Deferred system's design: Situated system requirements gathering with Hyper-Tmodeller

AI & Soc (2001) 15:316-343 �9 2001 Springer-Verlag London Limited A~I I~ ~ 0 ~ 1 [ll~'~q

Deferred System's Design: Situated System Requirements Gathering with Hyper-Tmodeller

Nandish V. Patel Department of Information Systems and Computing, Brunel University, Uxbridge, UK

Abstract: The conceptual foundations underpinning the approach to system requirements gathering considered in this paper are deferred system's design and tailorable information systems. In this approach users of information systems are regarded as active developers. System requirements gathering is considered from an interpretative and situated perspective using the Hyper-Tmodeller CASE tool. The tool enables better interpretative and situated system requirements gathering, through visual modelling by users and professional system developers. It is designed to address the requirements communication gap between system analysts, designers and eventual users.

Keywords: Deferred system design; Hypermedia; Hyper-Tmodeller; Modelling; Situated systems development; Tailorable information systems

1. Introduction

The gathering and management of system requirements information is both an important and problematic issue in information system (IS) development. It is a process consisting of collecting, organising, displaying, interpreting and applying requirements information to IS development. This process requires communication among different stakeholders such as management, systems developers, and users, which is problematic in system development terms. This is especially the case during system requirements gathering. Recent developments in prototypical system development (Pressman, 1997) have not alleviated problematic communicative processes between developers and users.

Previous relevant research on requirement gathering may be categorised into four phases: tradit ional methods, user par t ic ipat ive methods, and end-user computing and evolutionary methods. Traditional, participative and evolutionary methods encourage users to participate in system development, but they assume that users are technically competent to do so. The user participation research into system development tends to include users as non-professionals aiding in

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the methodological development processes, but they are not enabled to make actual system design decisions. The user participation research is clearly important, as it increases the acceptability of delivered systems by users. Mumford's (1993) work in participative research has focused on social and ethical issues. However, all these approaches share the premise that it requires technical expertise to develop IS, and while they encourage users to participate in system development, they do not actually enable it.

A related area is studies into user-centred system development, which is a prominent thread in IS development (see Norman and Draper' s, 1986, classic). A criticism that could be levelled at some of the research undertaken under the banner of user- centred systems development is that there has been little research that enables users to make system design decisions. As such it can be difficult to explain why delivered systems often disappoint their users, are underused, or even fail to be used. User- centred research and research into the social and ethical issues in IS, such as Mumford's (1993), ignores the situated aspects of systems design (for details see the classic work by Suchman, 1994), which is explored in the present research.

The research reported here extends the work in participative research by seeking to enable users to design and develop systems themselves. Little basic research has been undertaken in the area of users doing IS design and development on an ongoing basis in the context of their work. Such research is pertinent in modern businesses, where external and internal business processes are likely to change. Consequently, personal and organisational information and knowledge needs change too.

Some recent research challenges aspects of the philosophical foundations of systems analysis and poses the challenge of fresh thinking on the communicative processes in IS development. Suchman (1994) shows how situated aspects are important to consider in computer-based systems and Walsham (1995) describes how interpretation is an issue in IS research and development. Such works pose a number of problems in system requirements processes. One, how can analysts' and users' ideas of IS be objectified and communicated? System analysts' internalised behaviours of working need to be made transparent to users, as do users' ideas of what kind of IS they need. Two, how can the contextual, situational and social features of a proposed IS be captured? Three, how can interpretations of IS be reflected during the tS development process and in the developed IS?

A CASE tool called Hyper-Tailorable-Modeller, or simply Hyper-Tmodeller (pronounced Hyper-T-modeller), is being designed to bridge the communication gap between systems designers and users, while addressing contextual, situational and interpretative issues in IS development. Patel (1999a) has discussed the conceptual foundations of Hyper-Tmodeller, which is a hypermedia system for better system requirements gathering. Hypermedia systems are especially useful in modelling real- world complex situations because of their flexible and dynamic nature (Nielsen, 1990). In Hyper-Tmodeller, the IS to be developed is modelled by users and analyst, and by their interaction through tailoring the model of IS developed. Hyper-Tmodeller enables recent changes to requirements, organisational context, work situation and business processes to be identified, and through dynamic remodelling it updates systems specification. The ability of Hyper-Tmodeller to dynamically remodel and update a specification is especially important in systems development affected by changing system requirements.

318 N.V. Patel

In this paper, the development of Hyper-Tmodeller is described. Requirements information organisation, storage, access and retrieval issues in Hyper-Tmodeller are discussed. To understand the role of Hyper-Tmodeller in IS development, the notions of deferred system design and tailorable information system are presented in Section 2. An overview of Hyper-Tmodeller's modules is provided in Section 3, where information organisation and storage issues, and information access and retrieval issues, are discussed. In Section 5 Hyper-Tmodeller's design specification is given and discussed. A broad discussion is developed in Section 6 of the current research and its implications for theory and practice. Some conclusions and avenues of future work are presented in Section 7.

2. System Tailorability

The notion of systems tailorability is discussed in this section because it leads to improved system requirements gathering. Both deferred system design and tailorable information systems provide the context in which Hyper-Tmodeller is being developed and brief overviews are provided. Systems tailorability is a conception of IS development and usage in organisations where knowledge of requirements is uncertain, possibly even non-existent or subject to change. Given organisational change, it is necessary to enable tailoring of IS by systems professionals (termed macro-tailoring) and by users (termed micro-tailoring). Empirical data confirms the need for both kinds of systems tailoring (Patel, 1999a). The notion of systems tailoring is built on the deferred system design approach, which is explained next.

2.1 Deferred System Design

As well as distinguishing between IS and users, current models of systems development distinguish between the development process and actual usage. Most requirement engineering is concerned with establishing a system specification to inform subsequent design and implementation. This is also true of newer systems development approaches such as the process view (Warboys, 1991). Little real consideration is given to the actual usage of developed systems in those approaches.

The phase of system requirements determination in current software development models is often superseded by organisational events (Baskerville et al., 1992). These events are changes to business objectives, policies, procedures and process, which means that users' need for information changes too. Designing IS purely on the basis of establishing requirements first results in IS that tend to dissatisfy users and reify organisational behaviour. Often the result is the use of systems in other ways than intended or planned or sometimes not being used at all. Most critically, the approach results in organisational work being moulded around the delivered system, rather than the system facilitating changing and ongoing organisational work designed to achieve business objectives and success.

Deferred system design is a radically and fundamentally different approach to software development and usage. The distinction between the development process and actual usage, and therefore between the IS and user, does not prevail in deferred system design. Instead, IS development is treated as a changing and ongoing activity,

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where so-called users are developers too. As such, this approach concurs with the living systems argument proposed by Paul (1993).

Deferred system design is the view that users themselves should be able to design IS for organisational situations and the change they encounter. It emerges from Patel's (1999b) study that planned IS are actually developed and used in a changing and ongoing organisational environment.

The concept of deferred system design may be extended into an IS design principle. The principle is named deferred system design decisions, and is embodied in Hyper- Tmodeller. This principle is the view that IS should be designed in such a way as to enable users of IS to make the actual systems design decisions, allowing the organisational situations and context in which IS will be used to be captured. The principle thus accommodates interpretative and situational aspects of IS.

The notion of deferred system design decisions is analysable into the sub-concepts of: organisational variability, user control, systems functionality, systems usability and user interfaces. By providing user control over these components of IS, aspects such as the human-computer dialogue, inputs and systems functionality can be tailored by users to suit situational needs and so cater for organisational change.

Deferred system design seeks to cater for emergent properties of IS (see Section 2.2 for details). Information requirements have a contextual and situational aspect which current models for establishing information requirements do not recognise. It is these contextual and situational properties of information that deferred system design seeks to address, and which Hyper-Tmodeller seeks to capture in tailorable models of IS.

Developing systems on the basis of deferred system design would reduce the emphasis on establishing a complete set of requirements before commencing development. IS developed using the principle of deferred system design decisions would be contextually sensitive, situated and interpreted. In practical terms, it is possible to incorporate the contextual, situated and interpretative requirements into tailorable IS, which emerge from such requirement gathering, as explained in the next section.

2.2 Tailorable Information Systems

The notion of tailorable information systems (Patel, 1998) is relevant in today's organisations that have to deal constantly with business process change. It concurs with Suchman (1994), who argues that intelligent computer systems designs should consider the non-planned nature of most human behaviour, which she calls 'situational actions'. She asserts that human behaviour is more accurately explained as situational action, where humans react to actual or perceived situations rather than behave according to plans formulated in advance. In changing organisations, the notion of making IS tailorable by users allows for such situational action.

Probert (1997) supports the view that the distinction between developing and using IS is actually blurred, and concurs with the view that IS should be made tailorable. In considering the suitability of tailorable information systems in a new paradigm for IS research, Probert (1997) comments that the 'objects' in systems tailorability research are intertwined between technical and social aspects. In such situations, the tailorability of an IS is an emergent property, determined by the possibilities (and constraints) of the technology and social arrangements.

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In regarding IS development and usage as a continuous process, as in tailorable information systems, it is possible to encourage flexibility in system's design, and at the same time improve relevance, acceptance and life expectancy of IS. This is possible because the principle of deferred system design decisions is sensitive to organisational change (see Stamoulis et al., 1996, for proposed systems architecture for tailorable information systems).

Tailorable information systems require tailoring mechanisms. It may be useful to view systems tailorability as a hierarchy. The hierarchy is a valuable concept for analysing the principle of deferred system design decisions into components to aid development of tailoring tools. For instance, at the top of the hierarchy is the idea of living information systems (see Paul, 1993, for details). The subsequent levels, such as deferred system design and system's control, are stages that move towards realisation of active user participation, until the bottom level is reached, where practical software mechanisms such as Hyper-Tmodeller are achieved. For an example of related work in tailorable computer systems see Malone et al. (1995).

The discrete activities of systems analysis, design, development and implementation that are found in current software engineering paradigms become unnecessary in tailorable information systems. Patel's (1999a) empirical data shows that the linear progression from analysis to design to systems construction was not possible in the four cases studied. It failed to account sufficiently for the organisational changes taking place. By completing these phases as discrete events, systems professionals were reluctant to consider alterations to design arising from organisational change such as changes to business objectives, policies or procedures.

The study also shows that users of IS carried out a form of continuous analysis, design, development and implementation when they used spreadsheets for processing student data, data-mining tools like Explorer or set their own sales analysis codes for sales purposes. This may be regarded as a form of systems tailorability. Such variations caused by organisational change were met by using information technology flexibly to meet changing information needs.

3. Background to Hyper-Tmodeller

Hyper-Tmodeller manages the hypermedia storage of systems development documents, specifically system requirement information. The models created in Hyper-Tmodeller are active models that are enactable in terms of leading to concrete system specification. These models create users' system requirements documents. The purpose of the current research is to further progress Hyper-Tmodeller beyond the idea stage proposed in Patel (1999a), where a fuller description of the modules in Hyper- Tmodeller is available. In this section an overview is provided. Figure 1 shows the model for the research,

The aim of the research is to develop a dynamic and enactable IS modelling tool that can be used for eliciting user requirements during systems development (see Warboys et al., 1998, for a discussion of enactable models). The main issue to be addressed is how contextual, situational and variable requirements information can be dynamically captured, organised, stored, retrieved and accessed in a way that reflects users' interpretations of information, organisational context and situated


Research in the use of Hyper-TMcdel[er for

eliciting user requirements during

systems development

Hyper-TM .od.eEler design~

Fig. 1. Research model for Hyper-Tmodeller.

aspects of work. This is shown on the left-hand side of Fig. 1. Once this is understood, it can be incorporated in a specification for designing Hyper-Tmodeller, which is shown on the right-hand side of Fig. 1. Both these aspects are reported in this paper.

3.1 Hyper-Tmodeller's Basic Modules

Hyper-Tmodeller enables active user participation in the system development process. The system provides the user with a number of graphical and documentation tools that they use to model their current work or wider business processes. Hyper-Tmodeller consists of modules that perform specific functions. Each module is briefly outlined in Table 1.

The models of IS created may be regarded as similar to the AS-IS models or TO- BE models in business process modelling (Warboys et al., 1998), or the users can begin with AS-IS models and develop these into TO-BE models in the Discovery- Designer module. The actual management of system requirement information in these modules is discussed in depth in the following sections.

3.2 Information Organisation and Storage

This section discusses information organisation and storage issues in Hyper-Tmodeller. Gathered system requirements information can be stored in a hypermedia database in a number of ways. Such information can be stored as frames as in Akscyn et al.'s (1988) Knowledge Management System or as objects (Hofmann et al., 1990; Wuwongse and

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Table 1. Hyper-Tmodeller's modules.

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Originator-Creator module

Discovery-Designer module

Text

Diagrams

Policies and issues

Tailorable Information Systems Analyser

Logographer

The initial tailorable model of a proposed IS is created by the analyst in the Originator-Creator module. Users, to suit their perception or interpretation of what they think is happening in their workflow, can then build upon this initial model. Alternatively, a user or multiple users can build an initial model from scratch themselves, which is then further developed by analysts

This module provides the user with a variety of tools to manipulate the initial model created in the Originator-Creator module. For example, users can create, modify or delete links or objects in the initial model where they feel necessary, thus developing a sense of context and situatedness of information requirements

Text is used for adding comments to the model, documentation or making annotations. It can also be used to make suggestions and to communicate with the analysts. This facilitates both the situated and interpretative aspects of IS

Users use the diagramming module to create images or models of their work situations. Diagrams allow users to more clearly communicate their ideas to others, so misunderstandings are minimised. Visual modelling is a useful communicative device

Business policies and issues are implemented as links in Hyper- Tmodeller. There are four links identified by the author: procedural, process, causal and policy

This module collects all the designed material and alterations from the Originator-Creator and Discover-Designer modules to form a consolidated version of the current model for the proposed tailorable information system. It represents the present work situation, which users can amend further in the Discovery-Designer module

The logographer acts as a documenter that documents all the action performed in the Originator-Creator and Discovery-Designer modules. The logographer also collects all text comments made by users, forming documentation of a modelling session that incorporates system requirements

S ingkorapoom, 1991). These in fo rmat ion m a n a g e m e n t techniques are sui table for deferred

system des ign b e c a u s e they e n a b l e i n f o r m a t i o n to be r e t r i eved for ta i lor ing purposes .

T h e r e are a n u m b e r of i m p o r t a n t i ssues w i th r ega rd to the o rgan i sa t ion of i n f o r m a t i o n

tha t m u s t b e a d d r e s s e d by H y p e r - T m o d e l l e r . Fi rs t ly , m u l t i p l e users c an use H y p e r -

T m o d e l l e r c o n c u r r e n t l y . It m u s t t he r e fo re b e ab le to p r o v i d e an e n v i r o n m e n t for users

to work in whi l e also conso l ida t ing cur ren t ve rs ions of work. Secondly , H y p e r - T m o d e l l e r

m u s t b e ab le to s tore l a rge a m o u n t s o f i n f o r m a t i o n o f v a r y i n g types . A s des igns o f the

IS b e i n g d e v e l o p e d b y the users e v o l v e ove r t ime, the size o f the i n f o r m a t i o n r epos i to ry

wi l l inc rease . F u r t h e r m o r e , H y p e r - T m o d e l l e r is a h y p e r m e d i a s y s t e m and t h e r e f o r e

m u s t b e ab le to s tore i n f o r m a t i o n in the f o r m of text , g raph ics , v i d e o and sound .

Th i rd ly , s to r ing i n f o r m a t i o n in a m a n n e r tha t is i n d e p e n d e n t o f the va r ious app l i ca t i ons

u sed to m a n i p u l a t e t h e m wil l p r o v e to b e useful .

H y p e r - T m o d e l l e r p r o v i d e s t a i l o r i n g a n d d i a g r a m m i n g too l s t ha t e n a b l e use r s to

c r e a t e a n d m a n i p u l a t e d i a g r a m s , m o d e l s a n d i n f o r m a t i o n s to red in the d a t a b a s e . I t

w o u l d b e u s e f u l i f u se r s w e r e ab l e to u s e o t h e r d i a g r a m m i n g a n d e d i t i n g too ls to

w h i c h t h e y w e r e m o r e a c c u s t o m e d to t a i l o r t he i n f o r m a t i o n s t o r e d in H y p e r -

T m o d e l l e r ' s d a t a b a s e .


3.2.1 Local and Global Storage

Hyper-Tmodeller seeks to create models or representations of work situations. This requires a number of users and analysts to work collaboratively when modelling the business environment. Each user may have his or her ideas, designs or points of view to add to the current design or model. As a result, there may be several versions of a design in the system at any one time. This highlights the need for a separate work environment for each user and a separate storage environment to allow for version management.

Hofmann et al. (1990) provide a useful architecture that helps cater for this. Their article discussed the use of hypermedia for knowledge acquisition during the development of expert systems. Their system architecture can help Hyper-Tmodeller manage information used by a number of different users. Their CONCORDE system consists of two environments: a global hypertext and a local context. The global hypertext contains all the information that is common to all users in the system. The local context contains information copied from the global hypertext. This information is available to a number of users and is manipulated in the local context through the use of a number of drawing and editing tools. The local hypertext also has a local manager to manage the information and a local storage area where an individual user's work is held.

The global hypertext and local context used in the CONCORDE system can be viewed as being analogous to the Originator-Creator and Discovery-Designer modules respectively in Hyper-Tmodeller. The Originator-Creator module creates the initial model from scratch that can then be manipulated by users through the use of drawing and editing tools in the Discovery-Designer module. The primary idea is to maintain a separate area where information can be stored and an area where information can be manipulated by a number of users. This structure will aid in the management of cooperative work where the same information is accessed and worked on by a number of different users. Figure 2 shows the architecture of Hyper-Tmodeller incorporating the global and local hypertext idea referred to as the Originator-Creator (global) and Discovery-Designer (local).

The Originator-Creator module within Hyper-Tmodeller consists of an object manager, a set of design tools and an object storage area. The object manager is used to manage the information created in the Originator-Creator module. The object storage stores the initial model created and the current version of the proposed tailorable information system. The object manager commmficates with the local manager in the Discovery-Designer module. The local manager extracts a copy of the information required by a user from the object storage and places it in a local work area in the module for the user to work on. Each user may have different ideas to add to the model and as a result many different versions of the model may be created. This raises the need for a local storage area where each individual's work can be stored.

Hyper-Tmodeller stresses the need for end-users, managers and analysts to work together when developing IS to improve the development communicative process. Teamwork and collaboration therefore play an important role. Hyper-Tmodeller enables users to create their models of work situations and to also view and make additions to other users' work. This is similar to a group of engineers working

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Discovery-Designer module

Local manager

Editing tools

information copied from the Originator-Creator storage area

Local storage

Communication

Originator-Creator module

Object manager

Design tools

@ Object storage

Fig. 2. The Discovery-Designer and Originator-Creator modules of Hyper-Tmodeller.

together when designing a plan for a building where everyone has his or her opinions and suggestions to add to the plans. Hyper-Tmodeller must provide a mechanism to consolidate the work of everyone involved in the development project. Furthermore, each user must be able to view other users' work and make comments or changes to them. This is done in the Tailorable Information System Analyser. It consolidates all the designs, configurations and tailoring done by users and produces a current version of the tailorable information system. This consolidation process is shown in Fig. 3.

The Tailorable Information System Analyser obtains all current work done by all users on the model from the local storage in the Discovery-Designer module. The newly amalgamated version is produced and stored in the object store in the Originator-

Discovery-Designer module Originator-Creator module

Object manager Local manager

Editing tools

Information copied from the Originator-Creator storage area

@ Local storage

Data request

Communication

design tools

@ Object storage

T Current version of

living information system 1

Result

Living Information Systems Analyser

Fig. 3. The Tailorable Information Systems Designer module of Hyper-TModeller,


Creator module where individual users can access and work on it. The architecture in Fig. 3 is an extension of Hofmann et al. 's (1990) architecture for CONCORDE.

Ideally, the Tailorable Information Systems Analyser module would be able to automatically consolidate the work of the various users and generate a proposed version of a tailorable information system. If technological constraints preclude this possibility, then the analyst in consultation with the users will do the consolidation. The analyst and users should be able to override or moderate consolidation decisions even if automatic consolidation was technically feasible. The Tailorable Information System Analyser module would provide a set of tools for the analyst to use when configuring a proposed version of a tailorable information system.

3.2.2 Hypermedia Engine

Users of Hyper-Tmodeller should not be constrained in using a particular set of tools or applications when tailoring models. Hyper-Tmodeller must enable users to use various applications to manipulate the information stored in the database. A hypermedia engine (Schutt and Streitz, 1990) provides for this by separating object storage management from the interpretation and display of objects. The hypermedia engine handles all the storage requirements for the objects. It simply stores an object and has no information about the editor or tools used to create and modify the content of the node. An application interface defines the content of the node. For example, the hypermedia engine may store a string that is interpreted by the application interface as plain text or a set of commands (Schutt and Streitz, 1990). The application interface layer also defines the links used in the system. Such links may vary and may reference only part of an object instead of the whole object. To do this, information is required about the internal structure of the object. Because the object is defined at the application interface layer, so too must the links in order to enable linking to various parts of the object. Figure 4 shows the architecture of Hyper-Tmodeller with the incorporation of a hypermedia engine and an application interface layer.

The Originator-Creator, Discovery-Designer and Tailorable Information Systems Analyser modules in Hyper-Tmodeller all use the same application interface layer to access, view and manipulate the objects stored in the database. Notice that there is now one set of tools provided in the application interface layer as opposed to a separate set of editing and design tools as in Figs 2 and 3. These tools consist of both the design and editing tools and are used by all three modules in Hyper-Tmodeller. The hypermedia engine consists of both the object manager and the local manager and resides between the database and application interface layer. The local and object managers are still kept separate and communication is maintained between the two. The separation of a global storage area and a local storage area is still maintained in the system.

This architecture is similar in some respects to the Dexter hypertext reference model (Halasz and Schwartz, 1994). The Dexter model consists of three layers: the storage layer, the run-time layer and the within-component layer. The storage layer describes the database of the hypermedia system. It does not describe the access, viewing and manipulation capability of hypertext systems. This is captured by the run-time layer and can be seen as being analogous to the application interface layer in Hyper-Tmodeller.

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Data request Result

Living Information Systems Analyser

Application-Interface layer

User interface

Hypermedia engine

Local manager ~ c . . . . . isat ion~--~ Object manager I

Information copied from the Originator-Creator storage area

Local storage

Object storage

Current version of living information

system

Fig. 4. The hypermedia engine and application interface of Hyper-Tmodeller.

3.2.3 0-0 Methods for Storage

The final issue remaining with regard to the storage issues of Hyper-Tmodeller involves the type of database that will be used to store the information obtained during systems development. Relational databases have been the most common method for storing information. Wuwongse and Singkorapoom (1991) characterise a hypermedia database in the following way:

�9 Nodes and links are the basic constructs of the system as opposed to records and files inherent in relational databases.

�9 A node can be treated as an object belonging to a certain object class instead of being composed by a set of attributes.

�9 Nodes can be linked in an unrestricted network.

�9 Browsing and navigating is an inherent capability of the system.

These characteristics suggest that an object-oriented database would be the most appropriate database for Hyper-Tmodeller. An object-oriented database is a system that provides database functionality such as storage, query, update and transactions (Spiers, 1991). Data is organised into objects and these objects can be organised into classes within hierarchies which enables the inheritance of some of the characteristics of parent levels (Woodhead, 1991).

The advantage of an object-oriented database lies in its ability to store many types of objects such as textual objects, graphics, video, sound and a combination of these (Woodhead, 1991). This characteristic of an object-oriented database makes it suitable for applications that make use of real-world objects such as knowledge- based systems (Spiers, 1991; Woodhead, 1991), global IS and hypermedia systems. The strength of an object-oriented database lies in its ability to represent real-world objects in its database. This concept of representing real-world objects is in keeping


with Hyper-Tmodeller 's goal to model the contextual, situational and interpretative aspects of IS.

As information in Hyper-Tmodeller will be stored as objects, it is necessary to consider the nature of such objects. Schutt and Streitz (1990) and Wuwongse and Singkorapoom (1991) introduce three basic objects in hypermedia systems: node objects, link objects and composite nodes. This idea is applied to Hyper-Tmodeller yielding the objects HTM_Nodes , HTM_Links and HTM_Compos i te_Nodes representing the nodes, links and composite node objects respectively. An HTM Node corresponds to a node in Hyper-Tmodeller. It is an object that holds a set of one or more interrelated information pieces (Wuwongse and Singkorapoom, 1991). Such objects are referred to as HTM_Objects in Hyper-Tmodeller. HTM_Links are objects that connect two existing HTM Objects. Links may exist between two HTM Nodes or between an HTM_Node and an HTM_Object within the same or another HTM_Node. An HTM_Composite_Node is a grouping of selected HTM_Objects. The HTM_Composite_Node contains all the features of an HTM Node object and extends it with the inclusion of components. The class structure of Hyper-Tmodetler 's objects are discussed in Section 5.

Wuwongse and Singkorapoom (1991) also add a 'hyperset ' object to the list of basic objects defined above. A hyperset object depicts a higher level of abstraction (i.e., aggregation and generalisation hierarchy). It is used for the representation of a 'map ' of the network of its interrelated components and is very useful in Hyper- Tmodeller with its abundance of information.

An object identifier uniquely identifies each object in Hyper-Tmodeller 's database. An object identifier is given to a newly created object and is used to reference that particular object (Dillon and Tam, 1993). Each object also has an author and a creation date (Schutt and Streitz, 1990). A history of each object is maintained in the database and hence can aid in version management.

4. Information Access and Retrieval

This section addresses the issue of information access and retrieval in Hyper- Tmodeller. The most common term used in hypermedia systems with regard to information retrieval includes navigation, browsing and searching (Nielsen, 1990; Woodhead, 1991; McKnight et al., 1991; Lucarella, 1990). Hyper-Tmodeller is designed to handle a large amount of information and it is imperative that users will be able to use this information efficiently and effectively. This means that users must be able to retrieve information by browsing through the information space and be able to search for specific information dynamically. This is especially important in terms of creating tailorable functionality in Hyper-Tmodeller, and would cater for the changing nature of requirements during systems development.

Browsing, navigating and searching are useful information access and retrieval capabilities and are specified in Hyper-Tmodeller. Hyper-Tmodeller enables users to explore their needs from a tailorable information system. In doing this, users are also able to learn more about how their business processes functions. While searching, the user does not wish to learn, but to look for a particular piece of information he or she already knows about and knows exists in the database. For

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example, the analyst may want to search for a data model in the database and may know what constitutes the data model in terms of its entities and relationships. The analyst merely wants to find the data model to see adjustments or tailoring made to them by other users.

4.1 Browsing and Navigating

Before discussing information access and retrieval for Hyper-Tmodeller , it would be beneficial to discuss the problems inherent in current hypermedia systems. The most cited problem with hypermedia systems is the ' lost in hyperspace ' problem (Nielsen, 1990; Fox et al., 1991; McKnight et al., 1991; Hammond, 1991; Littleford, 1991). The ' lost in hyperspace ' problem is especially evident in hypermedia systems with a large information storage capacity. This problem is characterised by users not having an understanding of the relationship within the system or not knowing their present location in the system (McKnight, 1991). Users may also have difficulty in finding specific information even if they know it exists in the system (Hammond, 1991). This problem is the result of poor search facilities and poor structuring of the information in the database. Finally, when the user simply wants to know what information exists in the database, he/ she would often browse the environment freely. Systems that provide multiple choices of information paths (i.e., moving f rom one node to multiple nodes) but minimum guidance will be of no benefit to such users (Hammond, 1991). It is imperative to take into consideration these problems when designing browsing and navigation mechanisms in Hyper-Tmodeller .

4.1.1 Navigational Maps

A navigational map gives the user a graphical overview of the information space. Ideally, it would 'pop ' up every time the user reads a hyperdocument and would accompany him during the reading process (Gloor, 1991). The map shows the user where he currently is in the information space. The user can also see where he can go from the current location. The idea of a map in hypertext is analogous to maps used by tourists to guide them through cities (McKnight et al., 1991). Implementing and displaying the map would become increasingly difficult as the size of the information space increases.

It would also be of great benefit if these maps could be automatically generated and updated. For example, if the user decides to create a link from one node to another or create a new node and link it to a current node, this would be reflected on the map immediately. It may be difficult, however, to generate satisfactory and comprehensible maps without understanding the contents of the document (Gloor, 1991). Figure 5 shows an example of the use of a map in Hyper-Tmodeller.

Figure 5 depicts a user currently viewing a data model created to date following Gloor, (1991). The map would automatically appear when the user accesses the hyperdocument. The greyed-out box (node) on the map represents the user 's current location in the information space. The user has the option of hiding the map by clicking on the 'MAP' button to hide and unhide the map. The map is displayed on a separate window that can be dragged around the screen so the worksheet or the map


Dataflow Dia ram for XX as at 9/9/99

Map Window

r e

Mr. White Mr. Black

D D

Fig. 5. The map window.

will not obscure the primary window the user is viewing. The map not only provides the ability for users to see where they are in the information space but also enables users to jump to another node by clicking on the desired node on the map window,

The map would become increasingly difficult to implement and display as the information space grows. Another method that can be used to cater for the problem of too much information would be to 'abstract ' the information displayed on the map (Bernstein et al., 1991). This technique is employed by Gay and Mazur (1991) in their 'Bughouse ' hypermedia program. The Bughouse program is a hype rmed ia p rog ram that contains in format ion on the subject of cul tural entomology. The map consisted of a Victorian farmhouse and each room in the house represented a topic. For example, the second floor consisted of topics on 'ar t ' and ' insects in commerce ' . To browse the house, the student simply selected a room to enter and the room was displayed along with additional information nodes represented by various items in the room (e.g., a plate or cookbook). Information about various species of bugs was organised according to theme. For example, if a cookbook in the kitchen room was selected, information relating to insects as food was displayed. The Bughouse hypermedia program made extensive use of graphical organisers.

The use of high-quality graphical organisers and metaphors was useful in organising information in the Bughouse program. However, it is the abstraction of the information that will prove to be of great benefit in Hyper-Tmodeller. Abstraction is a highly practised method in object-oriented modelling (Cattell, 1994) and also relational modelling (Tsichritzis and Lochovsky, 1982; Elmasri and Navathe, 1994). Depending on where in the information space the user is, the map would display information at a certain level of abstraction. Figures 6(a) and 6(b) show an example of how this works in Hyper-Tmodeller.

330 N.V. Patel

F igure 6(a) shows the map d i sp lay ing informat ion at a h igher level of abstract ion to the user. The user is cu r ren t ly v i ewing a da t a f low d i a g r a m s imi la r to the one in Fig. 5. The user now wishes to v iew in fo rma t ion wi th regard to Mr. Black . The user c l icks on the Mr. B lack ob jec t (bear ing in mind that the ob jec t in the workshee t can be nodes l i nked to o ther nodes wi th in the same w o r k s h e e t or in another workshee t ) and in fo rma t ion wi th r ega rd to that pe r son is d i s p l a y e d to the user as dep i c t ed in Fig . 6(b). The map w i n d o w in Fig. 6(b) now d i sp l ays i n fo rma t ion at a l ower l eve l of abs t r ac t ion where the cur ren t node is Mr. Black . Other nodes that Mr. B l a c k is a s soc ia t ed wi th are d i s p l a y e d in the map. The i n fo rma t ion on the map is now the re fo re spec i f i c to the node Mr. Black.

Dataflow Diagram for XX as at 9/9/99

Map Window

Datastore i~ I !.

Mr. Black

M r. White

D D D U D D

Mr, Black

Map Window

Mr. Black

E3 23

Fig. 6. (a) The map window displaying information at a high level of abstraction. (b) The map window displaying information at a lower level of abstraction.


4.1.2 Online Guidance

Online guidance and help facilities are imperative in all software systems. Help topics are the most common guidance provided in commercial software such as word processing and spreadsheet applications. Hyper-Tmodeller must provide help facilities to users and such facilities should be non-intrusive and context sensitive. Users should not be interrupted while working unless an error has occurred. Help facilities should also cater for the different level of users of the system.

In addition to help facilities, online guidance is used to lead the user through the complex information space (Boy, 1991) and provide suggestions about which links would be the most useful to follow (Croft, 1990). As readers navigate the information space, the system records their paths. Information regarding the user 's browsing pattern is stored in the database and is used to suggest other areas of exploration relevant to the topics already discovered. Boy (1991) terms this the system online advisor. When the online advisor is invoked, it will suggest other topics related to the topic already discovered by the reader such as 'the project team members ' , 'the project timeline' or 'other related projects'. The online guidance is similar to the map facility discussed previously in that they both provide the user with suggestions to navigate other relevant nodes in the information space. The primary difference lies in the presentation method employed by each. The map facility employs a graphical presentation whereas the online guidance employs a textual listing presentation.

4.2 Search and Retrieval

This section will address the issue of searching in Hyper-Tmodeller. Search facilities that can be employed by Hyper-Tmodeller include indexes and table of contents (Boy, 1991). Lucarella (1990) and Fox et al. (1991) also discuss integrating search and retrieval with hypertext that can be useful in Hyper-Tmodeller. Indexes are especially useful if they can provide contextual features too, as shown below.

4.2.1 Table of Contents

Hyper-Tmodeller 's users need a starting point each time they use the system that will enable them to navigate the information space effectively. The table of contents and indexes are the most common method employed by people when searching (Boy, 1991). The table of contents provides a useful starting point for users. The listings in the table of contents will comprise of links, each taking the user to various parts in the information space. As a number of users would be using Hyper-Tmodeller, each contributing their ideas to the design, the listing could be sorted according to users' names. It is appropriate that users can sort this list according to their preferences. Figure 7 shows how this could be achieved.

Figure 7 shows an example of a table of contents the user encounters when he accesses the system. The far left-hand column contains a number of folders. The first folder contains the consolidated designs performed in the Tailorable Information System Analysers. The remaining folders, listed alphabetically, contain work done by various users of the system. Items in each folder are listed in the right-hand side

332 N.V. Patel

File Edit View Tools Window Help

!,n ex II Tab'e~ IHe,p Exit ~ ~ con~nts ,~ ~

Design

Mr. Black

Mr. Pink

Mr. Brown

9/9/97

8/9/97

15/8/97

DFD for department X

ERD for department Y

Fig. 7. A simple table of contents in hyper-Tmodeller.

of the window. This list can be sorted chronologically or by subject by clicking on their respective buttons at the top of the window. The list also consists of links that upon clicking will allow the user to browse the information space. Each user 's folder contains his own work that is kept separate from other user 's folders and the consolidated design folder. This is achieved by maintaining a separate local and object storage area (Hofmann et al., 1990) discussed above in Section 2.2.1.

4.2.2 Indexes

indexes are aids that facilitate the location of objects (Bruza, 1990). The problem with indexes is that they often just provide the location of the keyword listed in the index but not the context in which it is used (Boy, 1991). This requires the user to examine several locations referred to by the index before finding the information needed. Boy (1991) and Bruza (1990) address this problem, stating that it is important to 'index in context'. This involves describing the object each index points to. For example, the index ' tyre ' could point to a number of information nodes. There could be other nodes describing how to 'replace a flat tyre', information about 'retreading', 'how to balance a tyre' or 'tyre manufacturers'. Boy (1991) and Bruza (1990) introduce the use of descriptors and locators in indexing. The descriptor is a description of the object or information node an index points to. The locator is a pointer to an object. The simplest descriptor is called the ' term' descriptor. A term descriptor is simply a keyword or a term. Examples of term descriptors are 'computers' and 'programming'. The disadvantage of the term descriptor is that it is not specific (Bruza, 1990). A ' term phrase' is an extension of the term descriptor and is more specific than a term descriptor. For example, the term phrase 'computer programming' is more specific than either the term 'computer ' or 'programming' alone (Bruza, 1991). Figure 8 shows an example of the use of indexing in context.

Deferred System's Design

I File Edit View Tools Window Help

! . ~ ii contents i Search Table of

=

k

Carburator Engine Flywheel Fanbelt Radiator

Vy re ] Windshield

Referent links

Balancing tyres Replacing a flat tyre Retreading tyres

u

Z

u

u

333

Fig. 8. Indexing in context in Hyper-Tmodeller.

In Fig. 8, the user brings up the index window by clicking on the ' index' button. The contexts of the index are listed alphabetically in the bottom part of the window under 'Referent Links'. The user may quickly jump to a particular part in the index list via the alphabet links on the top of the index window. The user has selected the index ' tyre' and the system returned three referential links: 'balancing tyres', 'replacing flat tyres' and 'retreading tyres'. The user may select one of the referent links provided depending on the context in which the user is interested in (Boy, 1991).

4.2.3 Search Engines

Search engines are commonly used to search large information spaces such as a library electronic catalogue system and the World Wide Web. The simplest and most common method of searching is the keyword search. There are, however, problems associated with this method of searching, such as the lack of specificity and users not knowing how to use them. For example, a user who wants to search for a topic 'How to perform calculations' may enter the entire text 'how to perform calculations' when instead he should simply enter the keyword 'calculations'. Furthermore, the use of general terms with poor filtering capabilities often leads to the retrieval of too much information. Conversely, the use of specific terms may be too selective, retrieving no information as a result (Lucarella, 1990).

Lucarella (1990) introduces a useful method of searching in a hypertext network. This method involves the use of predicates or inference rules. To illustrate how this method works Lucarella (1990)defines the following predicates:

334 N.V. Patel

Q(q,c): 'Query q is about the subject c'. D(d,c): 'Document d is about the subject c'. L(c,r): 'The subject c is linked to subject r ' . RC(d,c): ' the document d is relevant to subject c'.

The following retrieval rule involves a query about a single subject:

(Q(q,c) ? D(d,c)) ? RC(d,c)

The retrieval rule above states that if the query is about subject c (depicted by Q(d,c)) and the document d is relevant to subject c (depicted by D(d,c)), then the document d is deemed relevant to the subject c (depicted by RC(d,c)) and is retrieved.

The next retrieval rule shows how the search can proceed through the network to retrieve other relevant documents after executing the query above.

(L(c,r) ? D(d,r)) ? RC(d,c)

The retrieval rule above states that even if the document d is not about subject c (i.e., D(d,r) - document d is about subject r), it is still retrieved because there is a link from the subject c to the subject r (depicted by L(c,r)).

The two examples above show how the use of inferencing techniques can aid searching in hypermedia systems. The logic and mathematical concepts involved with this technique are fairly complicated and beyond the scope of this paper. Readers interested in this topic are referred to Lucarella (1990) for a more detailed discussion. However, such powerful search engines are clearly useful in Hyper- Tmodeller because the models of IS developed are freely and interactively developed by users and analysts, and access relevant systems design information requires power search engines.

5. Modelling Hyper-Tmodeller

This section provides and discusses the design specifications for Hyper-Tmodeller. Four design models were constructed for Hyper-Tmodeller:

�9 Jacobson's use case diagram;

�9 Gane and Sarson's data flow diagram;

�9 Rumbaugh's class diagram; and

�9 Rumbaugh's object diagram.

The design models in this section address only the information-handling issues discussed in this paper. The Jacobson use case diagram and the Gane and Sarson (1979) data flow diagram models all the information-handling issues discussed above. Rumbaugh's (1991) class and object diagram models the object-oriented method for storage issue discussed in Section 2.2. The following four sections discuss the models listed above as applied to Hyper-Tmodeller.

5.1 Use Case Diagram

A use case diagram defines what exists outside the system and what should be performed by the system (Jacobson et al., 1992). The next section provides a brief description of


the use case d iagram and the notations used, fol lowed by a descript ion of the use case model of Hyper-Tmodel ler . A use case d iagram shows a conceptual view of the relat ionships between the users and the operations performed by each of them.

A use case d iagram is a model of actors, a set of use cases enclosed by a system boundary , communica t ion associat ions be tween the actors and the use cases, and genera l i sa t ion among the use cases. The notat ions used within this document for use case d iagrams are taken from Jacobson et al. (1992).

5.1.1 Use Case Diagram for Hyper-Tmodeller

The use case scenar io of H y p e r - T m o d e l l e r in Table 3 models only the informat ion- handl ing issues addressed in this research (i.e., in format ion organisa t ion , s torage, access and re t r ieval) . Obv ious ly , there are many other opera t ions that can be pe r fo rmed on H y p e r - T m o d e l l e r such as pr int ing and user interface opera t ions (e.g., drag and drop, copy and paste); however , these operat ions are deemed to be outs ide the scope of this paper . There are two types of actors shown in the use case scenar io: the ana lys t and the user. Both the user and the ana lys t per form some opera t ions (use cases) and some are pe r fo rmed by ei ther one or the other.

Use cases re la t ing spec i f i ca l ly to the user inc lude 'pose r equ i remen t s ' , 'mod i fy m o d e l ' and ' s tore i nd iv idua l ' s work ' . Use cases re la t ing spec i f i ca l ly to the ana lys t inc ludes ' c rea te ini t ial ta i lorable mode l ' , ' c rea te consol ida ted vers ion of the mode l ' and ' s to re current vers ion of the m o d e l ' . The use cases 'V iew m o d e l ' , 'B rowse / Nav iga te in format ion space ' and 'Search in format ion space ' re la te to both the user and analyst . Tab le 2 p rov ides a descr ip t ion of the actors and Table 3 of the use cases.

5.2 Data Flow Diagram

A m o d e l l i n g se s s ion in H y p e r - T m o d e l l e r is shown in Fig . 9. The da ta f low d i a g r a m dep i c t s the f low of da ta and the w o r k or p r o c e s s i n g p e r f o r m e d by H y p e r - T m o d e l l e r . The re are va r ious s y m b o l i c no ta t ions i n t r o d u c e d by d i f f e ren t au thors and expe r t s ( W h i t t e n et al . , 1994). The C h r i s t o p h e r Gane and Tr i sh Sa r son da ta f low s y m b o l set (Gane , 1989; Gane et al . , 1979) is one o f the mos t p o p u l a r no ta t ions . A n a l t e r n a t i v e d a t a f l o w d i a g r a m s y m b o l set is the Tom D e M a r c o and /o r Ed Y o u r d o n s y m b o l set ( D e M a r c o , 1978). The da ta f low d i a g r a m used to m o d e l the m o d e l l i n g se s s ion in H y p e r - T m o d e l l e r e m p l o y s the Gane and Sa r son da ta f low s y m b o l set.

Table 2. Roles in Hyper-Tmodeller.

Actors Description

Analyst

User

The analyst is responsible for gathering user requirements, creating an initial tailorable model for users to work on and consolidating all users' work to produce a current version of the tailorable information system model

Users communicate requirements to the analyst. The initial tailorable model created by the analyst is modified by the users where required and this modified model is stored in the users' local storage space.

336

Table 3. Use cases in Hyper-Tmodeller.

N.V. Patel

Use case Description

View model

View initial model

View user's model

View current version of tailorable model

Modify model

Create consolidated version of the model

Create object

Delete object

Modify object

Add annotation

Store current version of tailorable model

Browse/Navigate information space

View navigational map

Access online guidance and help

Store individual's work

Search information space

Access search engine

View table of contents

View index

Performed by the analyst and the user. There are three 'extend' relationships associated with this use case. Viewing a model can be extended to include 'viewing the initial model', 'viewing user's model' or 'viewing the current version of the tailorable model'

Viewing the initial tailorable model created by the analyst

Viewing an individual user's version of the tailorable model. The viewer can only view other users' work and not make any amendments to them

All users' work is collected and consolidated by the analyst to produce a current version of the tailorable model. The user can then view this model

Performed by the user. This use case involves making changes to the tailorable model where the user feels is necessary. This use case 'uses' four other use cases: create object, delete object, modify object, and add annotation

Performed by the analyst. Involves gathering users' work and consolidating it to produce a current version of the tailorable model. This use case 'uses' four other use cases: 'create object', 'delete object', 'modify object', and 'add annotation'

Performed by both the user and analyst. Involves creating a new object in the tailorable model

Performed by both the user and analyst. Involves deleting/removing an existing object from the tallorable model

Performed by both the user and the analyst. Involves making changes to the tailorable model

Performed by both the user and analyst. Involves adding notes into various parts in the model to serve as an explanation of an object, design decision or as a message to others involved in the modelling process

Performed by the analyst. The emxent version of the tailorable model is stored in the global storage area in Hyper-Tmodeller for other users to retrieve and work on

Performed by both the user and analyst. This use case involves the user browsing the information space in no predetermined order. This is usually done to discover what information is stored in Hyper-Tmodeller and to learn the content of Hyper-Tmodeller. This use case 'uses' two other use cases: 'view navigational map', and access 'online guidance and help'

Performed by both the user and analyst. The navigational map is viewed during browsing to show the user where he/she currently is in the informationspace

Performed by both the user and analyst. The online guidance is used to provide suggestions about relevant links that the user can follow. The help facility is used to help the user use the system

Performed by the user. Each user's work is stored in a separate storage area

Performed by both the user and analyst. Searching the information space is done when the user knows what he is looking for, but does not know its location in the information space. This use case 'uses' three other use cases: 'Access search engine', 'View table of contents', and 'View index'

Performed by both the user and the analyst. Employs a keyword search or inferencing technique to search for a particular piece of information

Performed by both the user and analyst. Provides a list of contents in Hyper-Tmodeller

Performed by both the user and analyst. Provides an alphabetical listing of every keyword in Hyper-Tmodeller. Similar to an index in a text book.


5.2.1 Data Flow Diagram for Hyper-Tmodeller

A modelling session is defined here as a cycle commencing with the users posing their requirements and ending with the analyst producing a consolidated version of the tailorable model. User requirements are used to create an initial tailorable model that is then made accessible to the users involved in the modelling session. Each user makes modifications to the tailorable model where necessary. Each user's version of the model is then taken by the analyst and collectively is used to produce a consolidated version of the tailorable model. The user accesses the consolidated version of the model to work on and the cycle is repeated until a final version is agreed upon. Note that a modelling session does not require all participants in the modelling process to be working on the model at the same time. The idea is to enable all users to work on the model at their own time. Hence the duration of a modelling session can vary. The analyst may decide to take all users' work to produce the consolidated version of the tailorable model when he feels that there is enough information to work on. Alternatively, the analyst could set deadlines when all users' work will be taken to produce a consolidated version of the tailorable model. Figure 9 depicts a modelling session in Hyper-Tmodeller.

Table 3 provides a description of a dataflow diagram for a modelling session in Hyper-Tmodeller.

5.3 Class and Object Diagram

A class diagram depicts classes, their structures and the relationships between them, and an object diagram shows the relationships between various object instances. This subsection describes the class diagram and object diagram used and their notations, followed by an explanation of both diagrams for Hyper-Tmode!ler.

Users pose A final model is requirements agreed upon

T Analyst uses the

requirements to produce Analyst takes all f users' work to an initial tailorable model produce a consolidated version

~ of the tailorable model

Users make the / necessary

modifications to the tailorable model

Fig. 9. A modelling session in Hyper-Tmodeller.

338

Table 4. Description of the data flow diagram for Hyper-Tmodeller,

N.V. Patel

(!)

|

|

@

@

|

r

@

|

@

@

The modelling session begins with the users posing the requirements for the proposed system being modelled. Requirements can be entered into Hyper-Tmodeller and stored in the local storage area

The analyst extracts the user requirements from each user's local storage area. They are used to produce an initial tailorable model for the users to work on

The initial tailorable model created by the analyst is stored in the global storage area that is accessible to all users of the Hyper-Tmodeller

The initial tailorable model is extracted from the global storage area and modifications are made to it where necessary

Each user' s version of the modified model is stored in their respective local storage area

Each user's modified model is extracted from the their local storage area. The modified models are used to produce a consolidated version of the tailorable model

The consolidated version of the tailorable model is then stored in the global storage area for users to retrieve and work on

The consolidated version of the tailorable model is extracted from the global storage by the users and is modified. Modifying the consolidated model is similar to modifying the initial model. This process is repeated until a final model is obtained

The user searches Hyper-Tmodeller's database when he wants to find a particular piece of information

The specific piece of information is requested from the global and local storage areas. A search is performed on both these storage areas

The search result is returned to the user. The search result will indicate either a successful search (which would retrieve the information searched for) or an unsuccessful search

5.3.1 Class Diagram for Hyper-Tmodeller

T h e c lass d i a g r a m is b a s e d o n the o b j e c t m o d e l l i n g t e c h n i q u e ( R u m b a u g h et al.,

1 9 9 1 ) . T h e c l a s s d e v e l o p e d d e p i c t s t h e c l a s s e s in H y p e r - T m o d e l l e r a n d t h e

r e l a t i o n s h i p s b e t w e e n t h o s e c l a s ses . T h e r e l a t i o n s h i p s are s i m i l a r to t h o s e d e p i c t e d

in the o b j e c t d i a g r a m . T h e s e r e l a t i o n s h i p s s h o w n are b e t w e e n the c l a s s e s as o p p o s e d

to the ob jec t s . T h e f ive ob j ec t s in the c l a s s d i a g r a m are:

1. H Y P E R S E T ;

2. H T M _ C O M P O S I T E N O D E ;

3. H T M N O D E ;

4. H T M _ L I N K ; a n d

5. H T M _ O B J E C T .

E a c h o b j e c t ha s an a u t h o r a n d c r e a t i o n date . H T M L I N K S h a v e a s o u r c e and a

d e s t i n a t i o n . T h e s o u r c e is the o b j e c t the l i nk is r e f e r e n c e d f r o m a n d the d e s t i n a t i o n

is the o b j e c t the l i nk l eads to.

O p e r a t i o n s for all c l a s s e s i nc lude :

1. a ' C r e a t e ' o p e r a t i o n - u s e d to c r e a t e the ob j ec t s in the c lass ;

2. a ' M o d i f y ' o p e r a t i o n - u s e d to m o d i f y the o b j e c t s in the c lass ;

3. a ' D e l e t e ' o p e r a t i o n - u s e d to d e l e t e o b j e c t s in the c lass .


The HYPERSET is an aggregation of HTM_NODE and HTM_COMPOSITE_NODE objects. This is depicted by the 'part-of' relationships extending from the HTM_NODE class and HTM_COMPOSITE_NODE class to the HYPERSET class. HTM_COMPOSITE_NODE objects are an aggregation of various HTM NODE objects - depicted by the 'part-of' relationship extending from the HTM_NODE class to the HTM_COMPOSITE_NODE class. HTM_NODE objects are a collection of a number of HTM OBJECTs. Finally, an HTM_LINK links two objects in Hyper-Tmodeller together. HTM_LINK objects are associated with HTM_NODE, HTM_COMPOSITE_NODE and HTM_OBJECTs. An HTM_OBJECT is a piece of information in Hyper-Tmodeller. The relationships between these objects are discussed in more detail in the object diagram section for Hyper-Tmodeller below.

5.3.2 Object Diagram for Hyper-Tmodeller

The Object diagram depicts the aggregation hierarchy of the objects in Hyper- Tmodeller. The five objects are similar to the five shown in the classes above. The object diagram shows object instances from their respective classes. For example, HTM_Node(1), HTM_Node(2) and HTM_Node(3) in the object diagram are object instances of the HTM_NODE class in the class diagram.

The HYPERSET object is located at the top of the class hierarchy. The HYPERSET is an aggregation of a number of HTM_Node and HTM Composite Node objects.

This is denoted by the 'part-of' relationship (labelled @ and @) extending from the HTM_Composite Node and HTM_Node(1) to the HYPERSET object.

The HTM Composite_Node is a collection of HTM Node objects. This is denoted

in the class diagram by the 'part-of' relationship (labelled @ and @) extending from the HTM_Node objects to the HTM_Composite Node object. The HTM_Composite_Node may contain any number of HTM Node objects.

HTM Nodes are objects in Hyper-Tmodeller that hold a set of one or more interrelated information pieces (Wuwongse and Singkorapoom, 1991). It is a collection of a number of HTM_Objects. This is denoted in the class diagram by the 'part-of'

relationship (labelled @, @ and @) extending from the HTM Objects to the HTM_Node objects.

An HTM_Object is simply a piece of information in Hyper-Tmodeller. The HTM_Object can be in the form of either text, video, audio or graphics. An HTM_Object can also be aggregated into more than one HTM Node objects. This is

denoted by the 'part-of' relationship (labelled (~) and @) extending from the HTM_Object to two different HTM Node objects.

An HTM_Link object connects two existing objects in Hyper-Tmodeller. The HTM_Link object links two objects together by associating them via the HTM Link. Links may be created:

1. between two HTM_Node objects (denoted by the association relationship labelled

@ and @);

2. between an HTM_Node and an HTM_Object located in another HTM Node

(denoted by the association relationship labelled ~) and @); or

340 N.V. Patel

3. between an HTM_Node and an HTM_Object within the same HTM_Node (denoted

by the association relationship labelled @ and (~)).

6. Discussion

It is necessary to discover IS modelling techniques that cater for the dynamic nature of business activity. As IS development happens in the real world, dynamic modelling techniques are generally better suited than static ones. Hyper-Tmodeller is flexible and provides a dynamic way of modelling complex organisational business processes that are subject to change. System requirements gathering is thus better facilitated by a technique that captures the dynamism present in the real world.

In terms of systems development, the ability of analysts and designers has been hampered by their need to gather requirements and gain a clear understanding of the processes of the organisation. Hyper-Tmodeller provides a diagramming language that would be common to professional systems developers and business users. From the Hyper-Tmodeller specifications here and the significant design proposals it is clear that an interactive documentation method is indeed feasible - one that enables interaction among users, analysts and designers. The general communication gap among stakeholders can be reduced using CASE tools that are dynamic, to capture change in requirements, and intuitive, to enable non-professional users to actively participate in systems development.

The use of Hyper-Tmodeller ill the systems development process would not require users to learn complex modelling techniques like entity relationship diagrams. As Mouakket et al. (1994) show, both analysts and users find it difficult to learn and use entity relationship techniques in systems development. Using Hyper-Tmodeller users would be able to actively take part in the system development process.

In more general terms, the Hyper-Tmodeller CASE tool is a contribution to enabling deferred system design. It captures organisational context, work situations and users' interpretations of information needs. More importantly, it would enable users to take an active role in system design and development. Thus the work on Hyper- Tmodeller allows us to move in the direction of enabling users to be system designers.

7. Conclusions and Future Work

Informat ion-handl ing issues relevant to Hyper -Tmodel le r have been discussed and an explorat ion of a design specif icat ion for Hyper -Tmodel le r has been proposed. The four informat ion-handl ing issues addressed in the study include i n f o r m a t i o n o rgan i s a t i on , i n f o r m a t i o n s to rage , i n f o r m a t i o n access and information retrieval.

The global and local storage area addressed the problem of needing to provide users with a separate work environment and storage area to store their work and a separate storage area that holds the consolidated version of the tailorable model. The hypermedia engine enables the storage of information in a manner that is independent of the applications that will be used by users to manipulate the models in the system. An object-oriented database was deemed to be the best database to


store information in Hyper-Tmodel ler because of its ability to support the storage of various forms of information and represent real-world objects.

Navigational maps are useful in helping users browse the network of information in Hyper-Tmodeller . Abstraction was also discussed as a possible solution of too much information for maps to display. Help facilities help users use the system and must be implemented in Hyper-Tmodeller. Online guidance provides users with suggested topic areas based on the users' browsing patterns. These facilities helped address the ' lost in hyperspace ' problem inherent in hypermedia systems.

The design specifications produced are high-level designs used to help the reader understand how Hyper-Tmodeller works. The design specification addresses only the information-handling issues discussed in this paper. The Jacobson use case diagram and the Gane and Sarson data flow diagram modelled all information-handling issues. Rumbaugh ' s class and object diagrams modelled the object-oriented method for storage issue. These design specifications are the initial specifications and it is expected that modifications will be made during the course of Hyper-Tmodel ler ' s development.

Further research in Hyper-Tmodel ler in the area of human-compute r interaction is required. Other information-handling issues such as information display in user interfaces needs to be investigated. Human-compute r interaction is an important issue in every software system. It is important to consider how Hyper-Tmodeller will interact with its users. Bickford (1997) provides guidelines for designing user- friendly interfaces relevant to Hyper-Tmodeller , which may be further explored. The user interface for Hyper-Tmodeller requires considerable attention because it will be used by a number of different users.

Other methods of storing information such as frames and relational databases could also be investigated to determine if they can provide other features not provided by object-oriented databases. Frames are common methods of information storage in knowledge-based systems (Gonzalez and Dankel, 1993) and relational databases have been the most popular form of information storage in commercial software.

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Correspondence and offprint requests to: Nandish V. Patel, Department of Information Systems and Computing, Brunel University, Uxbridge UB8 3PH, UK. Email: [email protected]