evaluating the accessibility of rich internet applications

Evaluating the accessibility of Rich Internet Applications

Nádia Fernandes, Daniel Costa, Sérgio Neves, Carlos

Duarte, Luís Carriço

W4A 2012 – Accessible Web 2.0

Motivation

• The Internet has become an indispensable tool for our everyday life

• And it is used by all kind of people

– With different physical and/or mental capabilities

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• The content of Web pages must become accessible to all users

• Developers need a way to help them implement an accessible page

• Tools should be provided to enable evaluation of the accessibility

Problems

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• The Web Content Accessibility Guidelines (WCAG)– A set of best practices for developing an accessible

Web page

• Automated accessibility evaluators– QualWeb (Nádia et al)

– Achecker

– And more…

Solution

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• Web pages are no longer static content displayers

• With the Web development, Rich Internet Applications are becoming a trend

• New elements are introduced on the Dom tree triggered by javascript functions

New Challenges

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• QualWeb 3.0

– New WCAG techniques evaluated (including CSS techniques)

– Added a new module that triggers and observes changes made on the Dom tree

New approach

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Architecture

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• This component is responsible for activating interactive elements in the HTML document– For each interactive element it is attached a

function (Crawler) that triggers this element periodically

– At the same time there is an Observer which analyses the Dom tree to see if it has changed

– A change in the Dom tree is considered a new state of the RIA

Interaction Simulator

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• The evaluator receives the new state and performs the evaluation

• 20 HTML WCAG 2.0 and 6 CSS WCAG 2.0

• Then generates an EARL report

QualWeb evaluator

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• 5o inspiring Web applications

– http://speckyboy.com/2009/09/02/50-inspiring-web-application-and-service-web-site-designs/

Experimental study

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Goal

• The goal of this experiment is to validate this new approach

• Understand if it is possible to automatically trigger changes on the Web page

• Understand if those changes affect the accessibility of the page

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Results

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• There was an average of 5 different states per page– The number of fails and warnings increased 4% and

10% in comparison with the original state

• In this experiment the average of pass results is 28% , fail results represent an average of 12% and 60% for warnings.

• 43% of the Warning results come from the CSS evaluation

Results

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Advantages

• The main advantages are:

– The evaluation is made on browser environment

• VS “Offline” evaluation

– Evaluates WCAG 2.0 techniques (HTML and CSS)

• VS WCAG 1.0

– Can evaluate parts of the Web page that were otherwise unreachable

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• The results obtained show that it is possible to evaluate automatically states that can be triggered without human intervention

• We demonstrated that there are differences when evaluating different states of the Web page

• We have developed a more complete evaluation of Web pages

Conclusions

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• Implement more WCAG 2.0 techniques

• Perform more tests

• Remove some limitations we had

Future Work

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• Daniel Costa – dancosta@di.fc.ul.pt

• Nádia Fernandes – nadiaf@di.fc.ul.pt

Questions?

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