Supplement 02 (a)Systems Theory1 Supplement 02 (a) Systems Theory And Franchise Colleges By MANSHA NAWAZ

Supplement 02 (a)Systems Theory2 Learning Aims Objective 1 –to understand the concept of a system Aims –identify systems from everyday experience –identify component parts of systems –distinguish sub systems within larger systems –state boundaries of systems Objective 2 –to be able to draw up a Terms of Reference list for a proposed small scale computerised system Aims –state system purpose –identify system boundaries (terms of reference) –outline basic system functionality –list other non-functional constraints

Supplement 02 (a)Systems Theory3 A System - Definitions “A set of inter-related functions (tasks or procedures) which work toward a common goal” Nawaz 1984 “A system is a set of activities collaborating to perform some function independent to, but influenced by its environment” Wroe 2001 “A system is an integrated set of components with an identifiable boundary working together for some purpose.” set of components organised together to form a whole to achieve a purpose

Supplement 02 (a)Systems Theory4 Characteristics of a System Components Interrelationships Boundary Constraints Purpose Environment Interfaces Input Process Output examples –central heating system –digestive system –computer system

Supplement 02 (a)Systems Theory5 Characteristics of a System

Supplement 02 (a)Systems Theory6 An Example System

Supplement 02 (a)Systems Theory7 Boundaries what is inside –component parts what is outside –the environment exchanges across possible –inputs –outputs

Supplement 02 (a)Systems Theory8 Components (Sub-systems) a system can often be divided into a number of smaller systems hierarchical structure –work down and up purpose of lower system rooted within the higher

Supplement 02 (a)Systems Theory9 SAD & Computer Systems Systems Analysis and Design in this module is restricted to... –the activities carried out in the elicitation of requirements and the specification of computerised systems Computerised Systems consist of... –hardware –software –data –operational procedures –people

Supplement 02 (a)Systems Theory10 Systems Input – Process - Output Boundary INPUT OUTPUT SYSTEM Environment

Supplement 02 (a)Systems Theory11 Sub-systems Input – Process - Output Boundary SYSTEMS are comprised of Environment INPUT OUTPUT Z Y A B Sub Systems CONTROL

Supplement 02 (a)Systems Theory12 Decomposition or Modularity – the breakdown of a system into sub-systems Coupling & Cohesion –The interaction between decomposed modules (lower level module interaction) Systems Decomposition & Modularity

Supplement 02 (a)Systems Theory13 Systems Analysis : –Breaking down a system into APPROPRIATE manageable parts Results in Decomposition or Modularity –useful components (sub-systems) of a system –In systems development often called MODULES … connected to other modules –COUPLING is the extent to which modules are dependent on each other

Supplement 02 (a)Systems Theory14 Why is Systems Analysis Important? Helps us analyse complex things –Breaking them down into manageable parts BUT remember –The analysis is often a SUBJECTIVE view The Systems Analyst –Skills to analyse systems –Links Business process and IT knowledge

Supplement 02 (a)Systems Theory15 Why is General Systems Theory Important? Considers the System as a “whole” –holistic view Interaction among the subsystems is of great importance –Helps build an image (picture) of the system –complex interactions not seen until decomposition

Supplement 02 (a)Systems Theory16 Systems Summary Purpose Components (sub-systems) Interrelationships Boundary Purpose Environment Interfaces Input – Process - Output