|Volantis' Multichannel Server product provides
support for the creation of web sites and applications that can be accessed from a wide
variety of different devices. It is based on a number of device-independence principles
which have proven themselves in the practical implementation of a significant number of
web sites and applications. These sites can be accessed from a wide variety of different
devices, including a large number of WAP and i-mode mobile phones, various digital
television systems, a wide range of Personal Digital Assistants, personal computers,
workstations and even systems that use voice as the only modality.
Key for authors is
the device independent markup language, based on familiar standards and incorporating
powerful functional abstractions. Additional abstractions are used for device dependent
information, such as stylistic specifications and data concerning the physical placement
of presentation elements. These abstractions are organised in ways that allow authoring
costs to be managed. Definitions can be reused and shared where appropriate, without
compromising the ability to provide highly customised presentations where desired.
The adaptation mechanism employs the abstractions together with delivery context, key
information about the device and the network in use. The delivery context includes
information taken from a comprehensive device repository in addition to information
transmitted by the device itself. The authoring tools associated with the products help
insulate authors from the need for expert knowledge of the devices in use, while providing
information that can be useful to them where necessary. This presentation will describe a
number of the fundamental principles on which this particular approach to device
independent site authoring is based.