Part I Surveys of Context-aware Systems

1. Part I Surveys of Context-aware Systems 2008.01.28 임영희 http://idb.korea.ac.kr DB & Mining Lab. Korea University

2. Contents • Definition of Context & Context-aware Application • Architecture of Context-aware System • Context Models • Existent Context-aware Applications • Office and Meeting Tools • Tourist Guide • Memory Aids • Context-aware Home • Essential Technologies for Context-aware Services

3. Definition of Context • Context is • situational information • any information that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and application themselves. • the set of environmental states and settings that either determines an application’s behavior or in which an application event occurs

4. Categories of Context(1) • Categories of Context • Primary context : • Location (where) • Identity (who) • Time (when) • Activity (what) • Secondary context • can be indexed by primary context • Ex) given a person’s identity,  phone number, addresses, birthdate given an entity’s location,  what object are near, what activity is occurring near the entity

5. Categories of Context(2) • Another categories of Context • external (physical) context : • can be measured by h/w sensors • location, light, sound, movement, touch, temperature… • internal (logical) context: • be specified by users or captured monitoring the user’s interaction • user’s goal, tasks, user’s emotional state…

6. Context-aware Application • Definition of Context-Aware • A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on the user’s task • Characteristics of Context-Aware application • presentation of information and services to a user • automaticexecution of a service • tagging of context to information for later retrieval

7. Context-aware Application • Categories of Context-Aware applications • Active context awareness: • An application automatically adapts to discovered context, by changing the application behavior. • Passive context awareness: • An application presents the new or updated context to an interested user or makes the context persistent for the user to retrieve later

8. Architecture of Context-aware Systems • Different approaches context-aware systems • Direct sensor access: • the client s/w gathers the desired information directly form these sensor without layer for gaining and processing sensor data • drivers for the sensor are hardwired into the application • law extensibility, impossibility of managing multiple concurrent sensor access • Middleware based: • a layered architecture with the intention of hiding low-level sensing details • high extensibility • Context Server • middleware base architecture + distributed approach • gathering sensor data  context server

9. application storage/management preprocessing raw data retrieval sensor Abstract Architecture(1) • Sensor • sensing hardware + every data source which provide usable context information • Categories of Sensor • Physical sensors • Virtual sensors : sourcing context data from s/w • Logical sensors : combining physical sensor + virtual sensor

10. application storage/management preprocessing raw data retrieval sensor Abstract Architecture(2) • raw data retrieval • raw data retrieval by using appropriate drivers for physical sensor and APIs for virtual and logical sensors • preprocessing • reasoning and interpreting (transforming) • aggregating of raw context data • solving of sensing conflicts

11. application storage/management preprocessing raw data retrieval sensor Abstract Architecture(3) • storage/management • storing context history • application • implementing actual reaction on different events and context-instances

12. Existent Context-aware Applications • Categories of Context-aware Applications • Office and Meeting Tools • Tourist Guide • Memory Aids • Context-aware Home

13. Office and Meeting Tools(1) • The Active Badge System(1992) • Group: Olivetti Research Ltd. • the first context-aware applications. • persons with badges that transmitted IR-signal • after sensing a location of a person, forwarding calls to the closest phone

14. ParcTab terminal Office and Meeting Tools(2) • The ParcTab System • Group: Xerox Palo Alto Research Center • ParcTab: small wireless palm-sized computer • presenting information about the room the user was in • helping the user find the most convenient local resource, e.g. the nearest printer • Locating other person with ParcTab  Displaying the location information on Active map

15. Office and Meeting Tools • Gaia • Group : Dept. of CS, University of Illinois • extending typical operating system concepts to include context, location awareness, mobile computing devices and actuators like door locks and light switches

16. Tourist Guides • GUIDE • Group: Lancaster University(96~99) • terminal: Fujitsu Teampad 7600 portable PC • supporting Lancaster city visitor • screenshot of GUIDE

17. Memory Aids(1) • Forget-Me-Not • Group: Rank Xerox Research Center • PDA system that records where its user is, who they are with, whom they phone, and other autobiographical information and store it in a DB for later query • terminal: ParcTab

18. Memory Aids(2) • StartleCam • Group: MIT Media Lab. • wearable computer (with digital camera, digital modem) + skin conductivity sensor

19. Context-aware Homes(1) • EasyLiving • Group: Vision Group at Microsoft Research • computer vision for person-tracking and visual user interaction. • multiple sensor modalities combined. • use of a geometric model of the world to provide context. • automatic or semi-automatic sensor calibration and model building. • fine-grained events and adaptation of the user interface. • device-independent communication and data protocols.

20. 상황 인식 서비스 요소 기술(1) • 상황 인식 서비스 요소기술들 • 상황정보 감지 기술 (context sensing) • 상황정보의 변화 감지 기술(context change sensing) • 상황정보 모델링 기술(context modeling) • 상황정보 융합 및 추론 기술(context fusion & reasoning) • 상황정보 교환 기술(context exchange) • 상황정보 툴킷 기술(context toolkit) • 상황인식 서비스 묘사 및 발견 기술(context-aware service description language) • 상항인식 서비스 구조 기술(context-aware service infrastructure)

21. 상황인식 서비스 요소 기술(2) • 상황정보 감지 기술 • 상황정보 수집 경로: • 사용자 인터페이스, 센서, 센서 네트워크 • 위치 인식 시스템의 분류 • 매크로 위치인식 시스템– 광역 위치 인식 시스템(주로 GPS 사용) • 마이크로 위치인식 시스템 • 실내나 지하, 건물 밀집 지역의 위치 인식 제공 • 적외선 기반, 초음파 기반, 무선랜 기반, 영상 기반 시스템 • Ad hoc 위치인식 시스템 • 위치인식을 위한 추가적인 h/w 도입이 어려운 환경에서 사용 • 위치정보를 가지는 레퍼런스 노드와의 무선 링크 연결성만으로 위치를 계산

22. 상황인식 서비스 요소 기술(3) • 상황정보의 변화 감지기술 • 상황정보의 변화 주기에 따라 주기적인 polling이나 상황정보가 특정조건을 만족할 경우에만 reporting • 상황정보 모델링 기술 • 상황정보 융합 및 추론 기술 • 상황정보 융합을 위한 계층적 모델링 요구 • 지능적인 추론이나 확률적인 메커니즘이 도입 • 상황정보 교환기술 • application 간의 복잡한 자료구조를 교환하기 위한 통신 매커니즘 개발이 요구됨 • 상황정보 툴킷 기술 • 코딩부담을 줄여주는 비주얼 프로그래밍 툴이 요구됨

23. 상황인식 서비스 요소 기술(4) • 상황인식 서비스 묘사 및 발견 기술 • 상황인식 서비스 묘사 언어 개발  WSDL등이 사용 • 서비스 발견 기술  에이전트 기술이 주로 활용 • 상황인식 서비스 구조 기술 • 센서, 네트워크, 서비스, 장치 등에 독립적인 infrastructure 개발이 요구됨

24. Part IIContext-Aware Artifacts:Two Development Approaches http://idb.korea.ac.kr DB & Mining Lab. Korea University

25. Introduction • Two development approaches for CA • Self-supported context awareness • designers build the ability to perceive context, reason with it, and act accordingly into the device or its dedicated hardware support. • Infrastructure-supported context awareness • designers obtain context aware capabilities by harnessing a hardware and software infrastructure external to and associated with the device’s space.

26. Context-aware mobile phones (1) • SenSay • context-aware mobile phone that modifies its behavior based on its user's state and surroundings • uses a combination of sensors, including a voice microphone, an ambient-noise microphone, accelerometers, and a light sensor.

27. Context-aware mobile phones (2) • uses a finite-state machine to track the phone’s internal states (uninterruptible, high activity, normal, and idle) • automatically controls ringer and vibration levels, send short-message-service messages to callers, suggest calls to make • provides access to the user’s electronic calendar • Architecture of Sensay

28. Context-aware mobile phones (3) • TEA-II (Technology for Enabling Awareness) • self-contained hardware device that plugs into mobile phones to add context-aware capabilities • The plug-in’s sensors: two light sensor, two microphones, a dual axis accelerometer, a digital temperature sensor and a touch sensor. • detects phone situations( in hand, on table, in pocket, and outdoors) • explores an exchange of context information between caller and callee. • adds a delay of up to 30 seconds. • Doesn’t consider internal phone state and action decision making

29. Other context-aware objects (1) • Sensor-Doll • emits different sounds and music according to its situation and how users handle it • Spoons and cups • Mediacup • MIT’s Chameleon Mug • MIT’s Intelligent Spoon

30. Other context-aware objects (2) • Funiture • Chameleon Table • Smart Couch • Medication dispensers • Context-aware pill bottle

31. Other context-aware objects (3) • Cameras • Context photography: • uses sound and movement as context information and a set of custom-made computer graphics effects which affect images in real time • Example of context pictures

32. Discussion • Advantages of self-supported CA • By equipping objects with sensors, we can gain otherwise unavailable information about the object’s situation • Reduced dependency on external infrastructure • Challenges of self-supported CA • embedding sensors unobtrusively • reasoning with the context efficiently and accurately given limited computational resources • enabling appropriate actions

33. Infrastructure-supported CA (1) • Infrastructure for CA • acts as a mechanism for detecting, combining, and reasoning with different objects’ disparate context information • should not only consist of an architecture to represent objects and events, but also provide various services • a well-established, pervasive, reliable, and publicly accessible set of technologies that act as a foundation for other systems The relationship between CA artifacts and the context-awareness infrastructure

34. Infrastructure-supported CA (2) • Weather-aware clothes hanger • hangers light up according to the day’s forecast • RFID Chef prototype • Detects RFID-tagged grocery items on a kitchen counter • Display a list of recipes using these items as ingredients

35. Infrastructure-supported CA (3) • Benefits of infrastructure support • hardware, platform, and language independence • ease of maintenance, in that administrators can change infrastructure-linked services, sensors, and artifacts while the system is running • improved context awareness economics • Users can update infrastructures and add new artifacts to an existing environment • can support complex context-awareness behavior

36. Conclusion • Considerations for CA Developers • How can a system best acquire context? • Should we choose a self-supported or infrastructure-based approach (or some combination)? • How can the system reason with and use context for a particular application given the constraints of cost, reasoning efficiency, timeliness of action, and user intelligibility? • How can we program such entities to respond appropriately to richer contextual information? • How will users perceive automatic responses from artifacts and devices?