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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Exploring Different Use Cases for a Rich Con- text Model for Mobile Applications</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Alisa Sotsenko (Supervised by  Marc Jansen)</string-name>
          <email>alisa.sotsenko@lnu.se</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Linnaeus University, Department of Media Technology</institution>
          ,
          <addr-line>Växjö</addr-line>
          ,
          <country country="SE">Sweden</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Substantial research in the field of context modeling has explored aspects related to the use of contextualization in various mobile scenarios. The current context of a mobile user has been often limited to his/her current position, neglecting the possibilities offered by modern mobile devices of providing a much richer representation of the current user's context. This research aims to improve the usability of users' context in the mobile software development process. Therefore, this paper presents the proposal of a rich context model (RCM) as general approach for context modeling to explore the context of the users in different application domains.</p>
      </abstract>
      <kwd-group>
        <kwd>Context modeling</kwd>
        <kwd>rich context model</kwd>
        <kwd>contextualized mobile applications</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1 Introduction</title>
      <p>Modern mobile devices provide a profound set of sensors and, together with internet
connectivity, rich possibilities to present the information with respect to the users’
current needs, independently of time and space (anywhere and anytime). The context
of the user plays an important role in providing personalized services and has
considerable impact on users’ decision making. Considering a rich context information helps
to understand many user characteristics (e.g., what the user is going to do, what the
user needs to perform his/her current action, etc.) and to recommend a relevant
content/information to the user in the right time and place. The contextualization of
mobile users can enhance many of existing services and mobile applications by making
them sensible to the users’ current situation. Currently on the Android Marketplace,
more than 500 mobile applications were found, that belong to category of
personalization. The most popular and used mobile application is Personalized Launcher that
provides for users e.g., defining their custom gestures, actions for swiping on app
shortcuts, hide/show the most used/unused mobile apps, smart home screens, personal
privacy settings and more. However, current existing solutions consider limited
number of context information (e.g., current user GPS location, weather information) and
provide context-modeling techniques that mostly target a specific application domain.
Therefore, we believe that with better understanding of the users’ current context the
mobile app can better serve specific user needs. Modern mobile devices provide
possibilities to gather the context information from different mobile sensors, external
sensors connected to the mobile device via Bluetooth, smartwatch sensors, activity
tracker bands, and to extend/enrich all of this data by using additional Web Service
APIs. In our research, we define the rich context as:
“Any information that describes a situation of the user, not only received from
different mobile sensors, which could be extended by additional Web Services, but
which also derives/use a meaningful interpretation of this information for the
current user need.”</p>
      <p>The main purpose of this research is to design and explore the applicability and
reusability of a rich context model (RCM) in different application domains. This will
lead to the development of a general context model and deploy it as cloud-based
Contextualized Service that enables software developers to easily and fast develop
contextualized mobile applications. In contrast to existing approaches, our approach will
improve the applicability of the context modeling techniques in the development of
personalized mobile applications, preventing re-coding and re-designing a new
context model again and again depending on the application domain. Instead of this, the
developers should know just the target users, what the app should do and which
context data is needed to provide the best recommendations for the target users.</p>
      <p>The remaining part of the paper is organized as follows. Section 2 overviews
related work and defines the open problem and issues in the related research domain. In
Section 3, we define the research questions and present the research goal with
objectives. In Section 4, we describe the research methodology and the proposed approach.
Section 5 presents the current stage of our research and results achieved so far.
Finally, Section 6 concludes with plans for further research.</p>
    </sec>
    <sec id="sec-2">
      <title>2 Related Work</title>
      <p>Up to now, a number of approaches and techniques have been developed and
introduced for context modeling. Many studies show their benefits and applicability in
different application domains [1, 2]. In the following sub-sections 2.1 and 2.2, we
describe the most recent and used approaches for context modeling together with
context-aware frameworks for developing contextualized mobile applications.</p>
      <sec id="sec-2-1">
        <title>2.1 Context modeling approaches</title>
        <p>Recent used approaches to context modeling can be broadly classified into three main
categories.</p>
        <p>
          Multidimensional context modeling approach. This is one of the first
approaches proposed in [
          <xref ref-type="bibr" rid="ref3 ref4">3–5</xref>
          ] for generalized context modeling. The idea of this approach is to
make a decision to which context situation the entity is most relevant/similar. In this
approach, different context situations are represented as individual examples in
multidimensional space, and it classifies the entities based on their similarity to these
examples. Similarity is a decreasing function of their distance in a space [3]. Classical
examples of these models are the context space model (CSM) [
          <xref ref-type="bibr" rid="ref5">6</xref>
          ] and vector space
model (VSM) [
          <xref ref-type="bibr" rid="ref6">7</xref>
          ]. CSM uses the concepts from geometrical spaces: a context state and
a situation space. The context state refers to the current state of the entity being
modelled at a certain time based on the contextual information, and the situation space
represents a real-life situation based on a collection of context states during a certain
period of time. This modeling approach showed good practical usage examples in
developing context-aware mobile applications [
          <xref ref-type="bibr" rid="ref7 ref8">8, 9</xref>
          ], automatic anomalous human
behaviour detection [
          <xref ref-type="bibr" rid="ref5">6</xref>
          ], and Information Retrieval in context [
          <xref ref-type="bibr" rid="ref9">10</xref>
          ]. VSM measures the
similarities between the vector of the current context of an entity and the vectors of
different context situations that are represented in multidimensional vector space. This
approach is practically useful for modeling n-dimensions of context information and
finds similarity even when some context information is missing or not full.
Additionally, it has ability to represent the characteristics of the context at different levels of
detail. The more we know about the context of a situation, the better we can describe
user behaviour [2]. The main advantage of multidimensional approaches is a general
and unifying approach to model context for different application domains and enables
to match users’ context in real time.
        </p>
        <p>
          Object-role based models. This modeling approach was adopted from the
database modeling field [
          <xref ref-type="bibr" rid="ref10">11</xref>
          ]. Here, the context model language based on ORM was
developed to support object-role context modeling. Simple examples of such approach
are ContextUML [
          <xref ref-type="bibr" rid="ref11">12</xref>
          ], based on UML for development context–aware Web Services,
MLContext [
          <xref ref-type="bibr" rid="ref12">13</xref>
          ], based on Domain Specific Language (DSL) that provides high level
of abstraction and possibility to reuse context models in different application
domains.
        </p>
        <p>
          Ontology-based models. This approach has been widely used in modeling of
complex context situations. Using ontologies provides a uniform way for specifying
the model’s core concepts as well as an arbitrary amount of sub-concepts and facts,
altogether enabling contextual knowledge sharing and reuse in an ubiquitous
computing system [
          <xref ref-type="bibr" rid="ref13">14</xref>
          ]. This can lead to growing complexity for certain kind of applications
[1] Usually the mobile software developer does not have knowledge in Semantic Web
and ontology based principles and concepts. Since most of the existing
ontologybased models require some additional changes in the core model in order to adapt and
customize it for specific application domain, it reduces the practical applicability of
this models in mobile application development.
        </p>
        <p>
          The analyses of context modeling approaches and survey results [
          <xref ref-type="bibr" rid="ref14">15</xref>
          ] show that
there is not yet a common solution for a general context model and that the context
model should be chosen depending on the target application domain.
        </p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2 Frameworks for contextualized mobile application development</title>
        <p>
          During the literature review, we have found that most of existing frameworks provide
personalization rather then contextualization for mobile applications. The difference
between these two concepts is that personalization1 based on the user’s behaviour and
device/application usage provides recommendation to suit personal user preferences.
Examples of personalization can be offering services or products based on the user’s
search history, earlier purchase or favourite items (e.g., book author, movie director),
and adapting a user interface based on the user’s history of interactions with mobile
applications [
          <xref ref-type="bibr" rid="ref15">16</xref>
          ]. On the other hand, contextualization2 aims to utilize sensors and
technology to understand the current context of the user in order to better serve a
specific user need. In the literature, the six-layer enterprise framework architecture [
          <xref ref-type="bibr" rid="ref16">17</xref>
          ]
was proposed to support personalization and contextualization for mobile application
development. To the best of our knowledge, there is not yet a framework/SDK/Web
Service that can provide development of contextualized mobile applications.
        </p>
        <p>
          Based on the survey [
          <xref ref-type="bibr" rid="ref14">15</xref>
          ] of existing context-aware frameworks shows that the
mobile application developers should re-adapt the implemented context model to an
application domain or define a new context model. This reduces the usability of the
context models in practice of developing contextualized mobile applications.
        </p>
        <p>We propose an approach that uses the general concepts introduced in the
multidimensional approach for context modeling and use its flexibility to improve the
existing context models.</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3 Research Questions and Objectives</title>
      <p>
        Many researchers have been working on developing a general solution for context
modeling. However, a major problem with this kind of models is limited usability due
to their applicability for a specific application domain. Most of them require
additional changes in the core model that takes time, effort and knowledge of a framework
that can be time consuming for software developers. In the purpose of solving this
problem, we need to answer the following research questions:
- How can we model the context in a scenario independent way for mobile
applications?
- How can this context model be used/adapted for a specific mobile scenario?
- What kind of personalized features can be provided by the contextualization
approach in order to improve existing mobile services and applications?
Based on the research questions, the main and primarily objectives of our work are:
- to empirically investigate the modeling of different context data during the
context model design
- to develop a prototype to discover an abstract representation of the context
model
- to evaluate the proposed context model in several user studies in different
application domains
- to identify the contextualized features for mobile applications
1 https://www.techopedia.com/definition/14712/personalization
2 https://www.wordnik.com/words/contextualization
The primary research approach adopted to perform this work is based on the design
science research methodology (DSRM) proposed in [
        <xref ref-type="bibr" rid="ref17">18</xref>
        ]. This model showed good
practice in understanding and development of software applications. The
methodology consists of six main activities, which are iterated and shown in Fig. 1.
      </p>
      <p>The problem identification, motivation and definition of the objectives have been
described in the previous sections. The next sub-sections describe the details of each
activity and what was done in the first iteration. The current action is highlighted in
the Figure 1 and described in sub-section 4.1.</p>
      <sec id="sec-3-1">
        <title>4.1 Design and development</title>
        <p>This step consists of designing our approach for context modeling and building an
artifact of RCM. In the first iteration, the main objective was to define an approach
with certain abstraction for modeling and organizing the context information
independently from the scenario point of view. Here, we perform several actions shown in
Figure 2.</p>
        <p>
          We took as basis a multidimensional approach for context modeling and in
particularly the multi-dimensional vector space model (MVSM) [
          <xref ref-type="bibr" rid="ref18">19</xref>
          ]. In the first action we
defined which sources of context information should be used in our first prototype.
The defined sources are: mobile sensors and to extend this information, the Web
Service APIs (e.g., Google Places API, Weather API, Tomtom API, QRCodeReader
API) were used. After defining of Context Sources, we have analysed the data types
and data structures of these contextual information. The context data have different
data types (e.g., boolean, string, integer, float) and data structures (e.g., array of
hobbies), therefore our approach should know how to handle these data in an efficient
way. Based on the defined context data types and structures, we identified the
primary data processing algorithms that are a combination of different similarity metrics
(e.g., Jaccard distance for Boolean values, Euclidean distance for numerical values).
The output of the defined algorithms is an input for the Suggestion Making action,
where we provided an approach that makes a suggestion based on the outputs of data
processing algorithms. Here, first we did scaling and normalization of values and used
cosine distance to measure similarity.
        </p>
        <p>After each performed study, the first three actions are iterated to improve the
context model (e.g., make it more abstract, add/replace data processing algorithms) that
should lead to providing better suggestions/recommendation results.</p>
      </sec>
      <sec id="sec-3-2">
        <title>4.2 Demonstration and evaluation</title>
        <p>
          In the first iteration, the first prototype was developed using the jQueryMobile
framework with the Cordova API for mobile application and the NodeJs framework
for implementing our contextualization approach. To demonstrate and test the
prototype, we performed two studies in mobile learning and people-to-people
recommendation domains. The obtained results were published in two scientific conferences
[
          <xref ref-type="bibr" rid="ref19 ref20">20, 21</xref>
          ], and proved the possibility to reuse the context model in various application
domains.
        </p>
        <p>
          The evaluation is carried out using adopted TAM questionnaires in particularly
Perceived Usefulness and Perceived Ease of Use. In the first study [
          <xref ref-type="bibr" rid="ref19">20</xref>
          ] we
investigated the potential benefits of using the contextualization approach for mobile
application compared to an ordinary (without contextualization) mobile application and its
usability. In the second study [
          <xref ref-type="bibr" rid="ref20">21</xref>
          ], we investigated the flexibility of our
contextualization approach in terms of handling different data types and priorities of contextual
information.
        </p>
        <p>Currently, we are developing a second prototype of our contextualization
approach. Here, firstly we went through Design and Development action to apply new
changes that were defined after the first two studies. Secondly, we target to deploy the
second prototype as a service in the cloud environment and evaluate it in several
application domains.</p>
        <p>
          The validation of proposed RCM is carried out using defined metrics and
characteristics introduced in study [
          <xref ref-type="bibr" rid="ref14">15</xref>
          ].
        </p>
      </sec>
      <sec id="sec-3-3">
        <title>4.4 Communication</title>
        <p>
          The identified problem and the proposed artifact are communicated to researches
through several publications at conferences. Our first paper was published at mLearn
conference [
          <xref ref-type="bibr" rid="ref18">19</xref>
          ], in which we described the mathematical foundation of our approach.
In the second paper, published at ICCE 2014 [
          <xref ref-type="bibr" rid="ref19">20</xref>
          ], we defined the benefits of using
our contextualized approach for m-learning applications. In the following paper [
          <xref ref-type="bibr" rid="ref20">21</xref>
          ],
we defined an approach of handling different data types and priorities of contextual
information. Two book chapters on the same research domain are under press status
[
          <xref ref-type="bibr" rid="ref21 ref22">22, 23</xref>
          ]. In the first book chapter [
          <xref ref-type="bibr" rid="ref21">22</xref>
          ], we discussed the contextualization of mobile
learners, and in [
          <xref ref-type="bibr" rid="ref22">23</xref>
          ] we discuss the benefits of using cloud-based mobile applications
in the m-learning domain and propose the flexible and contextualized service to
support contextualization in m-learning applications. As this is work in progress, we aim
to publish a journal paper to communicate the new results that will be obtained from
the second prototype.
        </p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>5 Potential Contributions</title>
      <p>The main contribution of this research work is an approach for the development of
contextualized mobile applications. In contrast to the existing approaches, our
approach has flexibility gained through an abstract context model that could be applied
to different application domains without the need for a change in the core context
model. Our approach suggests a new contextualization service that provides
possibility to develop highly personalized mobile applications. With the employment of our
approach, mobile software developers will be able to easily develop contextualized
mobile applications for their target users and may raise the number of satisfied users
hopefully leading to the increase number of potential users.</p>
    </sec>
    <sec id="sec-5">
      <title>6 Future Work</title>
      <p>Further research will be more focusing on defining the features that our
contextualization approach can provide. It will include analyses of already existing contextualized
features of personalized mobile apps in the market place, gathering main requirements
for developing personalized mobile apps from several mobile software developers, the
development of Contextualization Service, evaluation in different application
domains, and validation. This plan will help to answer the second and third research
question of this work. The expected results are the classification of features and
potentially of creating customized mobile app features for different application domains
and users.</p>
    </sec>
  </body>
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