1. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel1 Context Evidence and Location Authority the disciplined management of sensor data into context models Chris Johnson (Australian National Univ) David Carmichael, Judy Kay, Bob Kummerfeld (Univ of Sydney) René Hexel (Griffith Univ) Smart Internet Technology Cooperative Research Centre Australia

2. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel2 Context evidence & location authority Key problems: digest high data rate raw sensor data to manageable input for smart applications capture and reuse models, software and system designs and components for further applications

3. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel3 Context Service Layers are not hard-bordered Sensor aggregation, context, and rich context are seen as a continuum Context layers and smart applications have access to the IE Repository Repository contains models and also numbers of evidence accumulators Accretion+resolution: smarter sensors apply resolution procedures to one or more sets of accumulated evidence, on request

4. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel4 Location modelling: focus and fusion focus: “location” is too big to model in all its aspects that we know about but fusion/reuse: location models are expensive, we need to be able to combine existing models for new apps

5. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel5 Articulated location models a location authority is a common base model for many applications: –a coordinate system, or naming, or landmarks –basic location data mapping relations e.g. room/zone names, contains relation, sensor-location map –maintenance procedures to continue models’ correspondence with changing reality location context services are differentiated for applications –e.g. where am I? where is person F? what printer devices are near location P?

6. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel6 Reusing models Effective reuse of implemented context- awareness models needs more than a software library common software systems architecture: layering discipline management of designed use of similar components across layer boundaries –software components: support layers and prototypes –system design notations

7. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel7

8. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel8 Context evidence: summary Reuse sensors and components: resolve evidence diffferently for different applications Design diagrams help to manage complexity of constructing with varying evidence streams

9. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel9 (last slide)

10. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel10 Discipline and reuse revealing the design exposes system quality issues to scrutiny: –e.g. trust and privacy of the user models and the sensor data flows articulating the location authority/context service allows differentiation between applications, while reusing common models focussed design notations encourage reuse through understanding and design review scrutiny

11. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel11 Reuse in development of IE systems reuse of sensors, smart environment agents, information models, location authority models for environment (and authority’s contents and maintenance) specialisation to application functional and quality needs such as scale of distribution, specific location context information services, user privacy/trust. Architectures and design methods, not just libraries.

12. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel12 Identity and User Profiles The IER and user profile/model database overlap considerably: eg location is an attribute of a person –should we merge them? use the same access method/API? Identity: –more than session authentication and single signon –authentication + user profile/model

13. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel13 Context producers and consumers Context producer: –A simple sensor –A complex rich context generator Context consumer: –A program that uses context information in its operation –Consumers can also be producers: rich context

14. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel14 IE Usage Scenario (technical, not user level scenario) Sensors find a local IE repository server using DNS SRV records (several servers may live in a cloud to share load) A sensor detects a device and determines its unique ID (MAC address etc) The sensor notifies its local IER of the event The IER uses the URN->URI resolution to find the home IER for the device and sends an update to the home IER Programs (context, SPA etc) that have registered for notifications when the device is detected will be notified

15. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel15 (5) Sensors and messaging Sensors are just above the level of dumb sensors – they are connected to the net and can use standard protocols IE repositories communicate –with sensors using logical multicast –with other IE repositories using peer-to- peer services

16. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel16 (6) Intelligent Environment Repository the Repository is in essence a distributed structured object database access to objects is via views views provide mechanisms for privacy views allow personas to be defined as models over identity

17. 2004-09-07Johnson Carmichael Kay Kummerfeld Hexel17 smart applications SEA context sensor aggregation device abstraction devices User model Intelligent Env Repository Context Service Layers sensors smart environment agents