An Ontology for Accessibility Requirements Specification

1
An Ontology for Accessibility Requirements
Specification

• Kristina Masuwa-Morgan

2
Aims of study

• Housed within the agenda of inclusive information
  technologies.
• Development of an ontology for accessibility
  requirements specification
• Codenamed AccessOnto
• Provides a database of reusable terms or
  semantics for specifying user traits and
  accessibility demands arising from these traits
  and from the access technologies applied by the
  users.
• Align requirements with guidelines initiatives
• Explore area of Accessibility
• Key drive from legislation
• WAI and other such bodies
• General concept of universal design
• Adaptivity
• Adaptability

3
Background

• Started as MSc project
• focus was network administration
• Realised challenges of supporting user diversity
• Then development of translation tool Shona to
  English
• Work in 1996 highlighted specific accessibility
  challenges
• Change of direction to development of Ontology
• Also change of supervisor at this stage
  influenced change in direction
• As tool evolved realised it is good tool for
  accessibility semantics in general

4
Study methods

• Primarily reading and prototyping
• Some limited contribution from primary data
• two questionnaire-based surveys
• requirements specification simulation to derive
  the terms of the ontology and demonstrate its
  usage
• The primary research also includes accessibility
  tests of a virtual learning environment (VLE)
  prototype developed to provide a requirements
  specification example aimed at demonstrating
  typical contents of an accessibility requirements
  specification and thus the concepts to be held in
  the accessibility requirements repository.
• The study is also supported by an accessibility
  research website (http//shapevle.cant.ac.uk)

5
Methods for developing actual Ontology

• Explored methods used by others
• Uschold and Kings methodology (Uschold and King,
  1995 Uschold, 1996 Uschold and Grüninger, 1996)
  - Enterprise Ontology and the Toronto Virtual
  Enterprise (TOVE) ontology.
• Grüninger and Foxs methodology (Grüninger and
  Fox, 1994 Uschold 1996 Uschold and Grüninger,
  1996)
• MethOntology (Gómez-Pérez, 1996 Fernández, 1996
  Gómez-Pérez, 1998 Fernández-López et al, 1999)
  developed within the Lab of Artificial
  Intelligence at the Polytechnic University of
  Madrid for a reference ontology.
• Bernaras et als (1996) method used for
  electrical networks ontology as part of Esprit
  KACKTUS project
• Sensus methodology proposed for the SENSUS
  ontology (Swartout et al, 1997) developed by ISI
  (Information Sciences Institute) Natural Language
  Group in the area of machine translation (Knight
  and Luk, 1994 Knight et al, 1995)
• Finally borrowed combination of techniques
• Main challenge was identifying structure of
  concepts and their relationships

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Leading Accessibility groups

• World wide web consortium (W3C,
  http//www.w3.org/)
• Web Accessibility Initiative (WAI,
  www.w3.org/WAI)
• WAI guidelines - http//www.w3.org/WAI/Resources/
  gl
• WebaBLE (http//www.webable.com/
• Trace Research and Development Center
  (http//www.trace.wisc.edu)
• Trace Center Accessible Software Guidelines
  http//www.trace.wisc.edu/world/computer_access/so
  ftware has a comprehensive guide to creating
  accessible software.
• UsableNET - http//www.usablenet.com
• Royal National Institute for the Blind
  http//rnib.com/
• CPB/WGBH National Center for Accessible Media
  (NCAM - http//ncam.wgbh.org/)
• Center for Applied Social Technology (CAST,
  http//www.cast.org/)
• Responsible for Bobby web evaluation tool
• Also develop CAST eReader (http//www.cast.org/str
  ategies/ud_reader.htm)
• Very little form HCI writers
• Almost nothing from SE
• Sommerville, idea of requirements database

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Leading accessibility initiatives

• HTML 4.0 provides accessibility features for
  overcoming problems with
• Images and Image maps
• Scripts
• Frames (vs. Layers vs. Shared borders)
• Table
• Interaction with Forms
• PDF and EPS documents
• Language identification
• Browser initiatives
• Text enhancement
• Table linearisation
• Speaking browsers
• Other browser initiatives
• Separation of content from text
• Style sheets
• Includes (can be performed by using webbots or
  Server side includes (SSI)
• Document identifiers
• Most basic form is the HTML ltTITLEgt tag
• Document type description (DTD)

Providing equivalent access ltIMG SRC
ALTalternative text ltNOFRAMESgt equivalent
content lt/NOFRAMESgt ltNOSCRIPTgt equivalent
contentlt/NOSCRIPTgt
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Shneiderman (2005)

• Characters, numerals, special characters and
  diacriticals
• Left-to-right versus right-to-left versus
  vertical input and reading
• Date and time formats
• Numeric and currency formats
• Weights and measurements
• Telephone number and address formats
• Name and title formats
• National identifiers Social-security, national
  identification, and passport numbers
• Capitalization and punctuation
• Sorting sequences
• Representation Meaning of icons, buttons,
  colours
• Pluralization, tenses, grammar, spelling
• Etiquette, policies, tone, formality and metaphors

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Industry leaders

• A lot of work in place
• Interaction styles
• Translation
• Encoding systems
• Accessibility features in operating systems
• Guidelines
• Evaluation tools
• Code prompting
• Case tools now include stereotyping
• Various projects adaptability and adaptivity
• Avanti
• GUIB
• Composite Capabilities/Preferences Profile
  (CC/PP)
• Hardware platform
• Software Platform
• Individual application http//www.w3.org/mobile/C
  CP

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Device Independence Principle (DIP)

• Derived from CC/PP
• Device independence
• Device independent web page identifiers
• Funtionality
• Incompatible access mechanisms
• Harmonisation of user experiences with given
  delivery contexts by description of dispositions
  of the given user
• Characterisation of delivery context
• Capture of adaptation preferences

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The ontology itself

• Currently mainly data repository
• Also housed within idea of widget-based
  development (reusability)
• DOM
• Active X
• Java Beans etc.
• Expected to promote migration from requirements
  to design
• Developed using XML(S) but to be rolled over to
  increase ontological expressivity
• perhaps DAML OIL or XOL
• Mainly relational model, at moment more as
  thesaurus
• But also supports tree structure plus embodies
  concept of case frames

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OMG model
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Select Stereotyping initiative(1)
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Select Stereotyping initiative (2)
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Select Component factory concept
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AccessOnto implementation
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Three repositories

• An interface object-action repository
• ltRelationshipsgt object
• General purpose objects ltObjectClassesgt
• ltUserAgentsgt object
• Document type ltDocTypesgt object
• ltCountriesgt
• ltLanguagesgt object
• ltAccessibleInterfaceObjectsgt TaskActions
  KeyCodes InterfaceObjects
• TaskActions constrained by TaskTypes
• Mainly evokes general idea of isolating
  primitives
• Largely borrowed from linguistic models
• Avoids conflict for reserved keys but also
  generally lends to reusability
• A guidelines repository
• A user profile repository

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Exemplary spec (1)
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Exemplary spec (2) Understanding from which
accessibility requirements are derived
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Conclusion/Achievement

• Useful tool for meting out legislation
• Reusability Mainly Accessible Interface objects
• Generalisable terms
• Minimisation of requirements spec
• Country and language traits
• Assistive Technologies and their capabilities
• Short cut key lists
• Interaction conflict resolution
• Potential for supporting migration from
  requirements to design
• VLE

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Future work

• Increase expressivity
• Relationships constrain each other/conflict
  management
• E.g
• ltTaskActionsgt must be constrained by ltTaskTypesgt
• ltObjectClassesgt plus all special objects must be
  constrained by Relationships
• Associations must be constrained by what is there
• Knowledge acquisition subsystem Inference
  engine
• Supporting CASE tool or UML DTD
• Currently only captures static concepts
• Hope to extend to include concepts relating to
  adaptivity
• Inclusion of code constructs