cool: a context ontology language to enable contextual interoperability thomas strang, claudia...

CoOL: A Context Ontology CoOL: A Context Ontology Language to Enable Contextual Language to Enable Contextual InteroperabilityInteroperability

Thomas Strang, Claudia Linnhoff-Popien, and Korbinian Frank

German Aerospace Centor (DLR). Oberpfaffenhofen, Germany

Ludwig-Maximilians-University (LMU), Munich, Germany

Presented by Sangkeun Lee IDS Lab.

Copyright 2008 by CEBT

IntroductionIntroduction

The pervasive computing trend is driving a need for context-aware service architectures involved in a service interaction

To reduce the amount of required user actions

Various actors

– E.g. any user, any service provider, environment, or third parties

A key to context information in context-aware system is a

Well designed model to describe contextual facts and contextual interrelationships

Previous works lack formality

The context modeling approach in this paper tries to close the formality gap by using Ontologies

Another example: CONON (Context Ontology)

IDS Lab. Seminar - 2Center for E-Business Technology


What is Context?What is Context?

Definition of Context Information

“A context information is any information which can be used to characterize the state of an entity concerning a specific aspect”

“An entity is a person a place or in general an object”

“An aspect is a classification, symbol or value-range, whose subsets are a superset of all reachable states”


Reference: “Trends in Mobile Computing From Mobile Phone to Context-Aware Service Platform” by Thomas Strang


What is Context? (cont’d)What is Context? (cont’d)

Definition of Context

“A context is the set of all context information characterizing the entities relevant for a specific task in their relevant aspects”

“An entity is relevant for a specific task, if its state is characterized at least concerning one relevant aspect”

“An aspect is relevant, if the state with respect to this aspect is accessed during a specific task or the state has any kind of influence on the task”




Context-awarenessContext-awareness

Definition of Context Awareness:

“A system is context aware if it uses any kind of context information before or during service provisioning or service usage”

Two main benefits from Context Awareness:

Adaptation of services to changes in environment

reduces amount of interaction with user

– Improvement of UI (particularly on small mobile devices)




Ontologies and the Context Ontology Ontologies and the Context Ontology LanguageLanguage

Challenge to describe contextual facts and interrelationships in a precise and traceable manner

“print document on printer near to me”

It is required to have a precise definition of terms used in the task, particularly what “near” means to “me”

It is highly desirable that each participating party in a service interaction share the same interpretation of the meaning “behind” it

– Shared understanding

Ontologies

May be stored at different places and created by different authors, which offers flexibility and extensibility



Context Ontology Language (CoOL)Context Ontology Language (CoOL)

CoOL Core

OWL and DAML+OIL

F-Logic

CoOL Integration

A collection of schema and protocol extensions as well as common subcontepts, enabling the use of CoOL Core in several service frameworks (e.g Web Service)

Out of focus of this paper

Having a projection of the model in multiple ontology languages enables that

Developer may use any of languages which seems to be adequate

– Using OWL because of wide range of available tools

– Using F-logic because of its rule based extensibility



ASC ModelASC Model

Aspect-Scale-Context (ASC) model

Named after the core concepts

Each aspect aggregate one or more scales

Each scale aggregates one or more context information

hasAspect, hasScale, constructedBy



ASC Model ExamplesASC Model Examples


Reference: “Ubiquitous Computing :Context and Context-Awareness”, University of Innsbruck, Lecture slide from SS 2005

Another Example:SpartialDistanceAspect - MeterScale,KilometerScale – 10, 20

Fahrenheit's temperature scale Celsius temperature scale

Specific Values


OperationsOperations

IntraOperation

Mapping function from one scale to at least one other of the already existing scales of the same aspect

InterOperation

Scales which require access to scales of one or more other aspects can be defined using InterOperations

E.g.

– “KilometerPerHourScale” of a “SpeedAspect” can be defined by using an InterOperation with two Parameter, delta_s and delta_t where

delta_s is from an aspect “SpatialDistanceAspect”

delta_t is from an aspect “DurationAspect”

MetricOperation

Compare two context information instances



Transfer ModelTransfer Model

ASC model may be used as transfer model to employ the knowledge expressed in other context models

Example: Henricksen

Context extension to the Object-Role Modeling approach

The basic modeling concept in ORM is fact

Henricksen extended ORM to allow fact types to be categorized either as static or dynamic (profiled, sensed, derived)

Using ASC Model

Facts can be modeled as “context information”

Classification can be mapped by introducing a “quality aspect” consisting the element {static, dynamic profiled, dynamic sensed, dynamic derived}

dependOn relation can be expressed using Intra/InterOperations



Relation to DAML-SRelation to DAML-S

DAML-S : ontology of services

ServiceProfile, ServiceModel, and ServiceGrounding

Extension: ServiceContext

– May serve as a formal description of a service’s contextual interoperability by providing a comprehensive but extensible model based on the ASC model



Motivation: Motivation: MNM Service Model and the Context ExtensionMNM Service Model and the Context Extension



System ArchitectureSystem Architecture


The authors focus on the context provider domain as introduced in the previous page


Discussion & ConclusionsDiscussion & Conclusions

Discussion

ASC model

– The authors gives us a different point of view (compare to CONON)

– What’s weak points and strong points?

It is interesting the authors classified actors into

– Context Providers, Service Providers, Customers

– Who can be Context Providers?

Conclusions

The authors introduced ASC model as a base model to express how some context information can be used to characterize the state of an entity concerning a specific aspect

ASC model fits into a general purpose service model

– Context Extension : Making any service interaction based on that model context-aware

ASC model as transfer model


cool: a context ontology language to enable contextual interoperability thomas strang, claudia...

Documents

context awareness

contddefinition of context

contextaware service

contextaware system

kind of context information

ebusiness technologycopyright

conon context ontologyids

ebusiness technologyreference