1. Context Infrastructure for Developing Context-Aware Applications Fakultät Informatik, Institut für Systemarchitektur, Lehrstühl für Rechnernetze Jordan Janeiro jordan.janeiro@tu-dresden.de CRUISe Project

2. 2 von 15 Agenda Why Develop Context-Aware Applications MoCA Framework –Architecture –Context Model Use Cases - CRUISe

3. 3 von 15 Motivation Ubiquitous and Pervasive computing demonstrate a trend towards more complex and dynamic computer networks This complexity is mainly introduced by: –Varying quality of wireless links; –Heterogeneous capabilities of connected nodes; –QoS and reliability Adaptation of services by “context” changes –Dynamically; –Transparently

4. 4 von 15 Motivation Context is … –” Context is any information that can be used to characterise 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 applications themselves.” Adaptations need support of a software infrastructure to provide context –Implement the retrieval of “low-level” information in the mobile devices –Many middlewares were proposed

5. 5 von 15 Objectives Use a software infrastructure to support the retrieval of context information –Implemented as “sensors” Bandwidth Location Luminosity Implement adaptation rules based on the context information

6. 6 von 15 Mobile Collaboration Architecture - MoCA

7. 7 von 15 Mobile Collaboration Architecture - MoCA Discovery Service –Accepts announcements of applications, and allows Clients to locate the corresponding Servers and Proxies; Configuration Service –Stores and manages the configuration of each mobile device: MAC Address, (IP:port) pair of CIS, periodicity of the Monitor repots to the CIS, and (IP:port) pair of the Discovery Service; Location Inference Service –Infer the location of devices using 802.11 interface (indoors) Context Information Service –Stores and processes the state information received from the Monitors, and eventually sends notifications about context changes to Proxies which have subscribed to such notifications Monitor –Is in charge of: (i) probing the state information (aka execution context) of the mobile device and (ii) sending this information to the Context Information Service (CIS) executing in the static network

8. 8 von 15 Mobile Collaboration Architecture - Monitor Is a daemon executing on the mobile device; –Periodically polls (and sends to the CIS) state information about the mobile device’s resources and wireless RF signals, e.g.: Strength of RF signal received from all visible Access Points ; CPU utilization, available memory and energy; MAC Address, IP and currently used Access Point; RF signals are obtained through WiFi scan operations independently of the 802.11 network interface; Also reports to the CIS any change of the current IP address or Access Point of the device (i.e. a migration) Implementations ready for –Windows XP –Windows CE –Linux –Symbian –Nokia N60

9. 9 von 15 Mobile Collaboration Architecture - Monitor

10. 10 von 15 Mobile Collaboration Architecture – Monitor Simulator Is a tool which simulates a mobile device: –Behavior defined by a configuration file (scans are read from different files) –Sends this information to CIS (like the “real” Monitor) –Can be deployed on any host This facilitates: –Debugging of the context-aware applications in the usual networked environment (without having to physically move between regions) –Evaluating the scalability of the application (test with hundreds/thousands of fake mobile devices)

11. 11 von 15 Information of Device’s Context Monitor Application Monitor Application CIS

12. 12 von 15 Context Notification - Polling Monitor Application Monitor Application CIS ??? EnergyLevel 5000 ??? EnergyLevel = 28 FreeMemory = 6000

13. 13 von 15 Context Notification – Publish/Subscribe Monitor Application Monitor Application CIS EnergyLevel 5000 EnergyLevel > 20 and FreeMemory > 5000 EnergyLevel = 18 FreeMemory = 6000

14. 14 von 15 Context Model Automatically Collected Hardware Context Variables CPU Usage (%); Battery Energy Level (%) ; Free Main Memory (KB); Advertisement Periodicy – Monitor (seconds); Delta T – context freshness (ms); Acess Point Mac Address (Mac Address); OnLine (boolean); Other devices

15. 15 von 15 Context Model Automatically Collected Hardware Context Variables IP Change (boolean); AP Change (boolean); Roaming (boolean); List of Available Acess Points (Array); AP Mac Adsress (MAC Address); RSSI (Integer); SSID (String); Static Hardware Context Variables Device Type (String); ScreenSizeWidth (Integer); ScreenSizeHeight (Integer); ColorCapable (Boolean); BitsPerPixel (Integer)

16. 16 von 15 Adaptations for the Use Cases „The Closest Place“ service –Functionality Find the closests place to the user –Examples Hotels, restaurants, car rentals, „luggage locks“, public transpostation stations, information services, touristic attractions, bike rentals, pharmacies, doctors and hospital –Context Variables User‘s location, place location „Wheather Forecast“ service –Functionality Find the whether forecast information to specific places –Context Variables Place location „Personalized News“ service –Functionality Set the News broadcast to a specific country Set the language for a News broadcast –Context Variables Home Location, Mother Language

17. 17 von 15 Adaptations for the Use Cases „Screen Expansion“ service –Functionality Expand the display of a device to a another device (netbooks or notebooks) –Context Variables Display Size, Available Devices „Automatic Route Calculation for Agenda Appointments“ service –Functionality Calculate the route to the address of the next appointment in the agenda –Context Variables Current Location, User Profile Options (fit or green) „Cheap Citesseing“ service –Functionality Find a citeseeing which covers the citeseeing of a city wiht public transportation –Context Variables Current Location, Public Transportation Available in the Location, Location of Touristic Attractions

18. 18 von 15 Adaptations for the Use Cases „Automatic Ticket Buying“ service –Functionality Buy transportation tickets automatically based on the proximity of the device to special buying places „I am in hurry“ service –Functionality Calculate the fastest route to a location, based on the period of a day and traffic data –Context Variables Current User Location, Period of the Day, Traffic Statistic Service of the Current User Location „Battery Saving“ preference –Functionality Stop streaming services or change them to less consuming bandwidth/battery services Change the brightness level of the display –Context Variables Battery Level, Bandwidth Threshold Current Location, Visual Impairment Preference

19. 19 von 15 Adaptations for the Use Cases „Special Eating“ preference –Functionality Find special kinds of restaurants: vegetarian, steaks, nuddles or paellas –Context Variables Current User Location, Restaurant Locations „Movement Impairment“ preference –Functionality Find less walking routes Find stations which support transit of impaired people –Context Variables Current User Location, Current Location Station Information, Destination Location „Visual Impairment“ preference –Functionality Display bigger icons in the screen Enable machine speaking mechanism Change the brightness level of the display Change the ilumination of the keyboard –Context Variables Screen Size, User Visual Impairment, Environment Light Level

20. 20 von 15 Adaptations for the Use Cases „Fit Feeling“ preference –Functionality Rank the kinds of transporation based on movement (1. Walking, 2. Bike) –Context Variables Current User Location, Destiny Location, Physical Level Movement of the Transportation „Green Conscience“ preference –Functionality Calculate routes based on the CO2 emission –Context Variables Current User Location, Destination Location, CO2 Emission of the Local Transportations

21. 21 von 15 Conclusion A middleware (MoCA) which supports the development of context-aware applications An extensible context model to gather specific context information Future context-based scenarios for the CRUISe project based on MoCA