An Approach for Configuring Ontology-based Application Context Model

Chung-Seong Hong, Hyun Kim, Hyoung-Sun Kim

Electronics and Telecommunication Research Institute, Republic of Korea

Hyun-Chan Lee

Hongik Univ., Republic of Korea

Introduction

■ Ubiquitous Computing Vision■ “The most profound technologies are those that disappear. They

weave themselves into the fabric of everyday life until they are indistinguishable from it.” (Mark Weiser, 1991)

Embodied Reality(ubiquitous computing)

Contexts and Context-Aware System

■ In Ubiquitous Computing Environments,■ It is generally agreed that context-awareness should be simulated in comp

uting systems to strengthen their capability to communicate, to behavior and to process information.

■ Contexts [Dey et. al. 2001]■ Context is any information that can be used to characterize the situation of

an entity.■ Three Fundamental Elements for characterizing the situation

▣ Environments - Location, Building, Room, etc.▣ Computational Entity – Smart Sensors, Actuators, etc.▣ User – Profile, Schedule, Activities, etc.

■ Context-Aware System■ A system that uses contexts to provide relevant information and services

to user

Three Phases of Contexts Manipulation in the Context-Aware System

Problem Definitions

■ Backgrounds■ Previous researches mainly focus on the collecting and analyzing

context information from the computational devices.■ Contexts are managed and interpreted inside of the

infrastructure with their own context model.■ Applications are created and executed based on the unified

context model that is managed in the context-aware infrastructure.

■ Problems■ With the unified context model,

Is it possible to support all kinds of ubiquitous applications?■ What about contexts outside of the context-aware system?

▣ Information System - Scheduling Sys., Weather Forecasting Sys., etc.▣ Web Services

Goals

■ Goals

■ We propose a conceptual modeling approach

focusing on how to configure application context model

using ontology

through expanding context-aware systems’ context model

for intelligent services in ubiquitous computing environments.

■ A new context modeling approach is designed to overcome shortcomings such as

▣ context inference through OWL▣ context knowledge reuse through context modularization▣ context knowledge expansion through ontology merging

■ We simplify the application context model as four-layered space based on the abstraction level of contexts.

Layered Application Context Model

Layered Application Context Model

■ Shared Vocabulary Layer■ set of shard vocabulary and their semantics

that are used in the common ontology layer are defined■ As vocabularies are shared between the infrastructure developer and the a

pplication developer, it is referenced by a application developer when he builds a context-aware application.

■ Common Ontology Layer■ The ontology concepts (i.e., classes and attributes) that are commonly use

d in various applications are modeled.■ The common ontology provides

▣ the high level ontology knowledge▣ the same aggregation and granularity to the subordinate domain ontologies

■ These concepts not only form the skeleton of context, but also act as indices of associated information because they constitute the upper level context knowledge.

Layered Application Context Model

■ Domain Ontology Layer■ The domain ontology provides

▣ the domain specific knowledge to context-aware applications▣ the metadata or schema to the subordinate instances which are located in the lowest layer.

■ This layer is composed of the infrastructure domain ontology and a set of specific domain ontologies

■ Some parts of ontology overlaps with the common ontology. ■ The specific domain ontology is about specific services, for example, the presentati

on helper service, weather service, smart home service, etc.

■ Instance Layer■ Instances of the ontology concepts are represented■ Instance layer is generally created and updated when the applications are executed.

■ By configuring the application context model when needed, we can easily build a specific application with contexts managed not only inside but also outside of the context-aware infrastructure.

Modeling Common and Domain Ontology

Prototype Smart Meeting Room Application

Ontology Merging through Overlapped TYPE Concepts

Application-SpecificOntology

(TYPE, Phased SORTAL, Material Role)

InfrastructureOntology

(TYPE, Phased SORTAL, MATERIAL ROLE)

Overlapped Ontology

(TYPE)Common Ontology

(CATEGORY, TYPE)

Integrated Application Context Ontology

The Changes of CAMUS Structure

Conclusions

■ Four Layered Application Context Model■ Modeling Common and Domain Ontology based on the Guarino’s Ontological D

istinctions■ Implementing Simple Prototype Application Context Model using Ontology■ Plans of changing CAMUS Structure for supporting Application Context Model

Context-Aware Infrastructure: CAMUS

Context-Aware Infrastructure: CAMUS

■ Universal Data Model■ Context information in the CAMUS can be represented basically

by using the UDM. ■ The UDM represents context information as nodes and

associations between them. ■ There are special nodes which have "valued" type. These nodes

can acquire values directly from class objects.