A Personalisable Electronic Book for Video-based Sign Language ...

predominant approach to the design of WWW-based hypermedia systems. A core of AH functionality is viewed
as a client technology of one or more user interface and database servers (UISs and DBSs, respectively). In the
case of KSO, the UISs are WWW-browsers, such as Galeon, Firebird and Internet Explorer, and the DBS used is
PostGreSQL (Momjian B, 2001). The personalisation functionality implemented in KSO is represented by the
shaded package.
Figure 2. A General, Open Architecture for WWW-Based Hypermedia
Broadly, once a request has been captured, from a user, for a hyperpage, it is channelled directly into the core of
AH functionality. If the request is simply for a hyperpage to be shown, the core responds by composing a
hyperpage specification and then rendering its digital content into a hypermedia presentation that can be
displayed by a UIS. This composition process includes the querying of the PostGreSQL DBS, in order to fetch
references to digital content. In KSO, hypermedia presentations consist of signing video clips, textual
descriptions and assessment exercises. Other requests allow users to tailor hyperpage specifications and thereby
personalise their hypermedia presentations. Such personalisation requests utilise meta-data, in the form of
annotations, which provide semantics for the content of hypermedia presentations.
Hypermedia Presentations within KSO
A hypermedia presentation is defined to be a collection of hyperpages, whose topology enables navigation
between them. Within KSO, hyperpages are dynamically generated from hyperpage specifications. A
hyperpage specification specifies a sequence of information units, known as chunks. Chunks contain digital
content, such as video clips, text and graphics. Each chunk is comprised of a specification of its content and a
specification of how to present (or render) this content. Content specifications may be comprised of the content
itself (as is the case with many of the textual descriptions in KSO) or a reference, in the form of an SQL query,
that, when executed, evaluates into content, as is the case with the signing digital video clips available in KSO.
Figure 3. The Structure of a Hyperpage
Rendering specifications define how the digital content, defined by a content specification, is to be presented by
a UIS. They take the form of a formal text in a language that the UIS can render (e.g., HTML). There is a
binding between the two specifications, which is achieved by interdispersing the renderable text with variables
that reference the digital content of the content specification.
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