CPET 565 Mobile Computing Systems Context-Aware Computing Lecture 10 Hongli Luo Indiana University-Purdue University Fort Wayne

Context-Aware Computing Adaptive mobile systems Adaptive mobile systems Application-transparent approachApplication-transparent approach Application-aware approachApplication-aware approach Context-aware computing paradigm Context-aware computing paradigm Context-aware computing Context-aware computing adapting to availability of computing and communication resourcesadapting to availability of computing and communication resources Adapting to context informationAdapting to context information

Context-Aware Computing Context: Context: Enumeration-based (categories)Enumeration-based (categories) Role-based (roles of context in building mobile applications)Role-based (roles of context in building mobile applications) Active context Active context Passive context Passive context

Categories of Context Computing context includes network connectivity, communication costs, communication bandwidth, and local resources, such as printers, displays, and workstations Computing context includes network connectivity, communication costs, communication bandwidth, and local resources, such as printers, displays, and workstations User context includes user profiles, location, and people in the vicinity of the user User context includes user profiles, location, and people in the vicinity of the user Physical context includes lighting and noise levels, traffic conditions, and temperature Physical context includes lighting and noise levels, traffic conditions, and temperature Temporal context includes time of day, week, month, and season of the year Temporal context includes time of day, week, month, and season of the year Context history is the recording of computing, user, and physical context over time Context history is the recording of computing, user, and physical context over time

The 5 W’s… Who is the user? Who are the people with which the user is interacting, or who is nearby? Who is the user? Who are the people with which the user is interacting, or who is nearby? social contextsocial context What is the user doing? What is the user doing? Function contextFunction context Where is the user? Home? Work? Bathroom? Familiar coffee shop? Where is the user? Home? Work? Bathroom? Familiar coffee shop? Location context, the most widely used type of contextLocation context, the most widely used type of context Raw location or higher levelRaw location or higher level When? What time is it? When? What time is it? Temporal contextTemporal context Why? Why is the user performing a certain task? Why? Why is the user performing a certain task? Motivating context, one of the most difficulty type of contextMotivating context, one of the most difficulty type of context Low-level vs. High-level details Low-level vs. High-level details

The 5 W’s… Low-level Low-level Can be sensed directly using sensors or through simple processingCan be sensed directly using sensors or through simple processing E.g., by accessing a database, room temperaturesE.g., by accessing a database, room temperatures High-level details High-level details Involve the amalgamation of low-level context information and sophisticated processingInvolve the amalgamation of low-level context information and sophisticated processing Social situation, activitiesSocial situation, activities

Context Overview

Context-Aware Computing & Apps Context-Aware Computing Devices & Applications - Mobile applications Context-Aware Computing Devices & Applications - Mobile applications User’s context changes frequentlyUser’s context changes frequently Need context-aware behaviorNeed context-aware behavior Capability & Features Capability & Features Proactive in acquiring contextual informationProactive in acquiring contextual information Adapt their response based on the acquired infoAdapt their response based on the acquired info

Context-aware Requirements Contextual sensing Contextual sensing detection of environmental statesdetection of environmental states Contextual adaptation Contextual adaptation capability of the system to adapt its behavior by using contextual informationcapability of the system to adapt its behavior by using contextual information Contextual resource discovery Contextual resource discovery capability to discover available resources in an environmentcapability to discover available resources in an environment Contextual augmentation Contextual augmentation capability to associate contextual information with some digital datacapability to associate contextual information with some digital data Example: association of a particular meeting place and attendees with a set of minutesExample: association of a particular meeting place and attendees with a set of minutes Example: association of a digital photo with a specific locationExample: association of a digital photo with a specific location

Types of Context-Aware Apps Types of Context Awareness Applications Types of Context Awareness Applications Function or Service TypeFunction or Service Type Providing information Providing information Actuating commands Actuating commands InitiationInitiation Explicitly by the user (manual) Explicitly by the user (manual) Invoked implicitly by the application (auto) Invoked implicitly by the application (auto) Adaptation (contextual selection)Adaptation (contextual selection) Information Information System System User Interface User Interface Command (behavior): IF-THEN rules Command (behavior): IF-THEN rules

Context-Aware Computing & Apps Developing Context-Aware Applications Developing Context-Aware Applications 1.Identifying relevant context – application dependent 2.Specifying context-ware behaviors: considering reuse 3.Integrating with mechanisms for acquisition of contextual information – platform dependent

Context-Aware Computing & Apps (cont.) Specifying Context-aware Behaviors Specifying Context-aware Behaviors ReuseReuse Two Example ApproachesTwo Example Approaches Context-triggered actions Context-triggered actions Stick-E notes Stick-E notes

Context-Aware Computing & Apps (cont.) Specifying Context-aware Behaviors Specifying Context-aware Behaviors Context-triggered actionsContext-triggered actions Active Badge Location System Active Badge Location System Watchdog and contextual reminder for active badges Watchdog and contextual reminder for active badges System configuration files – parameters, (location, action) in the format: System configuration files – parameters, (location, action) in the format: Badge location event-type actionBadge location event-type action Watchdog Monitoring Events – invoke Actions: Watchdog Monitoring Events – invoke Actions: ArrivingArriving DepartingDeparting Settle-InSettle-In MissingMissing AttentionAttention

Context-Aware Computing & Apps (cont.) Specifying Context-aware Behaviors Specifying Context-aware Behaviors Stick-E Note (Brown, 1995; Pascoe, 1997) motivated by Post-It noteStick-E Note (Brown, 1995; Pascoe, 1997) motivated by Post-It note Supporting platformSupporting platform For PDA with wireless connectivity to a communication network For PDA with wireless connectivity to a communication network Equipped with various sensor: GPS, etc Equipped with various sensor: GPS, etc Major componentsMajor components Context Context Location, nearby users, time (where, who, when)Location, nearby users, time (where, who, when) Content Content InformationInformation ActionsActions InterfacesInterfaces

Context-Aware Computing & Apps (cont.) Stick-E Note (Brown, 1995; Pascoe, 1997) Stick-E Note (Brown, 1995; Pascoe, 1997) Position sensingPosition sensing Active badge system Active badge system GPS GPS Beacons, cell phones, bar-codes scanners Beacons, cell phones, bar-codes scanners Standard Generalized Markup Language (SGML)Standard Generalized Markup Language (SGML) tag tag