Context-Awareness in Mobile Environments Gruia-Catalin Roman Mobile Computing Laboratory Department of Computer Science and Engineering 7 June 2002 (Philadelphia,

Context-Awareness in Context-Awareness in Mobile Environments Mobile Environments

Gruia-Catalin RomanGruia-Catalin Roman

Mobile Computing LaboratoryMobile Computing Laboratory

Department of Computer Science and EngineeringDepartment of Computer Science and Engineering

7 June 2002 (Philadelphia, PA)7 June 2002 (Philadelphia, PA)

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MOBILE COMPUTINGMOBILE COMPUTING

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Trends in Mobile ComputingTrends in Mobile Computing

TechnologyTechnology MiniaturizationMiniaturization Wireless communicationWireless communication JavaJava

SocietySociety Ubiquitous accessUbiquitous access Increasing levels of mobilityIncreasing levels of mobility Computing and communication melting into the fabric of societyComputing and communication melting into the fabric of society

• InfrastructureInfrastructure

• EnterprisesEnterprises

• PeoplePeople

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Physical MobilityPhysical Mobility

Fixed networkFixed network Nomadic computingNomadic computing Ad hoc computingAd hoc computing

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Research ImplicationsResearch Implications

New design constraintsNew design constraints Frequent disconnectionFrequent disconnection Unpredictable movementUnpredictable movement Asymmetric bandwidthAsymmetric bandwidth Limited resourcesLimited resources Short battery lifeShort battery life

Interesting opportunitiesInteresting opportunities Spatial knowledgeSpatial knowledge Movement profileMovement profile

Increased demandsIncreased demands Reasoning about behaviorReasoning about behavior Connectivity maintenanceConnectivity maintenance AdaptationAdaptation

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Logical MobilityLogical Mobility

Code on demandCode on demand Remote evaluationRemote evaluation Mobile agentsMobile agents

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Research TrendsResearch Trends

Code on demand is made popular by JavaCode on demand is made popular by Java Mobile code languages (e.g., Oblique, Facile, Mobile code languages (e.g., Oblique, Facile,

Telescript) are losing groundTelescript) are losing ground Mobile agent systems (e.g., Agent TCL) are an Mobile agent systems (e.g., Agent TCL) are an

emerging new technologyemerging new technology Middleware is growing in practical importanceMiddleware is growing in practical importance

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Mobility ParadigmsMobility Paradigms

Continued access to remote resourcesContinued access to remote resources Delegation to mobile agentsDelegation to mobile agents Disconnected operationDisconnected operation Ad hoc grouping of people and devicesAd hoc grouping of people and devices Mass mobilityMass mobility

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Ad Hoc Network ChallengeAd Hoc Network Challenge

No fixed network infrastructureNo fixed network infrastructure Transient interactionsTransient interactions Decoupled computingDecoupled computing Open environmentOpen environment Physical and logical mobilityPhysical and logical mobility Frequent disconnectionsFrequent disconnections Limited guaranteesLimited guarantees

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Sample ApplicationsSample Applications

Highway information managementHighway information management Disaster responseDisaster response Military applicationsMilitary applications Contamination zone explorationContamination zone exploration Wireless anywhere classroomWireless anywhere classroom Cave and mine explorationCave and mine exploration Self-organizing office and factorySelf-organizing office and factory Video games in physical spacesVideo games in physical spaces

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Mobile Computing LaboratoryMobile Computing Laboratory

Rapid development of dependable mobile Rapid development of dependable mobile applications over ad hoc networksapplications over ad hoc networks

Formal models: Formal models: • precise semantics and analysisprecise semantics and analysis

Coordination ModelsCoordination Models• rapid developmentrapid development

Middleware: Middleware: • easy disseminationeasy dissemination

Algorithms: Algorithms: • feasible implementationfeasible implementation

Applications: Applications: • empirical evaluationempirical evaluation

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Research StrategyResearch Strategy

Formal modelsFormal models Integrated perspective on physical and logical mobilityIntegrated perspective on physical and logical mobility Pragmatic use of formal thinkingPragmatic use of formal thinking

• Precise semantics for coordination constructsPrecise semantics for coordination constructs• Formal verification of protocols and algorithmsFormal verification of protocols and algorithms• Informal reasoning during the design processInformal reasoning during the design process

CommunicationCommunication High-level abstract coordination mechanismsHigh-level abstract coordination mechanisms Mobility and location sensitive protocolsMobility and location sensitive protocols

Programming Programming Decoupled style of computingDecoupled style of computing Context aware programming methodsContext aware programming methods Middleware supported application developmentMiddleware supported application development

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Recent ActivitiesRecent Activities

Formal models of mobilityFormal models of mobility• Mobile UNITYMobile UNITY• CodeWeaveCodeWeave

Coordination modelsCoordination models• GVDSGVDS — Global Virtual Data Structures — Global Virtual Data Structures• Application-specific coordination modelsApplication-specific coordination models

Middleware for mobilityMiddleware for mobility• LLIMEIME

• Coordination veneers over Coordination veneers over LLIMEIME

• LLIMEIMELiteLite

Algorithms and protocols for mobile computingAlgorithms and protocols for mobile computing Mobile applications including peer to peer Mobile applications including peer to peer

communication on highwayscommunication on highways

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Mobile UNITYMobile UNITY

ProgramProgram unit of modularityunit of modularity unit of mobilityunit of mobility fully decoupledfully decoupled

MobilityMobility arbitrary physical and logical spacesarbitrary physical and logical spaces reduced to assignmentreduced to assignment

SystemSystem programsprograms small set of coordination constructssmall set of coordination constructs

Proof logicProof logic minimal extension of UNITYminimal extension of UNITY

UNITY + UNITY + + +unique namesunique names

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Model EvaluationModel Evaluation

Rich set of coordination constructs Rich set of coordination constructs expressing transient and transitive expressing transient and transitive interactionsinteractions

Formal specification and Formal specification and verification of Mobile IPverification of Mobile IP

Formal specification and Formal specification and verification of mobile codeverification of mobile code

Semantic basis for a new model of Semantic basis for a new model of fine grained mobility (CodeWeave)fine grained mobility (CodeWeave)

Reactive programming support for Reactive programming support for dynamic reconfigurationdynamic reconfiguration

homeagent

foreignagent

mobilenode

correspondentnode

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Coordination ModelsCoordination Models

Global virtual data Global virtual data structures (GVDS)structures (GVDS)

Service provision (Jini) in Service provision (Jini) in ad hoc networksad hoc networks

Event notification in ad Event notification in ad hoc networkshoc networks

Ad hoc code repositoriesAd hoc code repositories Administrative domain Administrative domain

structures in ad hocstructures in ad hocservice registration

service usage

service discovery

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mobileagent

federated tuple space

hosttuple space

A Middleware for Mobility — LA Middleware for Mobility — LIMEIME

ProfileProfile Linda-style coordination extended to ad Linda-style coordination extended to ad

hoc settingshoc settings Transparent data sharing based on Transparent data sharing based on

connectivityconnectivity Atomic and transitive engagement and Atomic and transitive engagement and

disengagementdisengagement Selective data sharingSelective data sharing Transparent tuple migrationTransparent tuple migration Novel reactive constructsNovel reactive constructs

DistributionDistribution Open sourceOpen source Available on Available on SourceForgeSourceForge

Active effortsActive efforts LLIMEIMELiteLite Coordination veneersCoordination veneers

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Mobile AlgorithmsMobile Algorithms

New algorithm design strategies New algorithm design strategies for nomadic settingsfor nomadic settings

host as message paradigmhost as message paradigm FIFO communication/motionFIFO communication/motion

Message deliveryMessage delivery adaptation of distributed adaptation of distributed

snapshotssnapshots Mobile trackingMobile tracking

based on diffusing computationsbased on diffusing computations Termination detectionTermination detection

formal derivationformal derivation disconnected routingdisconnected routing

mobileunit

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ApplicationsApplications

Wireless chat roomWireless chat room Decoupled game playingDecoupled game playing Commando gamesCommando games Cooperative work (puzzle)Cooperative work (puzzle)

Technology transferTechnology transferFord ResearchFord Research, Detroit, MI, Detroit, MI

smart intersectionssmart intersections synchronized cruse controlsynchronized cruse control

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Context Awareness RevisitedContext Awareness Revisited

Context awareness is a necessity in ad hoc mobilityContext awareness is a necessity in ad hoc mobility Agility is important in highly dynamic environmentsAgility is important in highly dynamic environments Small components rely on opportunistically available Small components rely on opportunistically available

resources while availableresources while available Perception of context varies by task and situationPerception of context varies by task and situation Large-scale deployment of context-aware middleware Large-scale deployment of context-aware middleware

rests with asking for exactly what is needed, when it is rests with asking for exactly what is needed, when it is needed, and nothing more needed, and nothing more

Transparent context management can simplify the Transparent context management can simplify the programming taskprogramming task

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Computational ModelComputational Model

Ad hoc networkAd hoc network Mobile hostMobile host Mobile agentMobile agent Object/DataObject/Data

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Agent-Centered ContextAgent-Centered Context

referenceagent

Context is extended beyond Context is extended beyond host boundarieshost boundaries

Context is separated into Context is separated into task-specific viewstask-specific views

An agent may have An agent may have multiple viewsmultiple views

Views may change Views may change over timeover time

Views are defined in Views are defined in terms of propertiesterms of propertiesof the network, hosts, of the network, hosts, agents, and objectsagents, and objects

Active views may exhibit built-in Active views may exhibit built-in behaviors (e.g., data migration)behaviors (e.g., data migration)

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Technical ConsiderationsTechnical Considerations

Presentation stylePresentation style coordination model amd semanticscoordination model amd semantics

DefinitionDefinition declarative specificationdeclarative specification expressive powerexpressive power

ComputationComputation context discovery and maintenancecontext discovery and maintenance context evaluation infrastructurecontext evaluation infrastructure

Delivery vehicleDelivery vehicle middleware frameworkmiddleware framework

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Perspectives on ContextPerspectives on Context

Context-sensitive data structuresContext-sensitive data structures Context-sensitive referencesContext-sensitive references Context-sensitive bindingsContext-sensitive bindings Context-sensitive eventsContext-sensitive events

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Declarative Context SpecificationDeclarative Context Specification

D = distance to the first D = distance to the first open EXXON gas station open EXXON gas station on the righton the right

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B = Internet access via a B = Internet access via a 1Mb connection within 1Mb connection within two hopstwo hops

P = closest laser printer P = closest laser printer within 50 ft.within 50 ft.

EXXON 9.2 mil.

lpr:john

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Infrastructure SupportInfrastructure Support

Group membershipGroup membership masking unannounced masking unannounced

disconnectiondisconnection location based protocolslocation based protocols safe distance conceptsafe distance concept

Network abstractionNetwork abstraction spatiotemporal servicesspatiotemporal services strictly monotonic metricsstrictly monotonic metrics bounds bounds

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Points of SynergyPoints of Synergy

Executable specificationsExecutable specifications Formal semantic analysisFormal semantic analysis Weak semantics and formal guaranteesWeak semantics and formal guarantees Algorithm and protocol design and analysisAlgorithm and protocol design and analysis Novel routing protocolsNovel routing protocols Security mechanicsSecurity mechanics Common middleware frameworksCommon middleware frameworks

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ConclusionsConclusions

Mobility challenges our way of thinkingMobility challenges our way of thinking we explore novel uses of location information and morewe explore novel uses of location information and more

A solid grounding in traditional distributed computing is a A solid grounding in traditional distributed computing is a prerequisite for successprerequisite for success

we leverage off past work on formal models and algorithmswe leverage off past work on formal models and algorithms

Complexity demands an increasing reliance on Complexity demands an increasing reliance on pragmatic application of rigorous design techniquepragmatic application of rigorous design technique

we focus on coordination models having precise semanticswe focus on coordination models having precise semantics

Sensitivity to the market place and application demands Sensitivity to the market place and application demands is more important than everis more important than ever

we emphasize application-driven empirical evaluationwe emphasize application-driven empirical evaluation

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Thank you …Thank you …

cs.wustl.edu/mobilab/cs.wustl.edu/mobilab/