Rogerio Bittencourt⁽¹⁾, Marco Antonio Pinheiro^(2)
(1)(2)Universidade do Vale do Itajai - Sao Jose. Brazil

	[New Technology]	[Health Informatics]	[Physical Therapeutics & Rehabilitation]

3. A Project Methodology for Hypermedia application - OOHDM

Unlikely reference models, the project methods for developing hypermedia applications are concerned about the conceptual modeling of the application domain. In some references, they are called authorship models. This work intends to analyze OOHDM only. ^(5,6)

According to ^(7,8), the OOHDM is a method concerning the development of hypermedia applications which describes the tasks to be done since the application domain analysis until its implementation. It is an evolved version of the HDM, comprising a series of new concepts mainly coming from object orientations.

⁽⁷⁾, says that the OOHDM suggests the development of hypermedia to be a process divided in four steps, as long as they don´t follow the cascade development model, but a combination of interactive, incremental and quick prototyping models. The steps of the method are: conceptual modeling, navigation modeling, interface abstract project and implementation.

3.1 Conceptual Modeling

According to ⁽⁵⁾, the main goal of this step is to build an application domain model represented by a scheme called Object-Oriented Hypermedia Modeling Scheme, in which the main primitives are: class, object, subsystem and relation. The concepts present in this modeling are very similar to the ones in the object orientation, however enriched with other ideas, such as: subsystems and qualities perspective. In the conceptual modeling it is possible to observe a greater concern about the objects structure than about their behavior.

For ^(7,8), a documentation instrument often used by OOHDM are the cards. They are used for classes, relation and subsystems reporting, and each kind of card holds particular features for reporting each kind of primitive. The main reason for using the cards is its easy handling.

An example of conceptual model can be seen in figure 1.

Figure 1 - An application conceptual scheme about painters and paintings.

Source: ⁽⁷⁾

3.2 Navigation Modeling

According to ^(7,8), in this step a model is built from the conceptual scheme created in the previous step, however it is concerned about presenting the application navigational aspects, based on users´ profiles and on tasks to be supported.

This new model is a vision of the domain model by the point of view of how the information organized and connected to the hyperdocument will be obtained.

⁽⁸⁾ says that different navigation models can be created from the same conceptual scheme. This happens when more than one application about the same domain, although for different users´ groups or to hold different kinds of tasks to be supported is needed.

The main products of navigational modeling are: the navigation class scheme and navigation context distinction. The node classes, the link classes, the access structures and the navigation contexts that compose the hypermedia application are defined in these products.

⁽⁷⁾, states that the nodes, for the OOHDM, are described as visions of objects that belong to the domain classes. A node class is described by the domain classes from which it has been created, by its qualities and link classes which it is related with. They can be a direct mapping of a domain class or a feature combination of different conceptual classes as seen in figure 2.

Figure 2 - OOHDM navigation classes scheme.

Source: ⁽⁷⁾

According to ⁽⁷⁾, unlikely the conceptual scheme classes, the node classes do not hold multiple perspectives. Thus, during the creation of node classes, different qualities or classes must be created so that there will not be multiple perspectives.

3.3 Interface Abstract Project

According to ⁽⁵⁾, after defining the navigational structure, it is necessary to specify how the navigational elements are perceptible to the user and which events cause changes to the information introduction.

The goal of this step is to build an interface abstract project concerned about specifying the application dynamic behavior, considering the introduction aspects, including information formatting (texts, tables, etc.), definition of sensible events by the interface as well as its implications.

The separation between the navigation modeling and the interface abstract project allows many interface projects to be built from the same navigation model, introducing each of the different interface aspects to the same navigational definitions. The separation also avoids the inclusion of issues related to interface change in the navigation model. Only navigational changes are represented.

⁽⁷⁾, states that the OOHDM uses the ADVs (Abstract Data View) model to specify the interface abstract project of a hypermedia application. The ADVs are objects with a state and an interface, and the interface changes can be done through regular functions, call to procedures or by created events. The ADVs are abstract because they do not specify implementation issues however they hold a state and an interface. Another important concept is the ADO´s (Abstract Data Object) that can be seen as structured information containers and that are considered ADVs that do not support interface events. An ADV may present data from one or more ADOs and one ADO can hold the reference of one or more ADVs.

As seen in figure 3, the ADV charts specify the transitions that occur after the created events besides presenting the possible states for an ADVs. For each transition, it is necessary to specify the event that must occur to the state entrance, the entrance pre-condition and the entrance post-condition. An often-used variable to express such conditions is the perception Context that indicates the interface elements and ADVs which are perceptible for the user.

Figure 3 - ADV chart example.

Source: ⁽⁷⁾

3.4 Implementation

According to ⁽⁵⁾, two platforms for implementing the applications modeled with OOHDM are pointed. The first one is based on using a traditional hypermedia ambient and the second one, on using a object-oriented ambient of general purpose.

⁽⁸⁾, states that in the first case, there´s a mapping that consists basically in converting the navigation class instances in nodes that have a similar behavior to the one described in the abstract data project. The problem lies in the data model of traditional hypermedia systems which are based essentially on nodes and links, while many concepts originated from object orientation are present in the OOHDM.

The ADVs can be easily implemented and data objects can be separated from interface objects. The problem is providing codes, mainly to describe the introduction layers and the navigational behavior found in hypertexts. ⁽⁵⁾

Discussion Board

Any Comment to this presentation?

[ABSTRACT] [1. Introduction] [2. Multimedia, Hypermedia and Hypertext Concept] [4. Auditory Training] [3. A Project Methodology for Hypermedia application - OOHDM] [5. System Description] [6. Conclusion] [Annexes] [BIBLIOGRAPHICAL REFERENCES] [Discussion Board]

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	[New Technology]	[Health Informatics]	[Physical Therapeutics & Rehabilitation]

Rogerio Bittencourt, Marco Antonio Pinheiro
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Last update: 16/01/00