Lyon Research Center for Images and Intelligent Information Systems

IEEE International Conference on Pervasive Services 2006

FRE 2672

INSA Lyon

ICPS, 27 June 2006

Modeling and Using Context in Adapting Applications to Pervasive Environments

Tarak Chaari, Dejene Ejigu,

Frédérique Laforest and Vasile-Marian Scuturici

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OUTLINE

Introduction

The scope of this paper

Context Modeling

Adaptation strategy to context

Implementation

Conclusions

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What is context?

Fuzzy and general word

Where are we? What we are doing? …

1996, Brown’s definitionLocation, identity, application and time

2001, Dey’s definitionAny information characterizing an entityAn entity is a person, a location, an object… The most general and adopted definition Too vague and it does not help modelling the context

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context definition and properties

Definition: context is the set of external parameters that can modify the behaviour of an application by defining new views on its data and services

Wingorad: something is context because of the way it is used in interpretation, not due to its inherent properties

Example: GPS coordinates in a healthcare application / in traffic regulation application

Context parameters are transparent to the user

New instance = new contextual situation

These precisions help adding context – awareness to non adapted application

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Context – Awareness

Definition The ability of acquiring context knowledge adaptation to the context change

Requirements Capture Interpret Store/Disseminate Adapt

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Motivations

Existing solutions specific to particular concerns a lot of interest on how to capture context

Lack of a comprehensive context model formality expressiveness

Lack of a concrete approach to adapt applications to context

generic adaptation strategy dynamic adaptation

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OUTLINE

Introduction

The scope of this paper

Context Modeling

Adaptation strategy to context

Implementation

Conclusions

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SECAS Project

Simple Environment for Context – Aware Systems

Generic and comprehensive platform

Creating new context-aware applications

Adapting existing legacy applications to new contexts

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SECAS Architecture Domain definition

interface (DDI)

domain ontology

components

domain specific rules

Terminal

Adaptation

Application core

application data sources

core services

context consumer adapter

subscribe() push() pull()

Context management

context providers

context interp reters

context manager broker

Application’s UI

UI widgets

application manager

Data/control flow Is a

Adaptation services

Functional Model

context ontology, instance and history

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OUTLINE

Introduction

The scope of this paper

Context Modeling

Adaptation strategy to context

Implementation

Conclusions

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Context Modeling

Context = (Subject, Predicate, Value, Time, Certainty)

Example= (Bob, isLocatedIn, room305, Fri-23-jun-2006-12:00:00-GMT, 0.85)

Intelligence and semantics processing (VideoService, runsOn, PDA-01) (PDA-02, runs, VideoService) (realPlayer, runsOn, laptop-01)

devices that can run Video Services

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Ontology for context modeling

Static Low level Context

Dynamic Low level Context

Deduced High Level

Context

Context interpreter

Context manager Context to knowledge conversion

Domain Specific Rules

Context -aware

Service

Rule to ontology mapping

Context History DB

Context Ontology

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Example of a context ontology

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OUTLINE

Introduction

The scope of this paper

Context Modeling

Adaptation strategy to context

Implementation

Conclusions

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Application’s Functional Model

Functional Model = application services description + services dependences

XML deployment descriptor (extension of pnml)

Authentication

RecordInfo RecordImages

displayTemperatures

PatientList

userID is not null

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Service Adaptation strategy

Initial Functional Model

Adapted Functional Model 1

Adaptation entities

Adapted Functional Model 2

Adapted Functional Model 3

Context situation 1

Context situation 3

Context situation 2

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Service adaptation entity

Adapter (proxy)

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Service adaptation rules

Pairs (context situation, adaptation action)Context situation = Logical expressions of context predicatesAdaptation action = a list of adaptation operators

Operators on the functional model Operators on the inputs and outputs of services Operators on service versions

Example

//context situation ¬acceptContentType(actual_device, ‘image’) hasService(actual_application, ?S) hasOutputVector(?S,?Ov) hasParameter(?Ov,?P) hasType(?P,’image’) //adaptation action hasAdaptation(actual_application, ?A) hasOperator(?A,”lockService”) hasAdaptationParemeter(?A,?S)

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OUTLINE

Introduction

The scope of this work

Context Modeling

Adaptation strategy to context

Implementation

Conclusions

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SECAS Administration User Interface

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Context1: Doctor1 using SICOM on a standard PC

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Context2: Doctor1 using SICOM on a smartPhone

E1 E2 E3 E4

E5 E6 E’6

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OUTLINE

Introduction

The scope of this paper

Context Modeling

Adaptation strategy to context

Implementation

Conclusions

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Conclusions

A comprehensive Context model based on ontology representation

An extensible adaptation platform to: create context – aware applications adapt existing applications to context

Platform under development Services adaptation module completed and validated Content adaptation module User interface adaptation module

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Question time !

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