Systems Analysis & Design: Topic 9

Entering the Design Phase

Systems design -- the process of determining the components and the interconnection among those components in the best possible way in order to solve a problem (i.e., the problem that was explained in the requirements specification.)

Phase Name: DESIGN
Major Function:To design a new system that fulfills the requirements of the users and management.
InputThe objectives, functions, and boundaries as determined in systems analysis.
OutputThe design specification.
Principal Toolsdata dictionary
data flow diagrams
process specifications
prototyping
structure charts
input and output design forms
CASE tools
Personnel and Tasks:  
Analyst:
  • evaluates and orders all necessary hardware and software.
  • transforms the functional diagrams of the analysis phase into the hierarchical diagrams of the design phase.
  • designs the user interface, including input and output formats.
  • incorporates system security measures into the design.
  • determines staffing requirements and design procedures workflow.
Database designer:
  • designs the required database.
Users, managers, and team members:
  • review the design specifications for accuracy and completeness.


APPROACHES TO SYSTEMS DESIGN

Systems have two major parts which designers must cope with: functions and data.

Functions manipulate data in order to produce the desired results.

Process-oriented Design Approach

Data-oriented Design Approach


HIERARCHICAL DIAGRAMS

USER INTERFACE DESIGN

FAULT TOLERANCE AND SECURITY

DATABASE DESIGN AND OTHER ACTIVITIES

THE DESIGN SPECIFICATION

Contents of the Design Specification