Techniques In Information Systems Development Methodology

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

A Classification of Techniques StageOverallDataProcesses StrategyRich pictures AnalysisRich pictures,Objects, Matrices, Structure diagrams Entity Modeling DFD, Entity life cycle, Process logic, Root definitions, Conceptual models Logical Design Objects, Matrices, Structure Diagrams NormalizationProcess logic Program/ Database Design Objects, Matrices, Structure Diagrams NormalizationProcess logic

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.

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”

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

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

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

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

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

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

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

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’

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

Start state Same state End state Entity state Event Process

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

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

A BC D E F G 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

Matrices Function Event Process enquiry SelectionEnrol ment Accoun ts Student Enquiry XX Student Accepted XX Student registers X