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

2. 2 MOBILE COMPUTING MOBILE COMPUTING

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21. 21 Trends in Mobile Computing Technology Technology Miniaturization Miniaturization Wireless communication Wireless communication Java Java Society Society Ubiquitous access Ubiquitous access Increasing levels of mobility Increasing levels of mobility Computing and communication melting into the fabric of society Computing and communication melting into the fabric of society InfrastructureInfrastructure EnterprisesEnterprises PeoplePeople

22. 22 Physical Mobility Fixed network Fixed network Nomadic computing Nomadic computing Ad hoc computing Ad hoc computing

23. 23 Research Implications New design constraints New design constraints Frequent disconnection Frequent disconnection Unpredictable movement Unpredictable movement Asymmetric bandwidth Asymmetric bandwidth Limited resources Limited resources Short battery life Short battery life Interesting opportunities Interesting opportunities Spatial knowledge Movement profile Increased demands Increased demands Reasoning about behavior Connectivity maintenance Adaptation

24. 24 Logical Mobility Code on demand Code on demand Remote evaluation Remote evaluation Mobile agents Mobile agents

25. 25 Research Trends Code on demand is made popular by Java Code on demand is made popular by Java Mobile code languages (e.g., Oblique, Facile, Telescript) are losing ground Mobile code languages (e.g., Oblique, Facile, Telescript) are losing ground Mobile agent systems (e.g., Agent TCL) are an emerging new technology Mobile agent systems (e.g., Agent TCL) are an emerging new technology Middleware is growing in practical importance Middleware is growing in practical importance

26. 26 Mobility Paradigms Continued access to remote resources Continued access to remote resources Delegation to mobile agents Delegation to mobile agents Disconnected operation Disconnected operation Ad hoc grouping of people and devices Ad hoc grouping of people and devices Mass mobility Mass mobility

27. 27 Ad Hoc Network Challenge No fixed network infrastructure No fixed network infrastructure Transient interactions Transient interactions Decoupled computing Decoupled computing Open environment Open environment Physical and logical mobility Physical and logical mobility Frequent disconnections Frequent disconnections Limited guarantees Limited guarantees

28. 28 Sample Applications Highway information management Highway information management Disaster response Disaster response Military applications Military applications Contamination zone exploration Contamination zone exploration Wireless anywhere classroom Wireless anywhere classroom Cave and mine exploration Cave and mine exploration Self-organizing office and factory Self-organizing office and factory Video games in physical spaces Video games in physical spaces

29. 29 Mobile Computing Laboratory Rapid development of dependable mobile applications over ad hoc networks Formal models: Formal models: precise semantics and analysisprecise semantics and analysis Coordination Models Coordination Models rapid developmentrapid development Middleware: Middleware: easy disseminationeasy dissemination Algorithms: Algorithms: feasible implementationfeasible implementation Applications: Applications: empirical evaluationempirical evaluation

30. 30 Research Strategy Formal models Formal models Integrated perspective on physical and logical mobility Integrated perspective on physical and logical mobility Pragmatic use of formal thinking Pragmatic 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 Communication Communication High-level abstract coordination mechanisms High-level abstract coordination mechanisms Mobility and location sensitive protocols Mobility and location sensitive protocols Programming Programming Decoupled style of computing Decoupled style of computing Context aware programming methods Context aware programming methods Middleware supported application development Middleware supported application development

31. 31 Recent Activities Formal models of mobility Formal models of mobility Mobile UNITYMobile UNITY CodeWeaveCodeWeave Coordination models Coordination models GVDS Global Virtual Data StructuresGVDS Global Virtual Data Structures Application-specific coordination modelsApplication-specific coordination models Middleware for mobility Middleware for mobility L IMEL IME Coordination veneers over L IMECoordination veneers over L IME L IME LiteL IME Lite Algorithms and protocols for mobile computing Algorithms and protocols for mobile computing Mobile applications including peer to peer communication on highways Mobile applications including peer to peer communication on highways

32. 32 Mobile UNITY Program Program unit of modularity unit of modularity unit of mobility unit of mobility fully decoupled fully decoupled Mobility Mobility arbitrary physical and logical spaces arbitrary physical and logical spaces reduced to assignment reduced to assignment System System programs programs small set of coordination constructs small set of coordination constructs Proof logic Proof logic minimal extension of UNITY minimal extension of UNITY UNITY + + unique names X Y

33. 33 Model Evaluation Rich set of coordination constructs expressing transient and transitive interactions Rich set of coordination constructs expressing transient and transitive interactions Formal specification and verification of Mobile IP Formal specification and verification of Mobile IP Formal specification and verification of mobile code Formal specification and verification of mobile code Semantic basis for a new model of fine grained mobility (CodeWeave) Semantic basis for a new model of fine grained mobility (CodeWeave) Reactive programming support for dynamic reconfiguration Reactive programming support for dynamic reconfiguration home agent foreign agent mobile node correspondent node

34. 34 Coordination Models Global virtual data structures (GVDS) Global virtual data structures (GVDS) Service provision (Jini) in ad hoc networks Service provision (Jini) in ad hoc networks Event notification in ad hoc networks Event notification in ad hoc networks Ad hoc code repositories Ad hoc code repositories Administrative domain structures in ad hoc Administrative domain structures in ad hoc service registration service usage service discovery

35. 35 mobile agent federated tuple space host tuple space A Middleware for Mobility L IME Profile Profile Linda-style coordination extended to ad hoc settings Linda-style coordination extended to ad hoc settings Transparent data sharing based on connectivity Transparent data sharing based on connectivity Atomic and transitive engagement and disengagement Atomic and transitive engagement and disengagement Selective data sharing Selective data sharing Transparent tuple migration Transparent tuple migration Novel reactive constructs Novel reactive constructs Distribution Distribution Open source Open source Available on SourceForge Available on SourceForge Active efforts Active efforts L IME Lite L IME Lite Coordination veneers Coordination veneers

36. 36 Mobile Algorithms New algorithm design strategies for nomadic settings New algorithm design strategies for nomadic settings host as message paradigm host as message paradigm FIFO communication/motion FIFO communication/motion Message delivery Message delivery adaptation of distributed snapshots adaptation of distributed snapshots Mobile tracking Mobile tracking based on diffusing computations based on diffusing computations Termination detection Termination detection formal derivation formal derivation disconnected routing disconnected routing mobile unit

37. 37 Applications Wireless chat room Wireless chat room Decoupled game playing Decoupled game playing Commando games Commando games Cooperative work (puzzle) Cooperative work (puzzle) Technology transfer Ford Research, Detroit, MI Technology transfer Ford Research, Detroit, MI smart intersections smart intersections synchronized cruse control synchronized cruse control

38. 38 Context Awareness Revisited Context awareness is a necessity in ad hoc mobility Context awareness is a necessity in ad hoc mobility Agility is important in highly dynamic environments Agility is important in highly dynamic environments Small components rely on opportunistically available resources while available Small components rely on opportunistically available resources while available Perception of context varies by task and situation Perception of context varies by task and situation Large-scale deployment of context-aware middleware rests with asking for exactly what is needed, when it is needed, and nothing more Large-scale deployment of context-aware middleware rests with asking for exactly what is needed, when it is needed, and nothing more Transparent context management can simplify the programming task Transparent context management can simplify the programming task

39. 39 Computational Model Ad hoc network Ad hoc network Mobile host Mobile host Mobile agent Mobile agent Object/Data Object/Data

40. 40 Agent-Centered Context reference agent Context is extended beyond host boundaries Context is extended beyond host boundaries Context is separated into task-specific views Context is separated into task-specific views An agent may have multiple views An agent may have multiple views Views may change over time Views may change over time Views are defined in terms of properties of the network, hosts, agents, and objects Views are defined in terms of properties of the network, hosts, agents, and objects Active views may exhibit built-in behaviors (e.g., data migration) Active views may exhibit built-in behaviors (e.g., data migration)

41. 41 Technical Considerations Presentation style Presentation style coordination model amd semantics coordination model amd semantics Definition Definition declarative specification declarative specification expressive power expressive power Computation Computation context discovery and maintenance context discovery and maintenance context evaluation infrastructure context evaluation infrastructure Delivery vehicle Delivery vehicle middleware framework middleware framework

42. 42 Perspectives on Context Context-sensitive data structures Context-sensitive data structures Context-sensitive references Context-sensitive references Context-sensitive bindings Context-sensitive bindings Context-sensitive events Context-sensitive events

43. 43 Declarative Context Specification D = distance to the first open EXXON gas station on the right D = distance to the first open EXXON gas station on the right … B = Internet access via a 1Mb connection within two hops B = Internet access via a 1Mb connection within two hops P = closest laser printer within 50 ft. P = closest laser printer within 50 ft. EXXON 9.2 mil. lpr:john

44. 44 Infrastructure Support Group membership Group membership masking unannounced disconnection masking unannounced disconnection location based protocols location based protocols safe distance concept safe distance concept Network abstraction Network abstraction spatiotemporal services spatiotemporal services strictly monotonic metrics strictly monotonic metrics bounds bounds

45. 45 Points of Synergy Executable specifications Executable specifications Formal semantic analysis Formal semantic analysis Weak semantics and formal guarantees Weak semantics and formal guarantees Algorithm and protocol design and analysis Algorithm and protocol design and analysis Novel routing protocols Novel routing protocols Security mechanics Security mechanics Common middleware frameworks Common middleware frameworks

46. 46 Conclusions Mobility challenges our way of thinking Mobility challenges our way of thinking we explore novel uses of location information and more we explore novel uses of location information and more A solid grounding in traditional distributed computing is a prerequisite for success A solid grounding in traditional distributed computing is a prerequisite for success we leverage off past work on formal models and algorithms we leverage off past work on formal models and algorithms Complexity demands an increasing reliance on pragmatic application of rigorous design technique Complexity demands an increasing reliance on pragmatic application of rigorous design technique we focus on coordination models having precise semantics we focus on coordination models having precise semantics Sensitivity to the market place and application demands is more important than ever Sensitivity to the market place and application demands is more important than ever we emphasize application-driven empirical evaluation we emphasize application-driven empirical evaluation

47. 47 Thank you … cs.wustl.edu/mobilab/