A MDD approach for modelling web accessibility
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Lourdes Moreno, Paloma Martínez and Belén Ruiz Computer Science Department, Universidad Carlos III de Madrid, Spain Title: A MDD approach for modelling web accessibility Conference: 7th International Workshop on Web-Oriented Software Technologies (IWWOST 2008) [Web], in conjuntion the 8th International Conference on Web Engineering (ICWE'2008) [Web]. July 14, Yorktown Heights, New York, 2008. Idioma: inglés
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A MDD approach for modelling web accessibility
- 21. Lourdes Moreno, IWWOST, NY, USA, July 2008 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 «view» Member «view» WorkOn «view» Entity
- 22. Lourdes Moreno, IWWOST, NY, USA, July 2008 Success Criterion 2.4.2 [Page Titled] Criterion 1.3.1 [Info and Relationships]
- 24. Lourdes Moreno, IWWOST, NY, USA, July 2008 "A MDD approach for modelling web accessibility“ Lourdes Moreno [email_address] 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)
Notes de l'éditeur
- Good afternoon I'm Lourdes Moreno. I will present the work: “ A MDD approach for modelling web accessibility ”. It has been made in conjunction with Paloma Martinez y Belen Ruiz, from the University Carlos III of Madrid, Spain As motivation Before to pass to presentation, I am going to show some usual accessibility problems on the web
- 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 an 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.
- 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. Some of these are: - In some countries, legislation about web accessibility. - Standardization: W3C, 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 are they 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.
- The purpose of AWA is to offer flexibility in its use so that it can be adopted by different approaches but to comply with the minimum conditions required. These would be: 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 team 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
- Other baselines would be: 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: One needs to: To elicit the requirements in order to identify other accessibility requirements. Also one needs to include aspects of modelling accessibility. And to include plans and management of accessibility such as accessibility monitoring When new technologies become available, accessibility solutions need to be found: Some examples of these new technologies would be The Web 2.0, n ew devices and Web interfaces to improve the user's experience such as Rich Internet Application. … .
- 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. Some of these would be: Following the WCAG standard in the whole process. Considering Usability , following user-centered design. Including mechanisms to safeguard accessibility throughout the life cycle of web applications. Including management of accessibility during the process And including system management software of complaints from users. Components affected by accessibility, directly or indirectly, during the development process are detected in the entire life cycle of the application. The aim is to detect and avoid resulting accessibility problems and define and prepare Accessibility mechanisms .
- If the different kinds of requirements are considered, there are several accessibility mechanisms. In MDA development process, there are different c omponents affected. The accessibility mechanisms have to be included in the different application points in the process: Application points such as Domain specific metamodel, model extensions, model transformations and final Web code generation. the Figure show: the concept image have been defined at the metamodel MOF that includes required attributes to comply the standard WCAG such as the &quot;AlternativeText&quot; &quot;AlternativeLongText&quot; (1.1. of WCAG 1.0 and 1.1.1 of WCAG 2.0), and may be included in the PIM models, which contain the knowledge included necessary for the web code generation in the final phase.
- To integrate accessibility mechanisms into the Model development process, web engineering methodologies have been followed. This approach has been followed in this work, with the use of the abstraction mechanisms of the model-driven development (MDD) including its accessibility requirements. Although the MDD has been followed, the process must be iterative, guided by continuous evaluation and tested by users. In this project, modelling techniques of Web engineering methods are used, based on the MDA development process. The objective is to be able to use any method rather than a specific one, and to be able to include accessibility aspects in the models of the method concerned
- In this work, a first approach to the domain-specific metamodel for Web accessibility has been offered. At the metamodel level, the accessibility mechanism has been included: => Concepts and their relationelationships of standard accessibility in the WCAG 1.0 current version and the WCAG 2.0 next version have been modeled.
- 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 for these accessibility aspects to be encapsulated in the whole development cycle. EMF (Eclipse Modelling Framework) with Ecore language has been used. Investigation 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 standard accessibility. - Some concepts modeled at the metamodel level will pass to the model level.
- 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. Currently there is an ongoing case study looking into the OOWS Method following a MDA process. I am now going to show you some of the study’s preliminary findings that are linked to accessibility requirements such as the compliance with some guidelines according to WCAG standard.
- The Guideline 1.2 said that : Time-based Media: Provide alternatives for time-based media And there are different success criteria of guideline 1.2 such as to provide an alternative as caption, audiodescription, etc with different accessibility levels
- In this case, to comply with guideline 1.2 , standard concepts such as media, caption, audiodescription, etc. have been abstracted at the metamodelo level. An accessible multimedia element has been modeled in 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 guideline WCAG.
- Guideline 1.3 said that “Adaptable is to Create content that can be presented in different ways (a simpler layout, for example) without losing information or structure” The guideline has a 1.3.1 success criteria, and this one has H42 technique that is recommended, the technique indicates that “ 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.
- 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:
- The OOWS navigational model and navigation context is showed and the result web page. In this navigation context, the “Title” element will be the semantic associated with <<context>> Members. The same way, the heading element level one, “h1”, the main content, will be the semantic associated with Member view class And The heading level two, three, .., element will be the semantic associated with Entity, Rgroup view class.
- And these inferred semantic will be include in the the generation of the final Web code. In the Title, them, to comply success criterion 2.4.2 And In the headings with the Compliance with success criterion 1.3.1
- To conclude, 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 will work on the AWA definition and validation on specific methods such as OOWS.