The AVANTI Web Browser
by Constantine Stephanidis
The increasing use of Internet and the World Wide Web
as a primary medium for communicating information is creating numerous
opportunities and challenges for the population at large. The importance
of providing mechanisms for delivering information to 'all' potential users
in the context of the emerging Information Society has, therefore, increased
significantly. The EC ACTS AVANTI AC042 project aims to address the interaction
requirements of disabled individuals using Web-based multimedia applications
and services. This article presents the AVANTI Web browser, which employs
user interface adaptability and adaptivity techniques, in order to provide
accessibility and high-quality interaction to able bodied, blind and motor-impaired
users.
The main modules of the AVANTI system are:
- a collection of multimedia databases which are accessed through a common
protocol (HTTP) and provide mobility information for disabled people
- the AVANTI server which: maintains knowledge regarding the users; retains
a content model of the information system; and adapts the information to
be provided, according to user characteristics
- the AVANTI Web browser (acting as the front-end to the AVANTI system),
which aims to satisfy diverse end-user abilities, requirements and preferences,
as well as different usage contexts.
The design and development of the AVANTI browser's user interface have
followed the Unified User Interface Design Methodology (U2ID), developed
in the context of the EC TIDE ACCESS TP1001 project. The resulting unified
interface is a single artefact, in which adaptability and adaptivity techniques
are employed, in order to meet the requirements of three user categories:
able bodied, blind and motor impaired.
In the present context, adaptability refers to the process of selecting/modifying
(aspects of) the user interface during initiation of each interaction session,
according to user characteristics (eg user abilities, particular user expertise)
and usage characteristics (eg kiosk vs. desktop use) that are known prior
to interaction and are assumed to remain unchanged within a single session.
Adaptivity, on the other hand, refers to the process of selecting / modifying
(aspects of) the user interface dynamically, according to interaction situations
that are detected at run-time (eg user has a high error rate, user is unable
to carry out certain tasks).
Adaptations are supported through the co-operation of the browser and
the user model server (a component of the AVANTI server); the former monitors
user interaction and notifies accordingly the latter, which, in turn, draws
inferences on the state of the interaction (ie detects interaction situations),
successively updating its knowledge. The updated knowledge is used by the
user interface to decide upon and self-adapt.
Adaptations are applied at two different levels of the interface, namely
the syntactic and lexical levels. Syntactic adaptations refer to the selection
of different interaction styles, for the instantiation of interface tasks.
More specifically, for each task a user may perform within the AVANTI user
interface, different design and implementation interface instances (styles)
have been developed, to cater for different user characteristics, following
the Unified User Interface Design Methodology. Lexical adaptations refer
to the selection of those attributes of physical interface objects that
are appropriate for a given user (eg font size, colours, speech parameters).
The adaptation logic in the AVANTI browser is realised as a set of syntactic
and lexical adaptability and adaptivity rules. The rules are not hard-coded
into the browser, but are rather maintained in a separate module, so that
they can be modified independently. Thus, the adaptation logic of the browser's
interface can be re-defined (by changing / enhancing the rules), without
requiring modifications in the browser itself.
Additional interface features that have been included in the AVANTI
browser, in order to meet the requirements of the target user categories,
include support of multiple interaction metaphors, special I/O devices
and extended navigation functionality.
Alternative metaphors have been developed for the different usage contexts
of the AVANTI system. A desktop application and an information kiosk metaphor
have been designed, to be used for stand-alone access to the Web, and as
a front-end to databases at information kiosks, respectively.
Furthermore, special purpose input/ output devices have been integrated
into the system to support blind and motor-impaired individuals: binary
switches, joysticks, touch screens and touch tablets, speech input and
output, and Braille output.
Additionally, the AVANTI user interface implements features new to Web
browsing applications, that assist and enhance user interaction with, and
navigation within, the system.Some of these features have been used in
hypermedia navigation systems and have proven to be of great assistance
to users, while others have been developed specifically for the AVANTI
system. Such features include: enhanced history control for blind users,
as well as linear and non-linear (graph) history visualisation for sighted
users; resident pages that enable users to review different pieces of information
in parallel; link review and selection acceleration facilities; document
review and navigation acceleration facilities; enhanced mechanisms for
document annotation and classification; and, enhanced intra-document searching
facilities.
Figure: A snapshot of the AVANTI Web Browser
The figure shows a snapshot of the prototype version of the browser
while a motor-impaired user is interacting with it, where the following
features can be observed: link-bar (a separate pane in which all the links
of the document are replicated for quick review and selection); adaptive
guidance (in response to the detection of the User is disoriented situation
by the user model server, the interface has activated a guidance dialogue
to assist the user in using the document history facility); scanning for
motor-impaired users (scanning toolbar at the top of the window; scanning
focus on the OK button of the guidance dialogue).
The AVANTI browser is currently under evaluation through user trials
that have been planned to test the effectiveness and usability of the overall
system, both in laboratory and real life usage. Future work involves the
development of guidelines for unified user interface design of Web browsers,
as well as standardisation activities regarding Web accessibility by all
users.
The AVANTI Consortium
Part of the work reported in this article has been carried out in the
context of the ACTS - AVANTI (AC 042) project of the European Commission
(DG XIII). The AVANTI consortium comprises: ALCATEL Siette (Italy) - Prime
contractor; CNR-IROE (Italy); ICS-FORTH (Greece); GMD (Germany); University
of Sienna (Italy); MA Systems (UK); MATHEMA (Italy); VTT (Finland); ECG
(Italy); University of Linz (Austria); TELECOM ITALIA (Italy); EUROGICIEL
(France).
Please contact:
Constantine Stephanidis - ICS-FORTH
Tel: +30 81 391741
E-mail: cs@ics.forth.gr
