Web Site Development Methodologies - High Level Models and Methodologies for Information Systems - page 67

Table 4.1 The four-stage OOHDM (adapted from Schwabe and Rossi 1995a )
Stages Products Mechanisms Design concerns

Conceptual
design

Classes Classi cation Modeling the semantics

of the application domain

Subsystems Composition

Relationships Generalization

Attribute
perspectives

Specialization

Navigational
design

Nodes Mapping between con-

ceptual and navigation
objects

Takes user pro le and
task into consideration

Links
Access
structures

Emphasis on cognitive
aspects

Navigational
contexts
Navigational
transformations

Abstract inter-
face design

Abstract inter-
face

Mapping between naviga-
tion and perceptible
objects

Modeling perceptible
objects
Implementing chosen
metaphors

objects

-

Responses to
external events

Interface
transformations

Describing interface for
navigational objects

Implementation Running

application

Those provided by the
target environment

Performance
completeness

described in the conceptual model are corresponded to different navigation classes.
OOHDM posits that navigation objects are the concrete components that give form
to conceptual objects. Likewise, links also re ect conceptual relationships. The

resulting schema, specifying all navigational classes, de

nes the navigational
domain of the hypermedia application. The actual structure of the navigational
design is then developed (Schwabe et al. 1999 ).
The third stage is abstract interface design, where an abstract interface model is
developed by identifying perceptible objects (such as a picture, a city map ) and

interpreting them in terms of interface classes. Interface classes are described as
aggregations of primitive classes (such as text

…

fields and buttons). Because user
interface is a fundamental aspect of Web development, it is also an essential stage
of the OOHDM process. The abstract interface speci cation will determine the

appearance of navigational objects, which objects will activate navigational actions,
the synchronization between multimedia elements and the context and purpose of
interface transformations. This is achieved by means of Abstract Data Views,
formal models that describe structural as well as interactive aspects of the interface
(Schwabe et al. 1999 ).
The fourth and final stage is implementation, and it essentially entails the run-

ning of the application. A particular attention is now given to the runtime envi-
ronment. Schwabe et al. ( 1999 ) outlined an appropriate environment named