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).
Constantine Stephanidis - ICS-FORTH
Tel: +30 81 391741