Techniques In Information Systems Development Methodology

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Techniques In Information Systems Development
Methodology
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Kinds of Techniques

• Rich Pictures
• Root Definitions
• Conceptual Models
• Entity Modeling
• Normalization
• Data Flow Diagram
• Decision Trees
• Decision Tables

• Structured English
• Action Diagrams
• Entity Life Cycle
• Object Orientation
• Structure Diagrams
• Matrices

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A Classification of Techniques
Stage Overall Data Processes
Strategy Rich pictures
Analysis Rich pictures,Objects, Matrices, Structure diagrams Entity Modeling DFD, Entity life cycle, Process logic, Root definitions, Conceptual models
Logical Design Objects, Matrices, Structure Diagrams Normalization Process logic
Program/Database Design Objects, Matrices, Structure Diagrams Normalization Process logic
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Rich Pictures

• Help to understand the problem situation in
  general at beginning of a project
• It is a pictorial caricature of an organization
• It is a tool for helping to explain what the
  organization is about
• It helps people to visualize and discuss their
  roles
• It can show the worries of individuals, potential
  conflict, and political issues
• Etc.

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Root Definitions

• Can be used to define two things that are
  otherwise both vague and difficult problems and
  systems
• A concise verbal description of the system which
  captures its essential nature
• Who is doing what for whom, and to whom are they
  answerable, what assumptions are being made, and
  in what environment is this happening?
• C(lient) A(ctor) T(ransformation) W(eltanschuung)
  O(wner) E(nvironment) CATWOE
• A system owned and operated by the professional
  association to administer the examinations by
  registering , supervising, recording and
  notifying students

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Conceptual Models

• It is an essential element in the architects
  design activities
• It is a medium of communication between
  architects and clients to enable the right design
  to be selected
• It is a set of instructions to the builders

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Entity Modeling

• Define the area for analysis
• Define the entities and the relationships between
  them
• Establishing the key attributes for each entity
• Complete each entity with all the attributes
• Normalize all the entities
• Ensure all events and operations are supported by
  the model

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Normalization

• It is a process of transforming data into well
  formed or natural groupings such that one fact is
  in one place and that the correct relationships
  between facts exist

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Data Flow Diagram

• Provides the key means of achieving one of
  structured systems
• Provides the analyst with the ability to specify
  a system at the logical level
• Represents logical information, not the physical
  aspects

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Decision Trees

• To facilitate the documentation of process logic,
  particularly where there are many decision
  alternatives
• Decision trees are constructed by first
  identifying the conditions, actions

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Decision Tables

• Appropriate where there is a large number of
  actions as they can be decomposed into sets
  conveniently

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Structured English

• It is a precise way of specifying a process, an
  is readily understandable by a trained systems
  designer as well as being readily converted to a
  computer program
• Sequencing
• Selection
• Repetition
• Case

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Action Diagrams

• Support the structured programming constructs of
  condition, case, repetition, reapeat.until

Admit a student Review application Interview
student Make decision Communicate decision
Function admit a student
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Entity Life Cycle

• It is used at a variety of stages in a number of
  methodologies and is one of the few attempts to
  address changes that happen over time
• The diagram provides a pictorial way of
  communication that enables users to validate the
  accuracy or otherwise of the analysis

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End state
Start state
Event
Same state
Entity state
Process
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Object Orientation

• An object is something to which actions are
  directed, it has an identity, a state, and
  exhibits behavior

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Structure Diagrams

• Representing processes or parts of computer
  programs (modules) and connecting lines
• Each module should be small and manageable

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A
D
G
F
E
B
C
Module A can call module B and also module C When
A calls B, it sends data of type D to B, when B
terminates, it returns data of type E to A. Its
variation Warnier-Orr diagram
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Matrices
Function Event Process enquiry Selection Enrolment Accounts
Student Enquiry X X
Student Accepted X X
Student registers X