A system is an orderly grouping of interdependent components linked together according to a plan to achieve a specific objective. The study of system concepts has three basic implications:
- A system must be designed to achieve a predetermined objective.
- Interrelationships and interdependence must exist among the components.
- The objectives of the organization as a whole have a higher priority than the objectives of its subsystems.
Characteristics of a system:
It implies structure and order. It is the arrangement of components that helps to achieve objectives.
It refers to the manner in which each component functions with other components of the system.
It means that parts of the organization or computer system depend on one another. They are coordinated and linked together according to a plan. One subsystem depends on the output of another subsystem for proper functioning.
Integration: It refers to the holism of systems. It is concerned with how a system is tied together.
A system should have a central objective. Objectives may be real or stated. Although a stated objective may be the real objective, it is not uncommon for an organization to state one objective and operate to achieve another. The important point is that users must know the central objective of a computer application early in the analysis for a successful design and conversion.
Difference Between structured systems and object oriented systems:
Object Oriented: Iterative/Incremental
Object Oriented: Object
Object Oriented: Low
Object Oriented: High
Structured: Mature and Widespread
Object Oriented: Emeraging
Structured: Well-defind projects with stable user requirement
Object Oriented: risky large projects with changing user requirement
Structured: Structuring Requirements: - DFD's - Structure English - Decision Table/Tree - ER Analysis Object Oriented: Requirement Engineering 1. Use Case Model - Use Case Diagram - Flow Diagram - Activity Diagram 2.Object Model - Find Classes and Class Relationship
- State Diagram, Sequence Diagram - Collaboration Diagram
Structured: DB design (DB normalization) GUI Design (forms & reports)
Object Oriented: Physical DB design
- Design system Architecture
- Design classes: Checking The Model, Combine Classes,
Splitting Classes, Eliminate Classes
- Design components
- GUI design