A Study of Context-Awareness: The Context Toolkit, CORTEX Presented by Babar Tareen IDS Lab., Seoul National University The Context Toolkit: Aiding the Development of Context-Aware Applications (2000) Anind K. Dey and Gregory D. Abowd Graphics, Visualization and Usability Center, Georgia Institute of Technology Atlanta, USA The Context Toolkit: Aiding the Development of Cont ext-Enabled Applications (1999) Daniel Salber, Anind K. Dey and Gregory D. Abowd Graphics, Visualization and Usability Center, Georgia Institute of Technology Atlanta, USA Context-Aware Middleware for Pervasive and Ad Hoc Environment Hector A. Duran-Limon, Gordon S. Blair, Adrian Friday, Paul Grace, George Samartzidis, Thirunavukkarasu Sivaharan, Maomao WU Computing Department, Lancaster University, Lancaster UK ects/cortex/publications.htm

Copyright  2008 by CEBT Part I. The Context Toolkit  Related publications [Last publication in 2002] 1.Stuck in the Middle: The Challenges of User-Centered Design and Evaluation for Middleware 2.Distributed Mediation of Ambiguous Context in Aware Environments 3.Stuck in the Middle: Bridging the Gap Between Design, Evaluation, and Middleware 4.A Conceptual Framework and a Toolkit for Supporting the Rapid Prototyping of Context-Aware Applications 5.The Family Intercom: Developing a Context-Aware Audio Communication System 6.Understanding and Using Context 7.Providing Architectural Support for Building Context-Aware Applications 8.Distributed and Disappearing User Interfaces in Ubiquitous Computing 9.Distributed Mediation of Imperfectly Sensed Context in Aware Environments 10.CybreMinder: A Context-Aware System for Supporting Reminders 11.The Context Toolkit: Aiding the Development of Context-Aware Applications 12.Enabling the Use of Context in Interactive Applications 13.The What, Who, Where, When and How of Context-Awareness 14.Proceedings of the CHI 2000 Workshop on "The What, Who, Where, When and How of Context Awareness 15.Towards a Better Understanding of Context and Context-Awareness 16.The Conference Assistant: Combining Context-Awareness with Wearable Computing 17.A Context-based Infrastructure for Smart Environments 18.An Architecture To Support Context-Aware Applications 19.Towards a Better Understanding of Context and Context-Awareness 20.The Context Toolkit: Aiding the Development of Context-Enabled Applications 21.Designing for Ubiquitous Computing: A Case Study in Context Sensing 22.The Design and Use of a Generic Context Server 2

Copyright  2008 by CEBT Introduction  Context covers information that is part of an application’s opera ting environment and that can be sensed by the application  Issues: Nature of the context information makes the difficulties in using context. 1.It is acquired from unconventional sensors. – For Ex: Location can be sensed by GPS, Active Badge devices, floor emb edded presence sensors or video image processing 2.It must be abstracted to make sense for the application. – GPS coordinates vs. Street number or Building name 3.It may be acquired from multiple distributed and heterogeneous sources. 4.It is dynamic 3

Copyright  2008 by CEBT Context Toolkit - Design  Aim is to develop reusable solution to make development of context aware applications easier  Inspired by the success of GUI development kits  GUI Toolkits Hide underlying complexity Manage the details of interaction Provide reusable building blocks 4

Copyright  2008 by CEBT Widget  An object used to hold data and present an interface to the user. A widget is a combination of state and procedure. 5

Copyright  2008 by CEBT Context Toolkit - Components 6  Widgets [Context Widget] Widgets acts between user and environment Encapsulate information about a single piece of context – Location, Activity etc Support traditional poll and subscription mechanisms Hide the complexity of actual sensors used from application Abstract context information to suit the expected needs Provide reusable building blocks for context sensing  Aggregators Like Meta-Widgets Aggregate context information Hide even more complexity about the context  Interpreters Used to abstract or interpret low-level context information

Copyright  2008 by CEBT Implementation Details  Distribution Applications can access context from distributed widgets Widget context from distributed generators – A generator acquires raw context information from sensors  Composition  Communicating Across Heterogeneous Components HTTP/XML based communication model  Handling Dynamism Polling / Subscription  Resource Discovery [Future Work]  Implemented in Java  Source available at [December 30, 2003] 7

Copyright  2008 by CEBT Examples of Context Widgets  IdentityPresence widget  Activity Widget  NamePresence widget  PhoneUse widget  MachineUse widget 8

Copyright  2008 by CEBT Applications  In/Out Board Electronic equivalent of a simple in/out board  Information Display displays information relevant to the user’s location and identity on a display adjac ent to the user  DUMMBO Meeting Board an instrumented digitizing whiteboard that supports the capture and access of inf ormal and spontaneous meetings  Context-aware mailing list only sends an incoming to those people who are currently in the building  Conference Assistant aids users when attending a conference  CybreMinder a context-aware system that supports the creation, delivery, and handling of rem inders 9

Copyright  2008 by CEBT Review  Pros Complete implementation is available Multiple applications are built using Context Toolkit  Cons The concept of Context Widgets is another name for Encapsulation Unlike GUI Widgets which are mostly independent, Context widgets depend on sensors. We need to adjust widgets for different sensors There is no common model to represent context information, that is, application developer have to define what the context is and how to represent it [Not defined in the paper] 10

Copyright  2008 by CEBT Part II. Context-Aware Middleware for Pervasive and Ad Hoc Environments  Related Publications [Last publication in 2004] Novel Component Middleware for Building Dependable Sentient Computing Applications Cooperating Sentient Vehicles for Next Generation Automobiles Context-Aware Middleware for Pervasive and Ad Hoc Environments Harnessing Context to Support Proactive Behaviours Exploiting User Models and Context-Awareness to Support Personal Daily Activities Developing a Context Sensitive Tourist Guide Using and Determining Location in a Context-Sensitive Tour Guide The Role of Connectivity in Supporting Context-Sensitive Applications Developing Context-Aware Electronic Tourist Guide Experiences of Developing and Deploying a Context-Aware Tourist Guide Providing Tailored (Context-Aware) Information to City Visitors Developing a Context Sensitive Tourist Guide  Mostly related to travel guide scenario 11

Copyright  2008 by CEBT Introduction  CORTEX: CO-operating Real-time senTient objects  Objective: construction of applications out of proactive, mobile, c ontext-aware entities termed as sentient objects.  Sensor: is an entity that produces software events in reaction to a event detected by some real-world hardware device  Actuators: is an entity which consumes software events, and re acts by attempting to change the state of the real world in some way via some hardware device  Sentient object: is an entity that can both consume and produc e software events 12

Copyright  2008 by CEBT Context  Context: Any information sensed from the environment, which m ay be used to describe the current situation of a sentient object  Context Aware: A context-aware application is an application wh ose behavior is controlled by its context, to some degree. 13

Copyright  2008 by CEBT Sentient Object  Sentient objects are objects that receive events as input, process them and generate further events as output 14

Copyright  2008 by CEBT CORTEX Middleware  Structured as number of component frameworks (CF)  Developed in OpenCOM 15

Copyright  2008 by CEBT Publish / Subscriber CF 16  The role of the publisher component is to push events to the event syste m whereas the subscriber component receives events.  Users get notified of the arrival of an event by the notify component  Support for subject-, content- and context-based event filtering  Uses XML to represent events  Dissemination of events over the network is achieved by SOAP Interface: a unit of service provision Receptacle: a unit of service requirement

Copyright  2008 by CEBT Service Discovery CF  principal function is to allow services that have been advertised b y different service discovery protocols to be discovered  Supports SLP and UPnP  The service discovery framework presents its own custom interfa ce 17

Copyright  2008 by CEBT Resource Management CF  Passive resource components represent non-processing resources such as system memory and battery life  Jobs are capable of performing some activity, that is, they receive mess ages and process them  Passive resources and jobs are created by factories  Passive resources are managed by managers  Jobs are managed by schedulers 18

Copyright  2008 by CEBT Review  Ambiguities How sentient objects interact with Framework? How different CFs communicate with each other?  Pros Concept of sentient object is new and interesting  Cons Complicated design Publish/Subscribe communication model is used by CORBA, TIBCO, SIENA, Gryphon, JEDI, etc No are provided about Context CF 19

Copyright  2008 by CEBT Context Toolkit & CORTEX  Context Toolkit Objective is to make development of Context Aware applications easier Simple design Many applications are built using Context Toolkit  Confab provides an architecture for privacy-sensitive systems Objective to provide a complete middleware for Pervasive and Ad Hoc Environments Complex Design 20