Abstract
The objective of
hypermedia design models is to produce a well-organised web site. The
organisation is undertaken at the level of a particular building-block – an
abstract data unit which may match a frame, paragraph or region on a Web page.
The increasing sophistication of these models allows the designer to deal with
interaction and personalisation, but precludes one of the basic features of
hypertext – the text itself. This paper argues that this oversight remains a
fundamental problem because the component of content production for many web
sites is not an abstract data unit but the concepts embedded in the paragraphs,
sentences and words
of the content regions. Consequently there is a gap between the organisation of
material and the origination of material that is not well-addressed by current
design methods. The paper considers the problem of concept modelling in the Semantic
Web, its implementation in various hypertext environments and whether this
approach can inform the current generation of hypermedia design models.
General Terms
Documentation,
Design.
Keywords
Web Design
Methods, Hypermedia Design, Open Hypermedia, Semantic Web.
1
Introduction
Hypermedia design
models have been principally aimed at public, data-rich web sites
These kinds of
sites provide different kinds of information for the user in the form of more
complex content (e.g. articles, mail
messages) rather than easily-processed data. However, even the ‘data-oriented’
Web sites show the challenge of content – consider the web page shown in figure
1 taken from (an original version of) the WebML tutorial[1].
It shows how the design method helps to identify the type of the information displayed to the user, but it stops short
of modelling the significant concepts and knowledge fragments, which compose
the information itself (e.g. the
named entities, events and activities). Consequently the designer can only take
advantage of the fact that this page contains a “news article”, and cannot
assist the visitor to the page who is interested in the fact that it is about David Bowie and may want to follow
up some of the facts that are mentioned. (What is the connection with Lou Reed?
What was New Romanticism?)
As well as considering their (deep web) public
information provision, organisations have also amassed large intranets
(private, multimedia Web sites) in an attempt to capture their corporate
knowledge [23] and are increasingly concerned with effective information access
as a part of the imperative of knowledge management [39]. These collections
have typically been gradually amassed in an unsystematic fashion, potentially
from many parts of an organisation over a long period of time (relative to the
structure of the organisation itself). Consequently, they will not been the
subject of a single, disciplined design process, and may exhibit unconstrained
and inconsistent metadata, vocabularies and indexing terms. The technologies
which support these intranets are document
management systems – databases of un-structured or semi-structured
documents rather than semantically well-structured material.
Figure 1: WebML Page Decomposition
Rather than a Web
site that forms a well-defined interface at the boundary of the organisation
(to a customer or trading partner), the information contained in a document
management system is related to the internal working of the organisation. The use to which the information is put after
publication varies with the role of each user within the organisation and the
type and context of the information that has been assembled. As the intranet
grows in size and complexity, it becomes impractical to build and use it in the
present ad hoc and labour intensive fashion.
Consider the
following example: a manager writing a policy statement is required to draw
together information held in a number of business documents: corporate vision
statements, corporate strategy documents, departmental policy documents,
management summaries, financial reports, public relations statements etc. While reading the content of those
documents, the manager will also want to know their purpose (e.g. the intended audience) and
authorship (e.g. the authors’ role
and position of influence) in order to be confident about any inferences made
from the documents.
Hypermedia design
methods help to identify the kinds of information needed to provide appropriate
navigational access; document management systems help to collect metadata and
provide classification and querying support to locate relevant information.
However, managers do not often have sufficient time for unbounded browsing and
searching to evaluate the appropriateness of supplementary documentation. What
they could reasonably ask of a semantically-enriched support environment is to
identify relevant material from appropriate documents, based on the
context in which new material is being written.
The above scenario
is not well supported by ad-hoc searching, but neither is it easily implemented
with current web and hypermedia design models. Such models address the
relations between information assets to provide site design and navigation
features at the level of the document, unit or Web page, but fail to identify
the connections between related information fragments for example an
institution’s three critical success factors and three section headings in the
middle of its corporate strategy document..
Not only should
such ‘legacy’ knowledge be accessible to the user of such a system, but new
documents should be published in a form that facilitates reuse of the new
knowledge embodied within them, providing explicit (hypertext) references to
the sources of any reused knowledge.
The Semantic Web
[5] augments the Web with explicit statements of document semantics, allowing
the Web to be used as more than a human-browsable repository
of information. The meaning of the published documents, knowledge about their
authors and the reasons for their publication are all used to infer
contextually appropriate associations, i.e.
knowledge. This paper discusses the possibility of using Semantic Web
techniques to improve hypermedia design models to support the kind of scenario
developed above.
The paper
continues by discussing current hypermedia and web design models (section 2)
and their limitations (section 3). In this context, it introduces the Semantic
Web (section 4) and some hypertext systems which incorporate some of its
techniques and technologies (section 5). Finally we consider whether these
techniques can be successfully applied to solve the shortcomings of Web
development methods.
2
Engineering Web Design
In this section we
briefly present several well-known hypermedia or web-based design models and
methods, focusing on their similarities and highlighting the gap that is to be
addressed by our approach. Most of the currently available design methods (i.e.
those described here) are model-driven and focus on the design stage of the
hypermedia applications development life cycle or framework as proposed by Lowe
& Hall [31]. All
emphasize the need for an
incremental and interactive development process [27], and generally consist of
several orthogonal modelling dimensions. The typical modelling layers used in
the process of designing an application include the conceptual or structural
level (information
domain structure and design), the hypertext level (composition and navigation structure
of the application), the presentational level (user interface or application
look-and-feel design), personalization level (customization design), and the
implementation level. The extent of coverage
of these layers varies from one design model to another, and most of them
formally focus on three layers, that is the conceptual, hypertext and
presentational levels. At the conceptual level, the information domain is
captured and modeled using three main design techniques:
- Entity-Relationship: information
objects and data
structure described by means of entities and relationships,
- Object-Oriented: information
objects modeled as objects/classes.
- Ontology-based: information
objects modeled as ontology classes.
The concept
of views or perspectives is used at the hypertext level to enable the modeling
of different applications, providing static views over the same conceptual model. A few methods such as
WSDM, OOHDM and WebML provide support for more flexible personalization
features (content, link, structure or context customizations) [14, 37, 9]. The
compositional and navigational structure of an application is built on nodes
(pages, navigation units, content units, slices or cards) and different types
of links (perspective, structural, application link, etc) between them. The
navigation units (nodes units) are mapped to conceptual units (entities or
classes) to display the information or data at rendering/presentation time.
Although the
design methods and models share at a higher level the similarities (common
approach) described above in modelling web applications, they have several
differences, including their main application domains, the level of coverage of
the design process, the level of support provided at different stages.
HDM (Hypermedia
Design Model) is an early E/R-based design model proposed by Garzotto et
al. [18] to define the structure and interactions in large scale and
read-only hypermedia systems. The model is suitable for domains with a high
level of organisation, modularity and consistency. It focuses on hierarchically
describing the information objects in terms of entities made of components
containing units of information as well as the navigation structure,
independently of their implementation. This navigation structure comprises perspective
links between units, structural links between components, application links
between entities, components or units, index and guided tours. The presentation
design consists of slots (unit of information) and frames (grouping of slots).
RMM (Relationship Management Methodology) [26]
is E/R-based, suitable for structured
hypermedia applications and its design process
consists of seven steps: entity-relationship design; slice design (grouping entitie’s attributes as node/presentation units called slice
or M-slice); navigational design (access methods: link, menus, index, guided
tour, indexed guided tour); protocol conversion design (converting design
components into physical objects); user interface design (screen layouts);
run-time behaviour design and construction and testing.
OOHDM
(Object Oriented Hypermedia Design Model) is an OO-based design model that
allows the specification of hypermedia applications as navigational views over
the conceptual model [37]. Its design process consists of four main dimensions
(See Table 1) and has recently been extended to formally cover requirements
gathering [21] and personalisation modelling [36]. Navigation units or nodes are mapped to
conceptual classes, and the design and generation of OOHDM-based read-only web
sites is supported by a CASE tool called OOHDM-Web [38]
The
Enhanced Object-Relationship Model (EORM) [28] is an OO-based methodology whose
major characteristic is the representation of relationships between objects
(links) as separate objects. Links are therefore first class objects stored in
reusable libraries, facilitating the mapping of relations into link class. The
method is based on three frameworks: Class framework, Composition framework,
GUI framework. EORM has early prototyping of user interfaces,
a richer typology of links and a CASE tool (ONTOS Studio) to support the
modelling process.
SOHDM
(Scenario-based Object-oriented Hypermedia Design Methodology) is another
OO-based approach focusing on process-oriented hypermedia systems to support organisational
processes [30]. Scenarios are defined during the domain analysis and serve as the
basis for object modelling and navigational design. Different types of OO views
can be generated from the domain object model to compose a new application. It
consists of six phases (See Table 1)
The
Web Site Design Method (WDSM) [14] is a user-centred approach, as the
application model is based on the user model, identifying user classes and
their preferences and views. The design process for a reead-only
web site comprises three main stages (See Table 1). The conceptual design consists
of both the object modelling (which can be E/R or OO based) and navigational
design.
OntoWebber is an ontology-based approach to building read-only
web sites, focusing on integrating heterogeneous data sources to build
data-intensive web portals [43, 44]. A Domain Ontology serves as a reference ontology for data integration and content
modelling, and as the starting point for the entire web site design. The site
view modelling or site view graph consists of the navigation, content and
presentation models; and further steps include personalisation and maintenance
models (See Table 1). Nodes or navigation units are called cards which are
mapped to ontology classes via the content model and the overall design is
represented by an XML-based meta-schema using RDF and DAML+OIL [43]
WebML (Web
Modelling Language) is a recent high level, model-driven, and E/R-based (compatible
with UML class diagrams) design approach allowing a conceptual specification
and automatic implementation of data-intensive web sites [9]. Four main
orthogonal dimensions cover a web site specification (See Table 1) and
navigation units (content units) in the hypertext model are mapped to relevant
entities in the structural schema. A web site description is represented as a
platform-independent XML meta-schema, and every concept derived from the
specification has an associated graphical notation and XML representation.
WebML extensions [6] allow interactive content management with entry units to
update the site content, and the model has a CASE tool called WebRatio.
Overall,
most current web design models provide users with model-driven approaches for
the systematic design of high-level, read-only, well-organized, and easy to
maintain web applications in different domains. Their coverage of the
application life cycle focuses on the design stage with different levels of support provided at
different orthogonal dimensions in the design process. Some are sustained by CASE tools for automatic
implementation and generation of web sites. However, several limitations
persist with regard to content modeling and management and the resulting
linking capabilities.
|
Design
process |
Navigation
structure: Nodes and navigation units (nu) |
Interactivity |
Modelling
Technique |
|
|
HDM |
1.
Authoring-in-the-large 2.
Authoring-in-the-small |
Entities,
components, units (nu) |
Read-Only |
E-R |
|
RMM |
1.
E-R design 2.
Slice design 3.
Navigational design (slice diagrams) 4.
Conversion protocol design 5.
IU screen design 6.
Runtime behaviour design 7.
Construction and testing |
outlines,
slices (nu) |
Read-Only |
E-R |
|
WebML |
1. Structural model (data design) 2. Hypertext model Composition model Navigation model 4. Presentation model 5. Personalisation model |
Pages,
Content
units (nu) |
Read-Write |
E-R
/ OO |
|
OOHDM |
1.
Conceptual design 2.
Navigational design navigational
class schema navigational
context schema 3.
Abstract interface design 4.
Implementation |
Navigation classes (nu) |
Read-Only |
OO |
|
EORM |
1.
Class framework 2.
Composition framework 3.
GUI framework |
Navigation classes (nu) |
Read-Only |
OO |
|
SOHDM |
1.
Domain analysis 2.
OO modelling 3.
View design 4.
navigational design 5.
Implementation design 6.
Construction |
classes |
Read-Only |
OO |
|
WSDM |
1.
User modelling 2.
Conceptual design Object
modelling Navigational
design 3.Implementation
design (presentation) 4.
Implementation |
Navigation classes (nu) |
Read-Only |
E-R
/ OO |
|
Onto-Webber |
1.
Domain ontology 2.
Site View modelling, navigation model content
model presentation model 3.
personalisation model 4.
maintenance model |
Pages,
Cards (nu) |
Read-Only |
Ontology |
Table 1 Web
Design Model features
3
Shortcomings of Web Design
Apart from WebML,
which provides extensions enabling content management features, most of the
methodologies have a static (data) view over the web site content and allow the
modelling of read-only web sites. The resulting applications are largely built
to present/publish the data, but not to manage the content. Consequently, many
of the methodologies and models described in the previous section take a simple
layered approach, separating the design issues so as to allow independence for:
·
Mapping the domain, in terms of its structure, content, work flow, etc.
·
Analysing the associations and relation in that domain
·
Presenting the information to appropriate users
A common weakness
with these approaches is the lack of ‘cement’ connecting the layers and the
missing means of mapping between the different layers [32], i.e. in practice the result of one
activity does not feed into the next.
At the hypertext
level, navigation units (cards, slices, content units, navigation classes,
slots, etc.) are generally mapped to
information units (entities, units, classes, etc.) in order to present the content in web pages, but the level
of granularity of these units does not allow authored links to reach the real
text inside units. Automated links are restricted to navigation units or groups
of navigation of units, and any link to/from the inside
of the units have to be manually added.
By contrast, Open
Hypermedia Systems (OHS) promote links to first class objects that are stored
and managed separately from multimedia data. The advantage of these systems is
that they allow links to be added to the multimedia content in a way that is
appropriate to the user and to the document contexts. Early OHS like Microcosm [12]
and Intermedia [41] have influenced the XLink Web standard [14] which allow
links to be added to Web documents independently
of their storage.
Navigation can be
viewed as a combination of hypermedia linking, information retrieval and
document management [40]. While navigation design is covered by all the major
models, none directly address the issue of hyperlinks in the content; some
(those based on HDM) even stipulate that links should not be placed in the content. This position arises concerning
links embedded at design time, clearly these embedded
links can become invalid when the context in which the webpage is used changes
[19]. Many other models restrict user navigation between pages/containers by the
use of buttons or links contained in toolbars or sidebars. These can are more
flexible, and can be changed at run time. However, usability studies show that “when they arrive
on a page, users ignore navigation bars and other global design elements:
instead they look only at the content area of the page” [34]. In other words, links should not be
completely ruled out of the content that the user is viewing.
Allowing links to
become first class objects that are only embedded in documents at the time of
viewing allows only those options appropriate to the users to be displayed. In
practice, this may be simply achieved by swapping different linkbases in and
out of use, thereby creating different paths through the same documents. In
addition, the choice of linkbases can be deferred to an agent thereby making it
adaptive to the user [2] and dependent on the context in which the user is
browsing the information space [15].
These open
hypermedia techniques allow the addition of links to material to good effect. These
links can either be extracted from databases or computed dynamically; it is
this freedom that should be subject to the discipline of the design process, to
allow the rationale and the mechanisms for choice to be clearly expressed and
tested for effectiveness. To enable the design process to inform a more
complete linking activity, a structured approach is needed that would enable
the microstructure (low level) of information objects (or documents’ content)
to be addressed and modelled.
4
Semantic Web
Hypertext is just
one example of the use of a family of techniques that are intended to transcend
the limitations of static, sequential presentations of text
In
The World-Wide-Web Consortium
(W3C) describes an ontology as
defining the terms used to describe and represent an area of knowledge (usually
called a domain), for use by people, databases, and applications to
share information [24]. An ontology merely specifies one
way of understanding the world, and different ontologies will be useful for
different things. Hence there could be two or more ontologies that describe the
same phenomena but are very different to each other – yet both could be, for
their own purposes, correct. An immediate Web application of ontologies is in searching – otherwise a
purely syntactic activity matching patterns of letters. Ontology-augmented
searches can determine that a page about “yetis” is relevant to a search for “monsters”,
because a yeti is a specific subtype of monster, even where the sequence of
letters m-o-n-s-t-e-r does not
appear.
To
link the computer-accessible semantics contained in an
ontology with the human-oriented semantics contained in the ‘content unit’
of a web page, a process of annotation is required. Formal statements in a standard Web language
(currently RDF [29]) refer directly to concepts in the ontologies and to some
content on the Web, enabling a program to determine that a particular string (a-b-o-m-i-n-a-b-l-e-
-s-n-o-w-m-a-n) in a particular document refers to a Yeti.
An
ontology is a formal
model that allow reasoning about concepts and objects that appear in the real
world and (crucially) about the complex relationships between them [17]. It
seems reasonable to imagine that some kinds of complex structures may be
required for discussing and exploring inter-relationships between objects when
we make hypertext statements about those interrelationships. Normal hypertext
design practice (above) is to analyse the texts themselves in order to devise a
suitable hypertext infrastructure. By contrast, ontologically-motivated
hypertexts derive the structuring of their components from the relationships
between objects in the real world.
5
Qualifying Systems
Many Semantic Web
developments have focused on the issues related to knowledge modelling and
knowledge publishing (ontologies, knowledge-bases, inferencing)
and as a result, tend to sideline the role of complex, user-centred documents.
However, ontologies have influenced a number of hypertext developments in
recent years, some of which bridge the gap between the (human-readable) Web and
the (machine-processable) Semantic Web.
5.1
COHSE
The COHSE project
(Conceptual OHS Environment, [8]) produced an experimental ontological
hypermedia system by combining an existing open hypermedia link service with an
ontological reasoning service to enable documents to be linked via the concepts
referred to in their contents. COHSE was particularly concerned with the authoring
process, tackling the problem that the manual construction of hypertexts for
non-trivial Web applications (where documents need to be linked in many
dimensions based on their content) is often inconsistent and error-prone [16].
Attempts to improve the linking through simple lexical matching had serious
limitations due to the uncontrolled method of adding links: many keywords turn
up in many contexts and there is no simple lexical basis for discriminating
important terms and significant links. The aim of the COHSE project therefore
was to combine the OHS architecture with an ontological model to provide
linking on the concepts that appear
in Web pages, as opposed to linking on simple
uninterrupted text fragments.
Ontologies are
used to describe the interrelationships between concepts embedded in the
documents to provide a new ‘catalogue of internal knowledge’ [3]. An
ontological hypertext environment needs to have some mechanism for interpreting
the ontology and exposing these concepts and relationships in the real world as
links (or other artefacts) in the hypertext. COHSE used a standard Web browser
controlled by an adapted link service which in turn used three
independent services to manipulate the exposed Document Object Model (DOM) of
the Web page, resulting in the effect of ontologically-controlled hypertext.
In Figure 2, the ontology service manages ontologies
(sets of concepts related according to some schema) and answers specific
queries about them. The ontologies are internally represented using DAML+OIL
[4] and queries are satisfied using the FACT reasoner
[25]. The purpose of the service is to answer fundamental questions about the
concepts in an ontology, for example: what is the parent of this concept, or how is this concept represented in a natural
language, or what concept does this
string describe or are these two
concepts similar or the same? Unlike other Semantic Web systems, COHSE’s ontology
server does not use specific relationships to answer ontology-specific (and
hence domain-specific) questions (e.g. who wrote this paper, or what
kind of person manages an academic project or who can be a chartered engineer?). The metadata service annotates regions of a document with a concept,
rather than the familiar case of annotating a document with a simple piece of
text. An XPointer is used to identify each region in
the document; a fragment of RDF that corresponds to a DAML+OIL statement
identifies the concept. The resource
service is a simple librarian that is used to lookup Web pages which are examples of a particular concept (i.e.
that can be used to illustrate a concept).
Figure 2 COHSE Architecture
for Ontological Hypertext
When a web page is
loaded, the ontology service provides a complete listing of all the language
terms that are used to represent the concepts in the relevant ontology. Each
language term is searched for in the document, and, if found, its associated
concept is looked up. The metadata service is also used to determine whether
any regions in the document have been manually annotated (allowing concepts to
be recognised even if the document does not use the ‘approved’ language terms).
Having identified the significant concepts in the document, the resource
service provides a list of documents that are about instances of this concept.
At this point, a
number of potential link anchors and destinations have been identified for the
page and decisions can be taken about whether the document contains too many or
too few links. In those circumstances, alternative links may be chosen from the
broader or narrower concepts in the ontology in order to expand or cull the set
of link anchors. The decisions about link culling and presentation are
controlled by behaviour modules which define the navigation and interaction
semantics of the resulting ontological hypertext.
5.2
CREAM
CREAM (CREAting Metadata [22]), is an ontology-based framework for
metadata and document creation. It is based on the Ont-O-Mat
tool, a component-based annotation and authoring system built around a document
editor and ontology browser. CREAM supports Semantic Web knowledge creation by
annotation both during and after authoring.
Annotation can be achieved by filling out knowledge templates under the
control of the ontology browser (either by typing values or by dragging and
dropping literal strings from the document editor). More interestingly,
documents (or content fragments) can be built by a process of
reverse-annotation; entries from the ontology or knowledge-base are used to
create text (e.g. Leslie Carr
is a researcher who works at
The major concern
of the CREAM framework is to create knowledge that can be used in Semantic Web
applications (e.g. querying,
inference and structured portal generation). It therefore uses ontologies
mainly for annotation purposes and achieves limited support for content
authoring as a by-product of the annotation activities. However, this support
is significant because in embryonic form it imposes a principled knowledge
framework on otherwise free-form textual material as it is being created.
5.3
ONTOPORTAL
Ontoportal is a
generic application framework for building ontology-based web portals [44]. It
shows how a semantic meta-layer of ontology concepts and relationships can be
instantiated or projected over existing weakly interlinked web resources to
generate a web portal meaningfully describing and linking the resources and
their relations. The framework provides facilities such as: exploration
(browsing an ontoportal); knowledge capturing
(content creation or update); thread discussion (on themes around the resources
being browsed); and searching (keywords search over the stored metadata); corresponding
to four main modes of interaction with users.
Producing a new ontoportal (an Ontoportal-based web portal) involves
creating and populating the domain ontology that can later be reused to
generate other ontoportals in similar domains, and
setting XML-based presentation rules for different display modes. Examples of applications
built from this framework include Metaportal (web
portal for the metadata research community) that can be found on the project
web site at http://www.ontoportal.org.uk/;
and two educational domain portals TPortal and XPortal[2]
Ontoportal is an
ontological hypertext system, therefore ontologies are
used to improve the navigational facilities of resulting web portal
applications. New types of links, that is conceptual links, are inferred from
the underlying domain ontology structure to enrich the linking between
resources and to enable complex queries to be answered by simply following
ontological links (query by linking).
In the systems
described in section 5, combinations of ontologies, knowledge-bases, document
services and hypermedia services have been produced to create some sort of conceptual
hypermedia system that supports the creation and linking of WWW documents at
retrieval time (as readers browse the documents) or at authoring time (as
authors create the documents).
None of these
systems fully addresses the concerns of hypermedia authoring in the context of
a web site; COHSE promotes the creation of links and CREAM promotes the
creation of (metadata or) text.
6
Requirements of Improved Web Methods
Existing web
design models suffer from a lack of ‘cement’ (as described in section 3), in
other words, they have no clearly defined way of moving from one stage to the
next. While each of the models and methodologies described in section 2 have
their own advantages and disadvantages [11],
they all emphasise the imposition of organising principles on a collection of
documents (by clustering, partitioning and decomposition). To inform the design
of other types of information environments, we require a model that will also
help expose the relationships within the content of the individual documents, e.g.
that bullet point 1 of a Company policy document is expanded in paragraph two
of the Departmental policy document.
We suggest that
these parallel requirements could be satisfied by an interleaved model (Figure
2). Ontologies have a dual role in expressing both large-scale
concepts/relationships and also discrete entities/specific instances,
consequently they may be used as the ‘cement’ that maps between the domain
analysis and hypertext navigation layers. Different ontologies would be used
for each of the user groups or the tasks to be undertaken by the web site, so
providing alternative perspectives and navigational paths through the
information domain.
Figure 3: Interleaved Models
The existing
models (white areas) examine the macro-structure of the collection (web site,
intranet, repository etc.) which is
used to design navigation and presentation strategies for the documents, and
provide a ‘catalogue of assets’. The layers shown are independent of the exact
design method used, and may work with either an object-oriented or
entity-relational approach. The two greyed areas of missing ‘cement’ are needed
to couple the organising principle of the web site with the semantics within
the texts and with the objectives of the presentations.
Previous work on
the use of knowledge tools to support hypertext by Nanard
et al. [33] set out the requirements
for a hypertext design environment, recommending that tools are required for
generalising and instantiating knowledge models, to enable designers to
alternate between bottom-up and top-down approaches, thus promoting both
structuring and updating activities.
We suggest that
the knowledge modelling work of the Semantic Web could be exploited by applying
ontologies not only as an organising principle for documents, but also to
describe the interrelationships between concepts embedded in the document
content. The model could also expose these concepts (and the structure of their
inherent relationships) whilst documents are being written or read.
We suggest that
there are many benefits to be had from extending the scope of the design
activity from simply dealing with the web site ‘templates’ into dealing with
the semantics of the content. The availability of this design framework at:
- authoring time will support authors
with appropriate knowledge for constructing texts (i.e. narrative and rhetorical material) and the relevant links
between them
- reading time will support readers with
adaptive and context-sensitive information delivery and linking
techniques.
7
Concluding Remarks
The objective of
hypermedia design models is to produce a well-organised web site. This paper
has elaborated the problem of modelling the semantics within text using current
design models and methodologies. While the hypermedia models are used to
provide the macro-structure of a web site (provide site design and navigation
features at the level of the document, unit or Web page), they fail to identify
the interconnected semantic fragments contained within the text.
Many of the
methodologies and models used in web design take a simple layered approach,
separating the design issues so as to allow independent implementations. These
fail to provide a method of mapping from one stage to the next, that is, they
lack ‘cement’. Treating links as first class objects has provided a means of
joining the navigational layers and presentation layers, through adaptive,
contextual, and narrative linking.
Similarly, Semantic
Web knowledge models (ontologies) can be used to ‘cement’ the domain and the
navigational analyses, not only by providing the relation between different
content units but also by making explicit the relationships between the
semantics within the text. As a result, designers can extend their influence
into the texts to influence the production of semantic content.
This approach to
extending the existing design models was born out of the experience of using
the models described in section 2 in large industrial hypermedia projects, in
running a Web Design undergraduate course, and in the authors’ research
activities into the Semantic Web [1]. Elements of a large website for a current
project (the Virtual Orthopaedic European University (VOEU), http://voeu.ecs.soton.ac.uk/) have been built using this model. Further
work is underway to instantiate the abstract model (Figure 3) and requirements
listed here into a generalised Web design model supported by appropriate tools,
with a full case study.
8
Acknowledgements
This work has been
funded in part by the Writing in the Context of Knowledge project funded in the
9
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