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1
Smart Campus Systema Proposal for a Context-Aware Ap-plication
Sangkeun Lee
Sungchan Park
IDS Lab, SNU
Copyright 2008 by CEBT
Introduction
Smart Campus System
supports development, maintenance, and delivery of context-aware services in university campus
aggregates context data in university campus so that context-aware application can exploit them
provides model and tools for designing context-aware services running on our system
Why do we choose university campus as a domain?
it provides good foundations for operating context-aware services
is well organized area with large size, and large number of people spends most of their time within the area
Semantic Tech & Context - 2
Copyright 2008 by CEBT
Motivating Scenarios
we built some various realistic context-aware application scenarios, and studied the requirements of our system based on the scenarios
Each scenario has its own characteristics which show what our system should support.
4 Scenarios
Preparing iced coffee
Bus stop
Cafeteria information
Personalized department office
Semantic Tech & Context - 3
Copyright 2008 by CEBT
Motivating Scenarios: Preparing iced Coffee
Scenario
On a very hot and humid day, A is returning to his dormitory room by shuttle bus. When 5 minutes left to arrival, his PDA rings alarm sound with displaying the following message: “It is very hot day. Is it O.K. to prepare a cup of iced coffee at your room? Yes/No” He clicks “Yes” and the coffee pot in A’s room starts to make some iced coffee. When A arrives at his room, U-home terminal attached on wall notifies that the iced coffee is prepared with voice.
Semantic Tech & Context - 4
Device Collaboration
possibility of different device composition
Copyright 2008 by CEBT
Motivating Scenarios: Bus Stop
Scenario
A just has arrived at the bus stop. At the moment, A’s cellular phone rings alarm sound with displaying the following message: “Waiting time info: circulation shuttle bus arrives in 10 min. commuter bus arrives in 5 min.”
A clicks on ‘bus waiting time info’, PDA displays the waiting time information of the nearest bus stop.
Semantic Tech & Context - 5
real-time synchronization with real world
Level of autonomy
Copyright 2008 by CEBT
Motivating Scenarios: Cafeteria In-formation
A is sitting at his desk in his laboratory, and it is 11:50 AM—it is close to lunch time. He usually checks the number of available seats in the cafeteria or length of waiting queue. But he does not do so today since he is busy now. At that moment, the following message is displayed on the monitor of his desktop computer: “The lunch time is close. Would you like to check the current status of the cafeteria? Yes/No”
Semantic Tech & Context - 6
Prediction based on historical user record
Copyright 2008 by CEBT
Motivating Scenarios: Personalized Depart-ment Office
A has forgot applying “graduation exam”. If he does not apply by tomorrow, his graduation will be delayed one semester. When A comes to laboratory at 10 o’clock AM and logs in his desktop computer, the monitor displays the following message: “Notification from department office of computer science: You should apply “graduation exam” by tomorrow. If not, some problem can occur related to your graduation.”
Semantic Tech & Context - 7
Virtual information as context information
Context Fusion (Virtual + Physical Sensor)
Copyright 2008 by CEBT
Common Issues
Terminal selection
If the user sits at the desk, the desktop computer is most relevant terminal. If the user carries his PDA, the PDA is most relevant terminal
Identifying the entities
System should be able to identify many entities, like shuttle bus, cafeteria, and students and so on
RFID Tags, Distributed Sensors
Processing user feedback
important for maintain and enhancing services
The infrastructure should support the development
Semantic Tech & Context - 8
Copyright 2008 by CEBT
Smart Campus System
Our Smart Campus System
Gathers context-information from various sources
Handles the abstraction level of context data
Provides efficient ways of storing and managing context data
Is flexible and easily configurable
– System administrators can easily add new context-aware services or configure existing services
Provides the most appropriate service or content to users without user’s too much intervention
Supports graphic user interfaces for mobile and desktop environments – both for system administrator and users
Semantic Tech & Context - 9
Copyright 2008 by CEBT
Technical Issues
Centralized (Context Server) vs. Decentralized (P2P Network)
Dealing with Heterogeneity
many different devices should be able to smoothly communicate with each other
Abstraction and standardization
Semantic Tech & Context - 10
Copyright 2008 by CEBT
Technical Issues
Performance & Scalability
If the system can’t support acceptable performance and scalability, then it can’t be a practical and useful system
many sensors generate large number of signals, and the signals should be handled in real-time
Historical context data & User behavior log
Context-aware services are basically real-time based, however, historical context data and user behavior log can be used as very useful data for the services
Privacy Protection
some users may feel uncomfortable that the system can use or open their information without any notice
privacy policy is required
Semantic Tech & Context - 11
Copyright 2008 by CEBT
Smart Campus System
We reckon the ‘Context Server’ approach as a more suit-able method for our Smart Campus System
Campus System can be unified to the legacy system
the congestion problem, and low fault-tolerance problem can be relatively easily solved than the problems of P2P approach like handling dynamicity of constructing commu-nication networks
We present Server-Client Architecture
Semantic Tech & Context - 12
Copyright 2008 by CEBT
Smart Campus System - Server
The server-side system is the core of Smart Campus System and responsible for:
Mediating communication among devices
Gathering context data from various sources
Handling the abstraction level of context data
Managing context data
Triggering services based on service rules
Running service descriptions
Managing service descriptions in the service repository
Logging historical context data and user behavior
Providing graphic user interface for users and system administrator
Semantic Tech & Context - 13
Copyright 2008 by CEBT
Smart Campus System - Server
Interface
works as a communication abstraction layer among devices
virtual devices which are actually software modules can be used just like other devices through the interface
Context Manager
controls the abstraction levels of context information based on predefined Context Rules
manages context data in database
To enable the semantics of context data, Smart Campus System uses the Vocabulary Ontology
Privacy Manager
protects illegal access of context data based on privacy policy.
Privacy policy specifies what context data is allowed to whom or what devices or services.
When a device or a service requests context data to Context Manager, Privacy Manager checks if the requested context data is allowed. Context Manager provides the data only when it’s allowed according to the privacy policy.
Semantic Tech & Context - 14
Copyright 2008 by CEBT
Smart Campus System - Server
Service Trigger
monitors high-level context information transformed by the Context Manager.
A Service Rule specifies what kind of service should be triggered in what context.
Service Repository
is where context-aware service descriptions are stored.
A service description is represented in Context-Aware Service Description Language (CASDL).
CASDL is a script language for describing details of such as the required context data for performing the service, detailed service process, communication among devices, and the final output format.
Service Processor performs actual service processes according to the service description. Service Processor sends the processed results to the target service terminal specified in the service description.
Log Manager manages all the logs of changes in context data, user behavior
Semantic Tech & Context - 15
Copyright 2008 by CEBT
Smart Campus System - Server
Semantic Tech & Context - 16
Log Manager
Real World EnvironmentWWW
Location
Temperature PressureAltitude
Sensor Sensor Sensor Virtual Sensor…
Interface
Humidity
Device (Client)Device (Client)
Device (Client)Device (Client)
Context Manager
Service Trigger
Service Processor
ContextData
Vocabulary Ontology
Service Repository
ServiceDescription
ContextRules
ServiceRules
Context-aware Service Description Language (CASDL)
Privacy Manager PrivacyPolicy
Log
Copyright 2008 by CEBT
Smart Campus System - Client
The client-side system
Relatively Simple
should be able to be deployed in mobile devices,
should have light and simple architecture
The client-side system is responsible for:
Communicate with the server-side system
Processing the requests from the server
Providing interactive graphic user interface
Semantic Tech & Context - 17
Request Processor
Interface GUI
Server
Legacy System
Copyright 2008 by CEBT
Service Process Flow
Semantic Tech & Context - 18
Sensors in Shuttle Bus send signals to Smart Campus Server:
Temperature, User’s presence, … Context Manager abstracts the signal and store in
database:
Ex) Temperature > 25 & Humidity > 70% => Weather is hot
Service Trigger monitors catches the situation and trigger(create a service instance) “Preparing iced cof-fee” service according to service rules
Service Description of “Preparing iced coffee” is loaded into Service Processor
Service Processor interacts with other devices, accord-ing to loaded service description: Coffee pot, Ice Maker, …
Sensors in user’s room notices that the user has ar-rived and send the signal to Smart Campus Server
U-home Terminal notifies the user when the iced coffee is ready
End of Service
Smart Campus System
CASDL
Copyright 2008 by CEBT
Development Plan
Semantic Tech & Context - 19
Copyright 2008 by CEBT
Conclusions
We presented
the proposal of Smart Campus Project for providing context-aware services in university campus
motivating scenarios
main functionalities
technical issues and showed how we will handle the issues.
high level architecture of Smart Campus System and Service Process Flow
Although we presented a domain-specific application proposal, the ultimate aim of this project is to explore unseen issues on realizing context-aware services
We conclude that actual implementation will also provide us good insight for realizing general purpose large-scale context-aware systems
Semantic Tech & Context - 20