Systems Development Methodologies

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Systems Development Methodologies
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• The Nature of a Method
• Methods (or Methodologies) are systematic
  approaches to solving a problem.

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• A common approach to problem solving
• Divide problem into sub-problems until they are
  sufficiently small to be understood.
• Solve the sub-problems.
• Synthesise the sub-problems into a complete
  solution.

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Common Model for solving difficult problems.
But How do you break the problem down? How do
you do the sythesis?
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• Systems development problems can be broken down
  to smaller problems using
• Systems Theory
• Lifecycles
• Information Systems Architecture

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• Systems Theory (1) Process Oriented
• A system has inputs from its environment and it
  outputs to its environment.

A business system is composed of people,
material, facilities, equipment and methods to
supply goods or services.
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• Systems Theory (2) Object Oriented
• Systems are collections of objects with their own
  properties. These objects interact with one
  another.

Business objects are those things which assist a
business to reach its goals. Eg. A person, some
thing, a transaction that performs a function.
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• Systems Theory (3) Paradigms
• A paradigm may be defined as a way of thinking or
  mindset to understand reality.
• In Economics (Keynesians/ Market Rationalists)
• In Psychology (Freudians and Jungians) etc
• For Systems Analysis there are three main
  paradigms
• Structured Analysis Process oriented
• Information Engineering Data and business
  alignment oriented
• Object Oriented Analysis User view, class
  oriented

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• Paradigm shifts in Systems Analysis
• in the 1970s from Ad Hoc to Structured Analysis
• in the 1980s from Structured Analysis to
  Information Engineering
• in the 1990s from Information Engineering to
  Object Oriented.

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• Information Systems Architecture

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• Lifecycles

A System Life Cycle divides the life of an
information system into two, systems development
and systems operation and support.
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An example of a system development life
cycle Planning Analysis Design Build I
mplement Operate Here the phases provide
the input to the next phase and feedback to one
another. There are many other SDLCs.
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• The need for
• Systems that meet the users needs, are within
  budget, and are on time
• Require
• an organised, consistent method for the solution
  of systems problems.
• Methods (Methodologies) are derived from
• Systems lifecycles, Systems theory, Analysis by
  abstraction

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• Methods provide
• A set of steps to follow assist project
  management
• A set of techniques to use to model the system
• A set of deliverable to define and document each
  step of the analysis
• A set of standards to follow.

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