiding bottleneck Context Knowledge base You can assert, delete, modify, query the stored data(API)Flexibile policy language to control context access called Rei (privacy)2004 W3C, OWL availableCopyright 2008 by CEBTHistory of Context-Aware Computing:Application &amp; System, Context ModelMarkup scheme model: Composite Capabilities/Preference Profile (CC/PP) (W3C, 2004)SOCAM(Service-Oriented Context-Aware Middleware) (Gu, 2004)Upper ontology, Domain-specific OntologyCASS (Fahy and Clarke, 2004)CORTEX (2004)Based on sentient object model sensor fusion to manage uncertainty of sensor dataGraphical Context Model: Context Modeling using UML (Sheng and Benatallah, 2004)CoCA (Ejigu, 2007)Enhanced CoCA (Ejigu, 2008)Using a hybrid context management model Relational Database, Ontology ToolsHeuristics for better performanceCopyright 2008 by CEBTHistory of Context-Aware Computing:Sensor DefinitionBurnett (2003) and Gustavsen (2002)External and internalHofer et al. (2002)Physical and logical</p> <p>Semantic Tech &amp; Context - 7Context that can be measured by hardware sensors, i.e,., locationa, light, sound, movement, touch, temperature or air pressure</p> <p>Context that can be captured by user interactions, i.e., the users goals, tasks, work context, emotional state</p> <p>Easier to senseCopyright 2008 by CEBTPractical Semantic Technology - 8</p> <p>Copyright 2008 by CEBTPractical Semantic Technology - 9</p> <p>Copyright 2008 by CEBTThe History in SummarySpecific Context Definition to General Context DefinitionNon-Flexible Context Models to Flexible and Extensible Context ModelDomain-specific Applications to General Frameworks</p> <p>Copyright 2008 by CEBTCategories of Context Aware ApplicationsSchilit (1994)Proximate SelectionA user interface technique where the located-objects that are nearby are emphasized or otherwise made easier to chooseAutomatic Contextual ReconfigurationsReconfiguration is the process of adding new components, removing existing components or altering the connections between componentsContextual Information and CommandsQueries on contextual information can produce different results according to the context in which they are issuedContext-Triggered ActionsContext-triggered actions are simple IF-THEN rules used to specify how context-aware systems should adaptSang-keun LeeContext-Aware / Personalized Contents PushSeamless Device SwitchingAutomatic Device ConfigurationDecision Support/SuggestionContext Aware User Interface</p> <p>11Context-aware computing applications (Schilit, B.; Adams, N.; Want, R.)Mobile Computing Systems and Applications, 1994. Proceedings., Workshop onVolume , Issue , 8-9 Dec 1994 Page(s):85 - 90Copyright 2008 by CEBTAn Example of Domain-dependent Applications: Cyberguide : A mobile context-aware tour guide (1997) Goalknow where tourist is, and what she is looking for predict and answer question she may poseprovide interaction with other people and environment</p> <p>Copyright 2008 by CEBTDesign Principles ArchitectureChen (2004) presents three different approaches on how to acquire contextual informationDirect sensor access devices with sensors locally built in Middleware infrastructure hiding low-level sensing details, more extensibleContext Server multiple clients access to remote data sourceWinograd (2001)Widgets a software component that provides a public interface for a hardware sensor, hiding low-level details of sensing, managed by widget managerNetworked services more flexible, discovery techniques are used, not as efficient as a widget architecture but provides robustnessBlackboard model data centric view, simplicity of adding new context sources (easy configuration)Architecture StylePeer to PeerLimitation of Memory Resource, CPU PerformanceOnly uses local built-in sensorsCentralized ApproachRobustness</p> <p>Baldauf, M., Dustdar, S., and Rosenberg, F. 2007. A survey on context-aware systems. Int. J. Ad Hoc Ubiquitous Comput. 2, 4 (Jun. 2007), 263-277. DOI= http://dx.doi.org/10.1504/IJAHUC.2007.014070Copyright 2008 by CEBTHydrogen (2002)Framework ArchitectureThree layerApplication layerManagement layerProviding and retrievingcontexts and sharingcontext informationwith other devices usingP2P communicationAdaptor LayerSeparating context storing, sensing from other layersResponsible to get information from sensorsProviding same context information to multiple applicationsAll application have access to all context data by querying the ContextServerAll layers are located on one deviceRobust against network disconnections, Peer to PeerObject-oriented Context Model</p> <p>Copyright 2008 by CEBTSOCAM Architecture (2004)Context providers, Context interpreter, Context database, Context-aware services, and Service locating service Architectural RequirementsA common context model that can be shared by all devices and servicesA set of services that perform context acquisition, context discovery, context interpretation and context disseminationUpper/Domain-specific Ontology</p> <p>15</p> <p>Copyright 2008 by CEBTThe Context Fabric (2004)Primarily concerned with privacy rather than with context sensing and processingprovides an architecture for privacy-sensitive systems, as well as a set of privacy mechanisms that can be used by application developersPrevious work on privacy has tended to focus on anonymity or on keeping information from hackersConfabs focus is in empowering people with choice and informed consent, so that they can share the right information, with the right people and services, in the right situation</p> <p>Copyright 2008 by CEBTThe CoCA Service Platform (2007)IDS Lab.17</p> <p>Interface ManagerManages a UI and interface between the CoCA platform and other modulesData SourceResponsible to provide necessary data to the core service (GCoM)Core ServiceResponsible to provide the core context aware service after reasoning on the componentsSupplementary ServiceKnowledge discovery &amp; Collaboration serviceThe Platform aims at acquiring and utilizing context information to provide appropriate servicesE.g) A cell phone is always set to vibrating mode when its holder is in the libraryIt filters and sends useful contexts to the context repositoryIt Keeps the rules in the rule repositoryIt consists of domain dependent/independent ontologyReasoning -&gt; Decision &amp; ActionInterpretation, AggregationCopyright 2008 by CEBTThe Enhanced CoCA Service Platform (2008)Enhanced version of CoCACombine the best of the relational approach and ontology approachSelective feature of loading only relevant context data into the reasoner using heuristics </p> <p>Copyright 2008 by CEBTSummary: Existing systems and frameworks</p> <p>Baldauf, M., Dustdar, S., and Rosenberg, F. 2007. A survey on context-aware systems. Int. J. Ad Hoc Ubiquitous Comput. 2, 4 (Jun. 2007), 263-277. DOI= http://dx.doi.org/10.1504/IJAHUC.2007.014070Copyright 2008 by CEBTCriteria</p> <p>Henricksen, K., Indulska, J., McFadden, T. and Balasubramaniam, S. (2005). Middleware for distributed context-aware systems. In: Robert meersman and Zahir Tari et al International Symposium on Distributed Objects and Applications (DOA), Agia Napa, Cyprus, 31 October - 4 November, 2005. Copyright 2008 by CEBTDiscussionDoes a context-aware system bother users? MS Office Assistant ClippyThree Levels of InteractivityPersonalizationThe majority of users use the default setting of change a small subset of the possible featuresPassive Context-awarenessPresenting the updated context to the userLet the user specify how the application should changeEx) mobile phone prompts the user with information about the time zone changeActive Context-awarenessChanging the content autonomously on the basis of measured sensor dataEx) Mobile phone that changes its time autonomously by new time zoneThe authors conclude that people are willing to give up partial control if the reward in usefulness is great enoughHow could we deal with the imperfect/probabilistic context data?Fuzzy LogicContext Data AbstractionWhat could be the Killer Application?What could we mine from the log data?Support RulesPeer to Peer vs. Centralized System</p> <p>L Barkhuus, A Dey, Is Context-Aware Computing Taking Control Away from the User? Three Levels of Interactivity Examined,2003Copyright 2008 by CEBTLayered Conceptual Framework with Core ComponentsFoundation Layer:SensorsData/Rule MiningRelational DatabaseNetworkSemantic Technology Layer:Ontology RepositoryInference Engine</p> <p>Service &amp; Application Design Layer: Context-Aware Services:Context AcquisitionDeviceCommunicationData Management &amp; MiningContext OntologyModelingContext Fusion &amp; AbstractionRule based Action TriggeringOntology DataStorage &amp; ManagementLow-levelData ModelingContext-Aware Personalized Contents PushSeamless Device SwitchingAutomatic Device ConfigurationDecision Support&amp; SuggestionContext Aware User InterfaceUbiquitousIntelligentSeamlessDomain-specific Context Data ModelingRuleDefiningServiceAlgorithm ImplementationPrivacy &amp; Security PolicyDefiningPrivateScalable</p> <p>Copyright 2008 by CEBTConclusionsWe talked aboutMotivationHistory of Context-aware ComputingCategories of Context-aware ApplicationsDesign PrincipleExamples of Context-aware SystemsCriteria &amp; DiscussionWhat will be the future Context-aware System?A Context-aware system withBetter scalability and performanceUtilizing historical context data (Rule mining, ...)Better Security policies and privacy protectionVirtual and logical sensor supportStandard communication protocol and context modelCopyright 2008 by CEBT</p>


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