Authores: Lourdes Moreno, Paloma Martínez, Belén Ruiz-Mezcua IWWOST 2008: 7th International Workshop on Web-Oriented Software Technologies, in conjuntion the 8th International Conference on Web Engineering (ICWE'2008) (July 2008, Yorktown Heights, New York, USA). A MDD approach for modelling web accessibility,

1. Lourdes Moreno, IWWOST, NY, USA, July 2008
"A MDD approach for modelling web
accessibility“
Lourdes Moreno, Paloma Martínez, Belén Ruiz
LABDA Group, Computer science department

2. Lourdes Moreno, Yorktown Heights, NY, USA, July 2008
What is the web accessibility?
Some web accessibility problems on the web:
If the size font is small, and the user wants to become it bigger.
=> He doesn’t read, the readability of the text is lost

3. Lourdes Moreno, Yorktown Heights, NY, USA, July 2008
What is the web accessibility?
Some web accessibility problems on the web:
• If we use a device that it do not activate the JavaScript, or one user
access to web with special browser, screen reader, …
=> we cannot access to several hypermedia elements.

4. Lourdes Moreno, Yorktown Heights, NY, USA, July 2008
What is the web accessibility?
Some web accessibility problems on the web:
• If we use a only text browser, or we have a low speed connection, or one user
access with an screen reader
=> we do not understand the contents, because the images have not an alternative
text and important information can not be accessed.

5. Lourdes Moreno, Yorktown Heights, NY, USA, July 2008
What is the web accessibility?
Some web accessibility problems:
• I need access to one web with a device such as a mobile, PDA, etc, but I cannot
to access.
Error with Sony
Ericsson K750
Error with Nokia N70
Error with
iPhone 3G

6. Lourdes Moreno, Yorktown Heights, NY, USA, July 2008
What is the web accessibility?
Some web accessibility problems:
• The same web page can be different”, if we access to web page with
Internet explorer, or Firefox, or Opera, etc.
=> perhaps , we do not access to some web contents of web page
Do not access to tool bar
Internet Explorer view
Firefox view

7. Lourdes Moreno, IWWOST, NY, USA, July 2008
Introduction
• The web offers many services, but these are not accessible to all.
• The users with the biggest problems are those with disabilities, but
accessibility barriers affect a wider range of users and usage contexts.
=> Web access should be available to any person, regardless of how one
may access it.
• Accessibility does not entail higher costs and problems. Web
accessibility has many benefits, such as easier maintenance, scalability,
better positioning in search engines, multidevice Web applications, etc.
• Accessible design is simply good design.
• Accessible development implies some difficulties: lack of cost previsions
and which method to follow to include accessibility criteria in the process.

8. Lourdes Moreno, IWWOST, NY, USA, July 2008
Related work
• When considering accessibility in the development process, technological,
human and legislative aspects must be taken into account, and because of this,
related work from numerous disciplines have been considered.
– In some countries, legislation about web accessibility.
– Standardization: Web Accessibility Initiative (WAI) => The Web Content
Accessibility Guidelines (WCAG).
• Accessibility evaluation, definition of metrics, etc.
– Human-Computer Interaction (HCI). Relationship between usability and
accessibility, User Centred Design (UCD) methodologies.
– Software engineering.
– Web engineering.
– Web semantic technologies: such as XML, ontology, etc.
=> However, accessibility criteria do not cover the whole life cycle, nor they are
fully integrated in the development process. There is also a lack of support
for designers.
• This work is the basis of a thesis, Accessibility for Web Applications (AWA). Its
objective is to offer methodological support to integrate accessibility, from a Web
engineering perspective, in the whole life cycle of a web application.

9. Lourdes Moreno, IWWOST, NY, USA, July 2008
AWA: Accessibility for Web Applications
Baseline
• Based on various disciplines:
– Web engineering which provides specific modelling techniques as well as
development processes.
– Traditional software engineering to provide methodological support to the
development and the project management team.
– Accessibility and usability aspects from HCI discipline.
• A User-Centred Approach:
Engineering approaches are centred on the architecture - there is a distance
from the user.
=> AWA follow an inclusive User Centered Design (UCD), with the use of
usability techniques originating from HCI discipline.
• Integration in different methodologies:
The development of accessible web applications does not require a specific
methodology in itself; this only makes sense when the methodological
approach includes accessibility criteria.
=> Integration in different methods

10. Lourdes Moreno, IWWOST, NY, USA, July 2008
AWA: Accessibility for Web Applications (2)
Baseline
• Compliance with standards:
– On the web: W3C (WCAG, XHTML, CSS, ...)
– Design and development processes: Management Group standards
(OMG), Unified Modelling Language (UML),..
• Web accessibility is more than the WCAG:
– The WCAG standard not only needs to be understood, but also
needs to be globally considered:
• To elicit the requirements in order to identify other accessibility
requirements.
• To include aspects of modelling accessibility.
• To include plans and management of accessibility.
• When new technologies become available:
– Web 2.0: the users are designers, creators.
– New devices.
– Web interfaces to improve the user's experience such as RIA.

11. Lourdes Moreno, IWWOST, NY, USA, July 2008
• In current developments it is usual to find accessibility considered only as a non-
functional requirement of the WCAG standard.
• This approach to accessibility should be changed. => the accessibility framework
in the development process also entails functional and quality requirements in the
whole process.
• Following the WCAG standard in the whole process.
• Usability, user-centered design.
• Mechanisms to safeguard accessibility throughout the life cycle of web
applications.
• Management of accessibility during the process. Monitoring.
• System management of complaints from users.
• Components affected by accessibility directly or indirectly during the development
process are detected in the whole life cycle of the application.
• The aim is to detect and avoid resulting accessibility problems which these
affected components may cause and to define and prepare Accessibility
mechanisms.
AWA: Accessibility for Web Applications
Strategy: Accessibility requirements

12. Lourdes Moreno, IWWOST, NY, USA, July 2008
A MDD approach for modelling web accessibility
Accessibility mechanisms and MDA process (2)
– Domain specific metamodel.
– To extend the models.
– Transformation: model2model,
model2text.
– Generation of the final Web code.
– etc.
• If the different kinds of requirements are considered, there are several
accessibility mechanisms.
• In MDA development process, there are different components affected. The
accessibility mechanisms have to be included in the different application points in
the process:
The concept image have been defined
at the metamodel MOF that includes
required attributes to comply the
standard WCAG, and may be included in the PIM models, which contain the
knowledge included necessary for the web code generation in the final phase

13. Lourdes Moreno, IWWOST, NY, USA, July 2008
• To integrate accessibility mechanisms into the Model development
process, web engineering methodologies have been followed.
• With the use of the abstraction mechanisms of the Model Driven
Development (MDD) including its accessibility requirements.
– The process must be iterative, guided by continuous evaluation and tested
by users.
⇒ To use the modelling techniques of Web engineering methods, based on
the Model Driven Architecture (MDA) development process.
The objective is to be able to use any method rather than a specific one, to
be able to include accessibility aspects in the models of the method
concerned.
A MDD approach for modelling web accessibility

14. Lourdes Moreno, IWWOST, NY, USA, July 2008
A MDD approach for modelling web accessibility
Accessibility mechanisms at the metamodel
• In this first approach, a
domain-specific metamodel
for Web accessibility has
been offered.
• At the metamodel level, the
accessibility mechanisms
have been included
• Concepts and their
relationships of standard
accessibility in the WCAG 1.0
current version and the
WCAG 2.0 next version have
been modeled.

15. Lourdes Moreno, IWWOST, NY, USA, July 2008
• This knowledge into a domain model serves as a bridge for the web
application analyst and designer, modelling and describing the
accessibility requirements and how to use them later in the system.
• The purpose is to encapsulate accessibility aspects in the whole
development cycle.
• EMF (Eclipse Modelling Framework) with Ecore language has been
used.
• The research is continuing to validate the viability and application in
different methods. The following results have been obtained:
 The level of abstraction of the standard concepts needs to be raised
to avoid dependence on accessibility standard, and some concept
are not a specific language.
 Some concepts modeled at the metamodel level will pass to the
model level.
A MDD approach for modelling web accessibility
Accessibility mechanisms at the metamodel (2)

16. Lourdes Moreno, IWWOST, NY, USA, July 2008
• According to research that has been carried out on the application of the
accessibility mechanisms, a dependence on the method has been observed.
• The strategy is to establish common accessibility criteria for all methods and
determine the specific mechanisms for each method.
• Case study: OOWS Method with MDA process.
(research in progress, preliminary findings)
To give an example of how to include accessibility requirements (guidelines WCAG)
within an abstraction level based on the MDA in OOWS Method:
– Compliance with some guidelines according to WCAG standard
• Guideline 1.2
• Guideline 1.3
How are accessibility mechanisms articulated in the OOWS Method?
AWA: Accessibility for Web Applications
Case study in specific method

17. Lourdes Moreno, IWWOST, NY, USA, July 2008
AWA: Accessibility for Web Applications
Case study in specific method. Example 1
To comply with guideline 1.2 according to WCAG standard:
• Guideline 1.2 Time-based Media: Provide alternatives for time-based
media
• There are different success criteria of guideline 1.2
WCAG 2.0 Success Criteria S.C. Level WCAG 1.0
Checkpoints
Priority
1.2.1. Audio-only and Video-only (Prerecorded): A 1.1 A
1.2.2 Captions (Prerecorded) A 1.4 A
1.2.3 Audio Description or Full Text Alternative: A 1.4. A
1.2.4 Captions (Live) AA 1.4. A
1.3 A
1.2.5.
Audio Description
AA
1.4 A
1.2.6 Sign Language AAA Not mapping
1.3. A
1.2.7
Audio Description (Extended)
AAA
1.4. A
1.2.8 Full Text Alternative AAA 1.4. A
1.2.9 Live Audio-only AAA 1.1. A

18. Lourdes Moreno, IWWOST, NY, USA, July 2008
AWA: Accessibility for Web Applications
Case study in specific method. Example 1 (2)
In this case, to comply with guideline 1.2 , standard concepts such as
media, caption, audiodescription, etc. have been abstracted at the
metamodel level.
• An accessible multimedia element has
been modeled at the metamodel and an
instance of accessible meta object
element may be included in the models.
This contains the necessary knowledge to
comply with the guideline and success
criteria.
• The designer will be able to use
instances of multimedia elements. These
objects will have an alternate content
which will be required to comply with the
WCAG guideline.

19. Lourdes Moreno, IWWOST, NY, USA, July 2008
AWA: Accessibility for Web Applications
Case study in specific method. Example 2
To comply with guideline 1.3 according to WCAG standard:
• Guideline 1.3 Adaptable: Create content that can be presented in different ways
(a simpler layout, for example) without losing information or structure
• For success criteria 1.3.1 the technique H42 is recommended: Using h1-h6 to
identify headings. The applicability is to use HTML and XHTML heading markup
to convey the structure of the content. This can be used to:
– Distinguish the main content from navigation bars, graphic banners, etc.
– Show the organization of material within the main content.
– Use assistive technology to jump directly to the appropriate heading and begin
reading the content.
• Additional advantages: SEO (Search Engine Optimization), etc.
WCAG 2.0 Success Criteria S.C. Level WCAG 1.0
Checkpoints
Priority
1.3.1. Info and Relationships A 3.5, 3.6, 3.7 AA
5.1, 5.5 A
12.3, 12.4 AA

20. Lourdes Moreno, IWWOST, NY, USA, July 2008
AWA: Accessibility for Web Applications
Case study in specific method. Example 2 (2)
In this case, to comply with the success criteria 1.1.3 of guideline 1.1
(WCAG 2.0), it is necessary to have semantic information about the
organization of web contents. For this purpose, this knowledge should
be included in the models.
• After a detailed study of the OOWS method, this knowledge has been
detected in the navigation model.
• From this navigation model the main content and its associated
semantics can be inferred.
• In the next phase this inferred knowledge will be used in Model2Text
transformations and the generation of the final Web code.
For example:

21. Lourdes Moreno, IWWOST, NY, USA, July 2008
«view»
Member
«view»
WorkOn
«view»
Entity
The “Title” element will be the semantics
associated with <<context>> Members
The heading element level one,
“h1” will be the semantics
associated with Member “class”
The heading level two, three, ..,
h2..h6, will be the semantics
associated with Entity, group..
OOWS navigational model and
navigation context

22. Lourdes Moreno, IWWOST, NY, USA, July 2008
Success Criterion 2.4.2 [Page
Titled]
Criterion 1.3.1 [Info and
Relationships]

23. Lourdes Moreno, IWWOST, NY, USA, July 2008
• Web accessibility problems are increasing with the rapid advance of web
technologies and how these are being used.
• Trends in the development of websites have been observed , with ad-hoc
designs which in most of the cases do not follow any methods nor standards.
• This view complicates the establishment of procedures on how to include
accessibility criteria from the start of the development process.
• From an engineering perspective, the solution should be guided towards the
training of those professionals who develop websites. Methods which help and
guide the processes in order to achieve the objective of accessibility should be
used.
• From this perspective, the question is whether or not to integrate mechanisms
of accessibility following web engineering methods.
• An approach based on MDA is introduced as a first step.
• Future research: we are working on the AWA definition and validation on
specific methods such as OOWS.
Conclusions

24. Lourdes Moreno, IWWOST, NY, USA, July 2008
"A MDD approach for modelling web
accessibility“
Lourdes Moreno
This work has been supported by The Spanish
Center of Captioning and Audiodescription
(CESYA) and TIN2004-0783 Project (Software
Processes Platform: modelling, reuse and
measurement)