SSAD, OOPS

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Structured System Analysis and Design (SSAD)

Every software application development has to go through number of stages called Project Life Cycle.  There are many methods and in general they are,

User Requirement Analysis, Design
Application Development
Testing
Unit Testing
White box Testing
Black box Testing
User Acceptance Testing
Implementation
Evaluate and Enhance

User Requirement

First we study the user requirement clearly and document (Functional Specification document) that.  After many discussion, once our doubts are thrashed out completely we document the requirement and get it approved by the user. 

Use Data-Flow-Diagram (DFD), Flow-chart to depict the requirement in the document.   DFD is particularly useful in figuring out the important processes and how the data will be stored.  From DFD we can identify the number of screens for input, query and report generation.  We can also identify the tables, its columns and their relationships with other member tables.

A technical design document will contain how the application is going to be developed and its methodologies.  It briefly explains the tools to be used for the purpose.   It normally contains:

Entity-Relation (ER) Diagram
Pseudo-codes, English-like code structure
Flow Charts
Any calculations
Screen designs and its description
Screen logic - business logic
Input Fields description, validation rules
How the screen is accessed - from menu, button etc.
Report designs and its description

Development

As an application grows larger and larger it becomes difficult to maintain.  So from the beginning an application is demodularized (functional decomposition) into small modules.  Modular programming approach helps the programmer to develop, debug, maintain his/her code more easily and efficiently.

Debug:  Finding and fixing errors in a set of codes.

Object Oriented Analysis and Design (OOAD)

After the dawn of Object Oriented Programming Languages such as SmallTalk, C++ a new system evolved to develop an application, called Object Oriented Programming Systems (OOPS).

It requires a radical change in approach followed by programmer, who used SSAD for their application development.  SSAD is following top-down approach and data has no protection, in other words, data is independent of the programming.  Data does not know by itself what it can do.

OOPS changed all that and data become much important.  Read Understanding OOPS section of this site to learn more about OOPS.

 

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Last modified: January 21, 2000