A Model Driven Approach for Improving the Generation of
Accessible User Interfaces
Lamia Zouhaier, Yousra Bendaly Hlaoui and Leila Jemni Ben Ayed
Laboratory LaTICE, Higher School of Sciences and Technologies of Tunis, University of Tunis, Tunis, Tunisia
Keywords: Accessibility, Disability, Modality, Adaptation Process, MDE, Transformation Pim2pim, User Interface.
Abstract: In a ubiquitous computing, disable users are required to accommodate their particular needs using interactive
systems. Thus, ensuring accessibility into applications' user interfaces is highly recommended. Hence, it is
crucial to elaborate a generic solution which is compliant to handicapped user requirements. Therefore, this
paper is addressed to define a model driven approach for generating adapted interface according to
accessibility context. This approach benefits from Model Driven Engineering methodologies. In addition, it
is characterized by the integration of a multimodal solution which selects the suitable modality of interaction
into the adaptation process. This will improve the degree of user interface flexibility. This approach is based
on different model transformations’ belonging to different abstraction levels of the adapted user interface
development according to the captured accessibility context attributes.
1 INTRODUCTION
Technological change delivers products and services
requiring particular skills and abilities of the users.
Traditional user interface engineering doesn't address
disable users requirement when developing
interactive systems. This implies the indispensability
of pushing this type of interface from traditional to
modern adaptive user interface. Hence, interactive
systems must to be flexible and autonomous in order
to match the big numbers of users’ requirements and
preferences (Lopez, 2003) but also the diversity of
computing devices (mobile phones, PDAs, PC,
interactive kiosks, etc.). Unfortunately, users with
special needs (hearing disabilities, sight disabilities,
physical disabilities, cognitive disabilities, etc.) are
confronted to a big numbers of access barriers when
interacting with user interfaces using emerged
devices. It is indispensable to define a generic
solution for this category of users that guarantees an
equal access and an a good quality of life.
In this paper, we propose to address this problem
by a generic solution for developing accessible user
interfaces applications based on Model Driven
Engineering. Model Driven development approach
has benefits in developing multiple variants of a UI
for multiple target platforms, devices, users, or
situations developed from the same abstract UI
models. It has the advantage of transforming high
level specifications into executable code. An Abstract
UI (AUI) is transformed into a Concrete UI (CUI),
followed by the Final UI.
This approach aims to provide an infrastructure of
automatic adaptation and generation of user
interfaces based on user interface model and
accessibility context. It allows the specification of the
interaction modality by constructing and
manipulating the abstract components of PIM model
according to user disability.
Therefore, our approach is based on three levels:
- In the first level, we proceed by modelling the
application interfaces, and the captured
accessibility context. The provided models are
platform independent (PIM) specified
accordingly to a metamodel that we have already
defined. This metamodel describes our UML
profile language specific to define user interface.
- In the second level, we apply the adaptation
process by means of different transformations.
Once the PIM is adapted, its transformed to
specific platform model accordingly to the
defined technical and environment contexts
- In the third level, the provided PSM will be
transformed to concrete model relative to the
targeted device.
This approach improves the system’s capacity to
manage the accessibility context inside the adaptation
168
Zouhaier L., Hlaoui Y. and Ayed L..
A Model Driven Approach for Improving the Generation of Accessible User Interfaces.
DOI: 10.5220/0005559601680173
In Proceedings of the 10th International Conference on Software Paradigm Trends (ICSOFT-PT-2015), pages 168-173
ISBN: 978-989-758-115-1
Copyright
c
2015 SCITEPRESS (Science and Technology Publications, Lda.)
process at the runtime and to generate the adapted
interface model using multimodal interaction.
Model based approach is a feasible solution for
addressing accessibility into applications. In fact, it
identifies useful abstractions highlighting the main
aspects that should be considered when designing
accessible application.
Model Driven engineering MDE is a development
approach which puts emphasis on models. It provide
a good practices of UI generation. The approach
define UI models of high abstraction from which UI
models of lower abstraction are obtained successively
through model to model transformations and model to
code transformation (Aquino, 2010). These
transformations are made automatically. Using
Model Driven Engineering, we guarantee the
efficiency and consistency when developing multiple
variants of a UIs from the same abstract models.
Based on a parameterized MDA-transformation,
we propose an adaptation approach dependent on
accessibility context presented in a previous work
(Zouhaier, 2013). The approach extends and
generalizes the process in (Zouhaier, 2014).
This paper is addressed to propose a generic
solution for developing accessible user interfaces
applications based on MDA paradigm (OMG, 2001).
The proposed solution includes a set of parameters
that is based on:
- Accessibility context-aware process followed by
a context modelling to define disabled user
profile, its suitable modality and the device mean
characteristics.
- A set of assistive technologies that must
accomplish the User Interfaces design as Speech
Recognition and Synthesizer in the case of vocal
User Interface.
- A set of accessibility guidelines to generate rules
for user interface adaptation process,
- A set of parameterized model transformations to
generate automatically adapted and specific user
interface models.
In fact, the proposed approach has to be characterized
by its capacity of context-awareness. It must to be
able to capture and manage all contextual information
related to user, platform, and environment, location
and time. Therefore, based on the given disabled user
context model, it has to perform the adaptation at
runtime depending on different situations. Thus, it
selects the best adaptation rules for the suitable
interaction modalities according to the disable user.
This will improve the degree of user interface
flexibility.
The remainder of this paper is as follows: in sec-
tion 2, we present some relevant work in relation with
our problematic. The section 3 details our approach
by presenting their steps, and user interface models.
Finally, section 4 concludes the paper and presents
our future research.
2 RELATED WORK
This section is related to existing relevant works
related to different proposed approaches devoted to:
accessibility approach, Adaptive UI approach, Model
based UI approach.
The development of accessible applications must
meet specific guidelines for accessibility. We note
that multiple standards and guidelines have been
emerged recently such as WCAG 2.0 (ISO, 2012),
(Henry, 2012) and ISO9241-171 (ISO, 2008).
However, fulfilling such guidelines is not sufficient,
it still a little solution for accessibility problems.
Regarding accessibility, many works had
considered primarily only the field of Assistive
Technology (AT) (Stephandis, 1998). Example, when
navigating via screen reader, the user perceives page
content in a very different way from its rendering on
the screen.
Therefore, the accessibility is considered as
prescribed requirements for the use of a product by
people with disabilities (Stephandis, 2001) (Arrue,
2007).
Few works have been focused on identifying
generic solutions adapting user interfaces to various
combinations of contexts of use (Thevenin, 1999)
(Calvary, 2002) (Bacha, 2011) (Bontagartz, 2012)
(Minon, 2013). Specially, adaptations which are
based on context-awareness mechanisms specifying
disabled people (Stephanidis, 1998) (Akoumianakis,
1999) (Lopez, 2003) (Abscal, 2011) (Peißner, 2012)
(Manca, 2013). Many focus on context capture (Dey,
2000) and adaptation (Calvary, 2002) (Thevenin,
1999) by the use of legacy architectures and others
artifacts to input context into application logic (Vale,
2008).
Few works have been focused on identifying
generic solutions adapting user interfaces to various
combinations of contexts of use (Calvary, 2002)
(Bacha, 2011) (Bontagartz, 2012) (Minon, 2013).
Some other works (Bouchelliga, 2010) (Brossard,
2011), (Bacha, 2011) (Oliveira, 2013) propose
solutions based on model based approach. They use
MDA as a standard on context-aware development
and adaptation of a UI.
Bouchelliga et al., (Bouchelliga, 2010) have
proposed a MDE approach for plastic HCI. UI
AModelDrivenApproachforImprovingtheGenerationofAccessibleUserInterfaces
169
adaptation considers various aspects of context and it
is based on parameterized transformation. The
authors provide the meta-models of the different
contexts used in the approach to adapt the interface.
Adaptation is made during the design and treats as
aspects of the dimension of presentation with
container and not the contents.
However, none of these studies have considered
accessibility context into adaptation process using
model based development basically the MDA
approach.
Sottet et al., (Sottet, 2005) have joined his work to
the Model Driven Engineering and the domain of
Human Computer Interaction (HCI). His approach
makes it possible to show that the concepts of the
MDE could be successfully applied to the UI
engineering. Sottet et al. proposes meta-models and
models transformations to generate adaptable UI, and
defines a general context meta-model based on
CAMELEON platform (Calvary, 2003). In fact, he
has been based on CAMELEON languages to
describe his models. Unfortunately, the CAMELEON
do not allow adaptation based on the description of
accessibility context. There is why we are brought by
defining our UML profile languages specific to define
user interface models accordingly to accessibility
context.
Based on this state of the art, we are able to
approve our main objective which is basically
ensuring accessibility of user interfaces for people
with disabilities. We can say that there are few
research proposals that have considered accessibility
context into conceptual design of UI in adaptation
process at runtime. But also, few works are based on
a model-based method using the Model Driven
Engineering (MDE) (OMG, 2001) approach for
adaptation according to accessibility context.
3 OUR PROPOSAL MODEL
DRIVEN APPROACH
Model based approach is a feasible solution for
addressing accessibility into applications. In fact, it
identifies useful abstractions highlighting the main
aspects that should be considered when designing
accessible application. Based on a parameterized
MDA-transformation, we propose an adaptation
approach dependent on accessibility context as
presented in another work (Zouhaier, 2013). We
follows the CAMELEON Framework (Calvary,
2003) to provide an overview of the mapping from
actual context to a specific accessibility context. As
described in the figure 1, the approach is basically a
series of transformations from application model to
final adapted application. As indicated, a reverse
PIM. Secondly a transition in the abstract level from
PIM A to PIM B in order to generate an adapted
Abstract User Interface specific to the accessibility
context. Finally, an parameterized MDA
transformations is applied to generate final interface.
Figure 1: The mapping from actual context of user to target
accessibility context using the CAMELEON Framework
(Calvary et al., 2003).
This approach aims to provide an infrastructure of
automatic adaptation and generation of user
interfaces based on application’s user interface model
and model accessibility context development. Figure
2 illustrates the approach steps:
1. Step 1: first, we provide an abstract view of the
user interface using our UML profile specific to
describe user interface models. UI model is in
conjunction with two others model which are Data
Model and the External Functions Model. These
models describes the The abstract view represents a
non adapted Platform Independent Model (PIM A).
Then, we collect all information relative to the
accessibility context to build actual accessibility
context model. We use an ontology model in order to
manage high-level context properties acquired from
sensors related to environment, platform and user.
2. Step 2: the adaptation process transforms the
interface model (PIM A), provided by the first step to
an adapted interface model (PIM B). This process is
based on the ontology model provided by the first step
of the approach and adaptation rules depicted from
the WCAG2.0 and ISO 9241-171 guidelines.
3. Step 3: using the adapted model, which represents
the output of the adaptation process, we generate the
Platform Specific Model of the adapted UI (PSM) and
then the relative code, depending of application
platform, using simultaneously PIM2PSM and
PSM2Code transformations.
ICSOFT-PT2015-10thInternationalConferenceonSoftwareParadigmTrends
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Figure 2: The proposed Approach with the incorporation of
multimodality solution.
According to user disability, different interaction
modalities are required. Therefore, we propose a
multimodal approach by incorporation of the
modality of interaction into adaptation process. It
permits to the system to provide the best modality for
accessibility context according to user‘s disability.
Incorporating flexibility to choose desirable modality
into user interface systems is indispensable for people
with disabilities, since most computing applications
use graphical modality into user interfaces useful only
to sighted users.
This approach must enable to trigger the best from
several alternative interaction modalities to fit the
best adapted model.
Based on a work given by (Aquino, 2010) where
the authors describe a framework of different type of
transformations coping with the development of UIs
for single and multiple contexts of use, we propose
according to the two proposed viewpoints on UI
systems:
- Platform-independent viewpoint contains a
viewpoint that is (1) independent of the
computing platform for which the system will be
implemented and (2) dependent of a particular
modality.
- An implementation viewpoint is a viewpoint
containing a coded UI i.e., any UI running on a
particular platform.
3.1 PIM Metamodel/Abstract User
Interface Description
Abstract User Interface Model or Platform Indepen-
dent Model is an independent model of any
interaction modality and computing platform. It
doesn’t give any abstract specification how the
interface will be concretized: graphical, vocal or
multimodal. In literature, it is described by different
manners. In literature, we find that different definition
was given with different annotations. But, they differs
by the designation used to refer each element of the
user interface model.
In our approach, we have described the user
interface model by an association between different
components that are related to the modality used.
Hence, the transformation from PIM2PIM to adapted
PIM is a remodelling of the user interface model
using the disability parameter by switching the actual
interaction modality into the suitable modality. At
this level, the PIM will take into account the new
modality and make the best transformation at layout
and presentation units. This transformation of UI
structure is dependent of the value of disability. In
some case, some abstract components must be placed
into separate containers.
In our approach, we define the PIM model as a
composite of a set of an abstract user interface
element (AUI Element) that are clustered into a set of
an abstract containers (Container Element) connected
by UI relationships (Relationship Connection). AUI
Element represent the elementary component of the
interface which can be Input Element, Output
Element, Control Element, Navigation Element.
Container Element which regroups a set of UI
Element, is described by it type and the corresponding
layout. Each PIM corresponds to one or many
modalities of interaction.
4 CONCLUSION AND FUTURE
WORK
In this paper, we have proposed a model driven
approach for adapting application‘s user interface to
the context of accessibility. This approach proposes
different transformations at different levels of
abstraction to generate adapted user interface. We
have focused on PIM 2PIM transformation which
presents the core of the adaptation process.
Actually, we are working on developing a tool
supporting our approach by implementing different
transformation processes. The PIM 2PSM
transformation is implemented using the ATL
transformation, language (Eclipse, 2014).
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171
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