Full text: Systems for data processing, anaylsis and representation

un Systeme 
ormation soit 
> le Système 
Méthodes de 
:'veloppement 
veloppement 
la procédure 
  
Benefits from Methodologies should include high quality 
products which are easy to maintain and upgrade, better 
control during the design process, reduction time to 
completion and lower costs of developments. 
Unstructured Methodologies 
Generally referred to as "Conventional Approach" in most 
texts, they where prevalent in the 1970s. The philosophy 
behind these Methodologies is visualised as shown in 
Figure 1. 
^N 
TOP ( STRATEGIC ) 
MANAGEMENT 
IGNORED BY 
COMPUTER 
MIDDLE ( TACTICAL ) 
MANAGEMENT 
  
  
OPERATIONS 
MANAGEMENT 
  
  
(a). Failure to meet all Organisational needs. 
  
WHAT FILES WILL 
HOLD THE NECESS- 
ARY STATIC DATA? 
des 
WHAT DATA WILL 
  
  
  
  
  
  
  
WHAT ARE THE WHAT PROCESSES 
A] WILL LEAD TO 
REQUIRED 
v] THAT OUTPUT 
OUTPUTS ? BEING ARCHIEVED? 
  
  
  
  
  
  
  
  
BE REQUIRED AS 
RAW INPUT? 
(b). Output Driven Design. 
Figure 1 A Window on Unstructured Methodologies 
(Adapted from Avison & Fitzgerald) 
m Unstructured Methodologies were unsatisfactory due 
0: 
Failure to meet the needs of management, instability and 
Inflexibility, user dissatisfaction, problem of documentation, 
incomplete Systems, little or no control over the quality of 
the design, and lack of an objective criteria with which to 
judge whether the critical activities of analysis and design 
were carried out properly [Yourdon, 1988]. 
These create concern for: 
Low productivity, low quality, long development cycles, 
increasing costs of development and maintenance of 
Systems, and thus create the need for Structured 
Methodologies [Paresi, 1991]. 
The concern for more productive methods for the 
development of information systems has therefore 
tremendously increased during the last two decades. A 
wealth of research has addressed the problem of 
developing efficient and effective Information Systems. Four 
approaches to development methodologies have emerged 
from research and experience; these are the formal 
methods, the structured methods, the soft methods, and 
the socio-technical methods. In practice, any development 
is a combination of these different approaches; only 
Structured Development Methodologies will be considered 
here. 
Structured Systems Development Methodologies 
Necessity and Basic Features: 
Given the generic objectives of Methodologies as stated 
earlier, it is obvious that conventional approaches fail 
particularly when Systems become more complex. 
Structured Methodologies seek to address these failures as 
outlined above with particular consideration to the reduction 
of the cost of rectifying changes in user requirements. Such 
changes would remain minimal if these requirements are 
considered extensively during the analysis phase [Cutts, 
1991]. They also seek to mirror organisational patterns 
faithfully during implementation [Ward,1984]. Some of the 
fundamental features of Structured Methodologies include: 
(1) A Top-Down approach with a strict philosophy of 
separating the conceptual System from the physical 
System. Much effort is put developing the conceptual 
system during which the analyst gets an overall grasp 
of the System, breaks the picture down in manageable 
details, with a productive use of time. 
(2) They avoid the duplication of efforts and waste of 
resources, thereby reducing the volume of work and 
speed up the overall System Development process. 
(3) Much of the documentation, which is in the form of 
diagrams and systems encyclopedia (or data 
dictionary), are better understood by non-technical 
users, and clear thinking is encouraged. 
(4) By encouraging standardized methods, another 
designer can easily assimilate the steps, and 
System maintenance becomes less cumbersome. 
(5) The Techniques and Tools are not ‘doctrinal’ or 
inflexible and force the analyst to ask questions to 
users, and of himself, thereby minimising wrong 
assumptions during design. 
(6) Most parts of the analysis and design can be 
developed, maintained and held on computer 
systems (CASE tools), easing the work of 
documentation. 
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