Distant learning is developing and attracting more users due to the availability and popularity of computers and mobile devices among young and old learners alike. A lot of learning platforms provide courses and training in different fields, but lack accessibility for the visually disabled students, and cannot be optimally accessed from a handheld device, whereas mobile devices are very popular.

1. A MODEL DRIVEN ACCESSIBLE M-LEARNING
PLATFORM
Majdi Soufi 1
, Nizar Mejdoub 1
, Amina Bouraoui 1,2*
1
UR Evaluation et Santé, Faculté de Médecine, 15 rue Djebel Akhdhar - La Rabta - 1007 Tunis,
Tunisia
2
Institut Supérieur des Technologies Médicales, 9 Bd Dr Zouheir Safi-1006 Tunis, Tunisia
2
email : hannibal.a@topnet.tn; phone : +21698200097
ABSTRACT
Distant learning is developing and attracting more users due to the availability and popularity
of computers and mobile devices among young and old learners alike. A lot of learning
platforms provide courses and training in different fields, but lack accessibility for the
visually disabled students, and cannot be optimally accessed from a handheld device, whereas
mobile devices are very popular.
Therefore, we developed a new learning platform accessible from a desktop/laptop computer,
or a wireless/handheld (W/H) device. To facilitate access for the visually disabled users we
developed a speech synthesis web service.
KEYWORDS: model driven engineering, mobile learning, accessibility
INTRODUCTION
The project consists in three independent parts:
− A platform allowing students to connect via their mobile equipment, study, review courses
content, answer their messages, answer quizzes, ...etc. Each student evolves inside a
community of teachers, tutors and fellow students. The platform can be accessed from a
desktop, a laptop computer and from a W/H device. Plasticity allows the interface to adapt
automatically to the used device;
− An editor of accessible mobile content which creates courses in accordance with the W3C
recommendations for accessible web content and mobile content which respect the
WCAG1.0 accessibility standard, and the e-learning standards we adapted to m-learning.
The courses and quizzes are designed very simply, indeed a W/H device must not be
overloaded with information;

2. − The third part of the project consists in a screen reader web service that allows the learner
to have his page contents read.
Before describing each part of the project in the following paragraphs, we will start by
presenting the model driven engineering approach we used for conceptual purposes.
CONCEPTUAL MODELING
The model driven approach
We used a model driven methodology for our work to facilitate the generation of code which
can be maintained and modified easily, when a new technology, platform, or standards
appear. We based our work on the Model Driven Architecture proposed by the OMG [1]. This
approach encourages separation of concerns between system functionalities and
implementation technologies. High level models describe the system functionalities: the
learning platform, the pedagogical mobile content, the speech synthesis, the web service, and
the accessibility features. These models are thereafter transformed using conversion rules to
obtain the target platforms specific models. Finally these latter models are used to generate
the system source code.
There are three basic concepts in the MDA (Model Driven Architecture) approach: meta-
models, models and transformation engines.
Meta-models and models
Meta-models are used to furnish the basic concepts that will be used to describe models. The
OMG encourages the use of MOF (Meta Object Facility) [2] meta-language to create meta-
models.
Models are used to describe the system functionalities whether they are high level
descriptions or low level technical descriptions, UML models can be used at this level based
on the UML meta-model described in MOF.
There are three types of models in the MDA approach:
- the Computation Independent Model (CIM): describes the application specification and
requirements. UML use cases can be used for this model;
- the Platform Independent Model (PIM): describes the system domain concepts without
considering any platform details, UML diagrams can also be used in this part;
- the Platform Specific Model (PSM): describes the platform for which the system will be
implemented, this model can also be a UML diagram conform to a UML profile; the PSM is
converted to the system source code for the targeted platform such as Java, .Net,...etc.
Transformation engines
They are based on corresponding rules between meta-models defined manually by an expert
user, they are used to transform a model to another, or a model to source code. For example a

3. PIM can be converted to a PSM, a PSM to another PSM, a PSM to a PIM (in case of a reverse
engineering process), or a PSM to Java code. Matching rules are proposed and the
transformation from a PIM to a PSM for instance is based on these rules and executed
automatically by a transformation engine (a program which applies the transformation
between model concepts). The OMG encourages the use of QVT (Query View
Transformation) [3] standard to write transformations.
As models in the MDA approach have to be compliant with meta-models, the matching rules
for the mapping model are based on matching correspondences between the meta-models
concepts.
The transformation can be automated for better results, for example if we find a way to
specify matching rules automatically instead of manually this will lead to better and faster
results [4,5]. But we cannot prevent the user from interfering in the matching process, and this
makes it more reliable. For this purpose we are studying the matching techniques in the field
of model driven engineering [4, 5].
The advantages of this approach are the following:
- The platform independent model can be modified each time we want to modify the system
functionalities. Starting from a single PIM we can obtain by transformation different PSMs
for different target platforms;
- The platform specific model can be converted to many targeted platforms if we are able to
define technical details of these platforms inside models, or each time a new platform
emerges;
- The sustainability of specification models, and the possibility to reuse existing models.
THE LEARNING PLATFORM
We have designed a learning platform that allows teachers and students to access courses and
quizzes and share them with each other. The students can access the platform via a PC or a
mobile phone connected to the Internet, they can choose courses, answer quizzes regardless of
where they are. The students and teachers evolve inside a community of friends who can be
either teachers, tutors or students.
We based our idea on popular social networks that are very appreciated by large and different
communities.
Each registered member has a profile page with basic info and activities. A member can have
friends inside a community, and can follow their activities.
The platform functionalities
The first goal of the platform is the connection of registered members for learning objectives.
Besides the users can also send emails, generate PDF files for the available courses or
quizzes, search for friends, look at the recent activities and feeds shared by the community,

4. search for lessons or activities using keywords,...etc. All these functionalities are offered
inside a simple interface with the most important feeds in the home page (Fig.1).
Figure 1 - The platform home page on Mobile device and PC
Design principles
-Simplicity: the interface is not overloaded with extra information, which makes it light and
easily mastered by users with different skills, and also easily accessible form a W/H device.
Indeed we have to consider the different mobile limitations such as screen sizes, memory and
CPU capacities, connection limitations ...etc.
-Accessibility: the platform is designed with accessibility features; we applied the W3C
standards in order to make it accessible to different categories of users using a
PC/Laptop/W/H device. For this reason we adapted both guidelines for mobile development
[6, 7] and standards for accessibility using the WCAG [8] and ATAG guidelines [9].
-Plasticity: the platform is accessible via computers or W/H mobile devices. Indeed when
connecting using a mobile device, the platform automatically adapts its interface to fit the
mobile characteristics, such as the screen size. We use the “user-agent” component of the
browser which indicates if the user connects via a PC or another device. In this latter case, we
have to know which kind of mobile it is. We ask the WURFL API [10] to know the device
capacities (size, technology...etc.). Thereafter we use WALL [11] which provides different
mobile technologies adapted to the device capabilities. Figure 2 illustrates the plasticity
principle and the technologies involved.

5. -Security: to minimize the risk of hacking we use scripting to avoid attacks of the type XSS
and SQL injection and the protocol HTTPS and SSL to exchange data between the user and
the web server.
Figure 2 - The plasticity principle illustrated
THE CONTENT EDITOR
We give the opportunity to teachers to create lessons and quizzes online or offline using two
kinds of content editors.
The platform provides an integrated WYSIWYG editor to edit web pages which offers the
classic functions of word processors. Its two main advantages are ease of use and immediate
observation of the graphics rendering. This editor prevents from the use of an external content
editor, and is based on Ckeditor a free and open source application which supports WAA-AA
and WCAG 1.0 accessibility standard. This tool is fully keyboard navigable and can be used
with screen readers (Fig.3).
With this tool every teacher can create a course and publish it directly in his/her network. The
courses are designed as a collection of chapters; the teacher can create, edit, modify, and
delete a chapter. The editor checks the accessibility standards of W3C in real time. For
instance, if the teacher omits to give an alternative text for a figure or a table, the content
editor will warn her/him.
The teacher also has a quiz generator to create evaluation tests for students. The quizzes have
general information and questions/answers saved as XML documents into the database.

6. Figure 3 - An example of lesson creation using the platform integrated editor
An independent content editor is now being developed to provide a second alternative for
teachers who want to have more options and use a more sophisticated tool to create their
courses and activities. This editor must be used offline or online from a computer. It is not
light enough to be accessed from a W/H device and its functionalities are numerous and
complex for a mobile use. We adapted e-learning norms and standards to m-learning. The
courses and activities are created for mobile purposes to improve the user experience of
usability. The pedagogic contents are accessible to be read by the text to speech web service.
THE SCREEN READER
Access to mobile devices can be a challenge for visually handicapped users. Designing an
application with accessibility features is not sufficient to guarantee the access from a mobile
device due to the lack of assistive technologies for this kind of devices. In case the user
connects from a PC or a laptop he/she has to be able to access the content using assistive
technologies. In the case the user logs in using a mobile device this can be more difficult to
achieve.
Developing a text to speech web service is an added value for our work. Web services are
applications accessible from the Internet. The web service will act as a screen reader or a text
to speech browser. The user presses a phone key; this will send a text message to the web
server containing the web service. The web service will split the text in syllables and convert
each one to audio form. The next step is to merge the audio files into a single one and send it
back to the source (Fig.4).

7. Figure 4- Illustration of the TTS web service process
The conceptual part of this work is detailed hereafter: we designed the text to speech and the
web service meta-models compliant with the UML meta-model. The two meta-models are
used to describe two PIMs, which are merged to describe a single PIM [12] of text to speech
web service. This latter is converted to a target platform (PSM), for instance Java, as the
majority of mobile devices are based on Java environments. The Java Profile is used as a
meta-model for the target platform PSM.
CONCLUSION
In this paper we have presented our work consisting in studying and developing a new m-
learning platform accessible for visually handicapped users. The work has been developed in
three independent parts, an m-learning platform, a content editor of accessible courses and
activities and a French text to speech web service. It will be used by the Virtual University of
Tunis for registered members (students and teachers/tutors) to encourage mobile learning.
The conceptual part of our work is based on model driven engineering, which facilitates the
separation of concerns and guarantees abstract models that are modified only if functionalities
evolve. Target platforms for code generation can be added when needed, so we can respond to
the great variety of mobile operating systems without developing a new application each time.
Our goal is to provide an accessible Learning and Content Management System especially
dedicated for mobile or W/H equipment use. The perspectives of this work are numerous:
- improvements of the speech web service, for example we have to consider multilingual
aspect for language learning; in the future we would also like to use this web service to read
any information on the mobile device;

8. - we want to consider difficulties encountered by a large number of users to maintain a
constant or a free connection to the Internet. With the actual platform, users can generate PDF
files of lessons. In the future we want a lightweight version of the platform to be
downloadable to act as a client side application [13], without the obligation of an Internet
connection;
- automation of the correspondences rules between models for faster and better results and to
facilitate the source code generation process for different platforms and operating systems.
- in the near future we plan to conduct tests with students enrolled in the Virtual University of
Tunis.
ACKNOWLEDGEMENT
Authors would like to thank the Virtual University of Tunis (UVT) and its president Pr
Houcine Chebli for his support.
REFERENCES
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[3] OMG, QVT 2.0 Transformation Spec., http://www.omg.org/spec/QVT/1.0/PDF/, April
2008
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