Management of User Preferences and Conflicts to Ubiquitous
Applications Adaptation
Salima Bourougaa-Tria
1
, Hassina Seridi-Bouchelaghem
2
and Farid Mokhati
3
1
Tebessa University, LAMIS Laboratory, Tebessa, Algeria
2
Annaba University, LabGED Laboratory, Annaba, Algeria
3
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
Copyright
c
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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