Management of User Preferences and Conflicts to Ubiquitous

Applications Adaptation

Salima Bourougaa-Tria

, Hassina Seridi-Bouchelaghem

and Farid Mokhati

Tebessa University, LAMIS Laboratory, Tebessa, Algeria

Annaba University, LabGED Laboratory, Annaba, Algeria

Oum el bouaghi university, LAMIS Laboratory, Oum El Bouaghi, Algeria

Keywords: Context of Use, User Profile, Web-based Information System, Nomadic Environment, Ontology, User

Preferences, Conflicts, Ubiquitous Computing, Web Service.

Abstract: Ubiquitous computing is a recent research domain that has attracted interest from several researchers. Its

main objective is allowing users to access data anytime, anywhere, in particular using Mobile Devices

(MD).Applications in this domain are sensitive to the context and must be able to perceive it to adapt their

behaviours to this context, taking into consideration data that deals with the context of use and user

preferences. Data about context of use provides in particular a conditions description (temporal, spatial,

hardware, etc.) under which the user accesses Information Systems (IS). Data about user preferences aims at

expressing what the user would like to obtain from the system considering different aspects (activities

display, etc.) to meet nomadic users’ expectations. In this paper, we attempt to answer this problem by

proposing a novel approach allowing essentially: (1) representing the semantic context and nomadic user’s

preferences through a novel proposed ontology, (2)resolving conflicts that may arise between user

preferences and, (3) adapting such applications to the context of use and user’s profile by adapting the

user’s request.

1 INTRODUCTION

Currently, Web users access to a large mass of

invarious data situations through distinct devices, to

have answers to their requests that are usually very

numerous, from multiple sources of information

(heterogeneous and remote). Such answers are not

all equally interesting and relevant, and they do not

answer all the user’s wishes, which may decrease the

user satisfaction. This complexity is increased if the

user is nomadic (user who frequently changes

localization) and appealed SIW (System Information

on the Web), anywhere and anytime via mobile

devices (PDAs, phones, laptops) because the change

of localization, for example, causes a change in

working conditions and consequently a change in the

general context of use. What incited developers to

integrate these mobiles devices into their

applications, giving rise to new information systems

called pervasive or ubiquitous.

In this case, these applications must taking into

account the user’s situation called contextual

situation. This latter includes the context of use as

well as information on its profile. To adapt all

applications behaviours to a situation for returning to

the user a relevant response from the content point

of view and time, it is the subjacent idea of

ubiquitous computing, where applications are

sensitive to the context (context-aware applications).

In this context, ensuring access by nomadic users

to information Systems through various devices and

the adaptation of responses to nomadic users profile

and context of use are two bound problems.

Nevertheless, tree aspects can be approached by the

following questions:

 How to model the context of use and the

nomadic user profile?

 How to resolve conflicts that may arise between

users’ preferences?

 How to adapt the context-aware application

behaviour to satisfy the needs of these mobile users?

In order to answer these questions, we propose an

approach which includes:

 Ontology to modelling the context of use and the

user’s preferences based on a new definition of the

271

Bourougaa-Tria S., Seridi-Bouchelaghem H. and Mokhati F..

Management of User Preferences and Conﬂicts to Ubiquitous Applications Adaptation.

DOI: 10.5220/0004010802710276

In Proceedings of the 14th International Conference on Enterprise Information Systems (ICEIS-2012), pages 271-276

ISBN: 978-989-8565-11-2

 2012 SCITEPRESS (Science and Technology Publications, Lda.)

context which separates the application data from

the contextual data.

 The conflicts resolution solution.

 A Web Service based architecture to ensure the

dynamic functional adaptation of Web service-based

context-aware applications.

The remainder of this paper is organized as follows.

In Section 2, we gave a brief overview of major

related works. We present the architecture in section

3. We detail the static part of our approach in

Section 4. Section 5 details the dynamic part of the

system. We explain the implementation of our

approach in section 6.We discuss in section 7, our

actual research, draw some conclusions and give

some future work directions.

2 RELATED WORKS

We distinguish four categories of context modelling

approaches: The first consists in storing the context

by using key-value pairs (attribute, value) or by

using a set of triplets. The category of the model-

oriented approaches includes: Markup Scheme

Models, graphical Models and Object Oriented

Models. The third category represents the context by

a logic-based model. The last category models the

context by using ontologies, the most referred

modelling are: CoBrA-ONT by (Chen, 2003),

SOUPA by (Chen, 2004), and ontologies of PUMAS

a framework based on the agents proposed by

(Carrillo, 2007).

In (Belhanafi, 2006), we find a synthesis on the

characteristics of the context modelling approaches

and this let us deduce from it that in spite of the

principal disadvantage of the ontology approaches

which is the ontology’s complexity execution and

the reasoning weight on their facts and their entities.

They are most expressive and most promising for

context description in an environment sensitive to

the context. This is our motivation to choosing

ontology in context modelling in this work.

Those works have considerably forwarded the

domain by proposing novel strategies for context

modelling. However, they omit some important

aspects which can be summarized as follows:

 None of existing ontologies of context modelling

separate between the context data and the

applications data. According to (Chaari, 2006), this

separation is very necessary for a reliable modelling

of context.

 The user’s preferences management considered

only by PUMAS (Carrillo, 2007). Although, it

represents a very important point to satisfy the user

and to return to him answer adapted to its context.

 The conflicts’ resolution is considered only by

PUMAS (Carrillo, 2007). It defined some conflicts

and presents their corresponding solutions. But this

approach does not solve this problem, because it has

not considered all conflicts which can arise during

the user’s preferences checking.

3 CONTEXT-AWARE

MODELLING AND ADAPTING

APPROACH ARCHITECTURE

The approach presented in this paper is focused on

three important activities:

 The modelling of the context of use and the

users’ preferences based on a new definition of the

context which separates the application data from

the contextual data.

 The resolving of conflicts.

 The dynamic functional adaptation of web

service-based context-aware applications.

Consequently, our approach consists of two parts

(Figure 1):

 A Static Part: focuses on the contextual

information modelling of users and especially the

preferences and conflicts management which can

arise between the user’s preferences during their

check.

 A Dynamic Part: assures the functional

dynamic adaptation of these context-sensitive

applications to the various user’s contextual

situations and aims to better respond its needs.

According to figure 1, the application adaptation to

context of use and the user’s profile passes by 16

steps which will be explained in the following

sections.

4 THE STATIC PART:

MODELING CONTEXT AND

CONFLICT MANAGEMENT

In this section, we present the static part of our

approach modeling the context and managing

conflict, which accedes to application in the

ubiquitous computing field, where applications are

sensitive to the context: “context-aware

applications”. We opted for a semantic

representation of the context of use and the

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Figure 1: Architecture of our approach.

profile of user, which involves the use of ontologies.

Because this representation focuses on relationship

between information content, allowing inferences of

other information, in order to adapt information to

this context of use and user profile. We built light

general context ontology to represent contextual

information. For the ontology developing, we

followed the ontology methodology construction

(Kassel, 2002) following three steps:

conceptualization, ontologization and

operationalization.

The conceptualization consists of identifying in a

corpus the knowledge to determinate domain

(Farquhar, 2000).In the sensitivity to the context

domain, the corpus contains only definitions.

Researches in the context-awareness domain have

not yet led to a generic and pragmatic definition of

context. So, several definitions for the context were

advanced (Pittarello, 2005) and (Chaari, 2006). The

definitions issued so far are very abstract or very

specific to a particular domain, making the

formalization of the context very difficult. The (Dey,

2001) definition is widely accepted as a “good”

definition. According to (Chaari, 2006), definition

does not help in separating the contextual data from

the application data, and the core of the application

should be designed in a context independent way.

This separation according to (Chaari, 2006) is very

important, before beginning the design of an

application sensitive to the context. A data defined

as contextual in a field can be a data application in

another field. Separation between the contextual data

and the application data is also important for the

modelling of the context. Consequently, the

determination of the most descriptive concepts of

information which constitutes the context, we chose

the separation of the contextual data of the

application data according to the definition of

(Chaari, 2006) of the context, because it seems to us

relevant and generic.

According to our corpus, we can divide the

concepts of the context into two parts: the concepts

which represent the context of use of a user and the

concepts which represent the user profile.

The “context of use” in our approach presents

the set of data which allows indicating the situation

of the user when it connects to the ubiquitous

application. It is represented by the following

concepts: The user; the session; the used mobile

device (MD) and location of the user.

The “user profile” is present by a set of preferences

of user. We detail these concepts in the following

sections.

4.1 User Preferences: Definition and

Types

We define two types of preferences:

4.1.1 Activity Preferences

Describe how the user plans to perform its activities in

the system. We define this type of preferences as

follows: During his first contact with our system, the

user can define the contents of each of his

preferred

activities.I.e. The user can define from the

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beginning when he asks the activity "A" what implies

automatically the contents: C1, C2 ....Etc.

Activité (A) Æcontents (C1, C2,…….etc.)

Therefore, the preferences of activities are

represented as follows:

Activity_Preference (A, {content}, {associated_

Activities}).

{Content}: is a list of the contents defined by the

user from his first contact with our system .A: is the

Activity which the user wishes to carry out in the

system. {Associated_ Activities} is a list of the

associated activities which the user wants to execute

if he asks the activity A.

4.1.2 Display Preferences

Display Preferences describe how the user wants the

information to be displayed on his MD (for example,

the user only wants information in text format). At

every activity is associated a Display preference. It

is represented as follows:

Display _Preference (format, characteristics)

Format which can take the value: "video” ,”text",

"image", "sound". Each format is based on a set of

characteristics.

The user profile is represented by the Activities

preferences and Display preferences.

4.2 Conflict: Definition and Types

By conflict we refer to problems which can arise

during the verification of user preferences. For

example, if a user demands activities which are not

suitable for access rights, he can receive nothing.

For these problems (conflicts), we offer some

suggestions to solve them. At every type of conflict

is associated a solution. It is represented as follows:

Conflict (Type, Solution, Suggestion)

 Type; represent the conflict which can arise.

 Solution; allows defining how to take action to

resolve the conflict that occurred.

 Suggestion: represents the proposal of the user in

cases where the system cannot find a solution to the

conflict that occurred.

Our approach manages five conflicts which can be

arising between the user preferences during the

check of these last ones.

Figure 2 illustrates the context ontology called

'ContoLogy' that we proposed using UML class

diagram.

Figure 2: UML class diagram of the ontology of profile

“ContoLogy”.

5 THE DYNAMIC PART:

ADAPTING UBIQUITOUS

APPLICATIONS

In this section, we present the dynamic part of our

approach for adapting the ubiquitous applications to

the user’s context and the user profile. This part

assure the functional dynamic adaptation of these

applications sensitive to the context of use and the

profile of user, in the various contextual situations of

a user has at the end to meet the expectations better

of this last one.

This adaptation is assured by the adaptation of

the user request to the context of use and the user

profile. The context of use of a user witch accedes to

a ubiquitous application, in addition to being

composed of multiples aspects, is very variable and

in constant evolution, which returns the operation of

adaptation of the application in question a difficult

task. In order to ensure this process of adaptation

and to be able to change the behaviour of such

application sensitive to the context of use, we

propose:

 Using Web Services (Ponge, 2004) during the

development of this type of application.

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 Using in the dynamic part of our approach, a

module composed of three web services, and two

modules for detecting the context: Context

integration and context sensor.

The dynamic part is composed of three Web Services

as follows: Preferences Manager WService, Conflicts

manager WService and WService Adapter, Context

integration and context sensor. These modules

assure:

 The adaptation of the user request to the context;

 The resolution of conflicts;

 Returning an answer adapted to the context to the

user.

5.1 Preferences Manager WService

This Wservice is charged of the management of the

preferences. It checks conformity between the access

rights of the user, the characteristics of his used MD

and the specified preferences.

5.2 Conflicts Manager WService

This WService has as role to manage the conflicts

that may arise between user preferences. The

conflicts are managed by our approach according to

the following sequence diagram (See figure 3). It

ensures:

 The resolution of conflicts;

 Sends the solution of conflicts;

 The storage of information on the conflicts

which have occurred.

5.3 Adapter WService

It represents the principal WService of our

architecture. It executes the flowing steps to obtain

the answer to the request of user:

 Access to the Web Services of the application.

 Research on the WSDL of these latter, in order

to extract WServices with their interfaces, their

operations and the number of interfaces specific to

each Web Service

 Select the WS which answer better the request of

the user.

 Reformulate and sends the adapted answer to the

context of use.

5.4 Context Sensor

This module is responsible for capture the context of

the user at the time of a connection, namely:

localization, MD, session. Then sends these

contextual information to the module “Context

integration”. It is composed of two S/modules: 1)

Logical context sensor: a set of interfaces used by

the user to enter his context. 2) The physical context

sensor: a set of physical dispositive used to capture

the context of the use.

Figure 3: conflict sequence diagram.

5.5 Context Integration

This module ensures:

 Receive the initial request of user.

 Reformulates the initial request of the user by

adding the contextual information

 Sends the contextual request.

6 IMPLEMENTATION

In the implementation phase, we followed the

following steps: Firstly, we created the context

ontology “Contology”, using the editor

PROTEGE2000 (Protégé, 2000) As a result of this

step we obtained the OWL File that will be used by

SPARQL queries. In step2, we developed a web

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service-based application for managing a travel

agency and Online reservation. This application will

be used by our system for the adapting to the context

of use and the profile of user.

7 CONCLUSIONS AND FUTURE

WORKS

The ubiquitous computing focuses on the use of two

essential notions: user profile and context of use, in

order to satisfy better the demands of the nomadic

users. Furthermore, a reliable modelling of such two

notions and an adaptation of the application

behaviour to them are two required processes. In this

paper, we presented a novel approach that allows, on

one hand, modelling the context of use and the user

profiles using an ontology we proposed, and, on the

other hand, resolving the conflicts using some

proposed solutions. An architecture illustrating the

dynamic adaptation of web service-based ubiquitous

applications is also proposed.

As future directions to this work, we envisage to

complete the development of our approach by using

the context ontology and the developed application

for the management of a travel agency and

Online reservation.

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