ENM407 System Analysis

Introduction to system analysis

Asst. Prof. Dr. Gülçin Dinç Yalçın

What is a system?

What is a system?

❖ A system is a set of interacting or interdependent components forming an integrated whole.

❖ A system has a structure, it contains parts (or components) that are directly or indirectly related to each other.

❖ A system is anything with a purpose.

❖ A system must do something.

What is a system? (cont.)❖ A system is a set of two or more elements that satisfies the

following conditions:

❖ The behavior of each element has an effect on the behavior of the whole.

❖ The behavior of the elements and their effect on the whole are interdependent.

❖ However subgroups of elements are formed, each has an effect on the behavior of the whole and none has an independent effect on it.

What is a system? (cont.)

❖ The human body: made up of many smaller systems

❖ Education system: university, departments, classes, student

❖ Stellar system: galaxies, solar system

❖ Geological systems: rivers, mountain ranges

❖ Molecular systems: complex organizations of atoms

What is a system? (cont.)

❖ Manufacturing systems: factories, assembly lines

❖ Social systems: organizations of laws, doctrines, customs

❖ communication system: telephone, computer

What is a system? (cont.)

❖ However, a cluster consisting of all elements is not a system.

❖ Random standing items on the table

❖ Are they purposive?

❖ Is there a functional relationship?

Nine Characteristics of a System

Nine Characteristics of a System❖ Component: An

irreducible part or aggregation of parts that makes up a system; also called a subsystem

❖ Interrelated:Dependence of one part of the system on one or more other system part

Nine Characteristics of a System (cont.)

❖ Boundary: The line that marks the inside and outside of a system and that sets off the system from its environment.

❖ Purpose: The overall goal or function of a system.

Nine Characteristics of a System (cont.)

❖ Environment: Everything external to a system that interacts with the system.

❖ Interface: Point of contact where a system meets its environment or where subsystems meet each other.

Nine Characteristics of a System (cont.)

❖ Constraints: A limit to what a system can accomplish.

❖ Input: Input involves capturing and assembling elements that enter the system to be processed. The inputs are said to be fed to the system in order to get the output.

Nine Characteristics of a System (cont.)

❖ Output: Those elements that exists in the system due to the processing of the inputs is known as output. The output of a system maybe in the form of cash, information, knowledge, reports, documents etc.

Components of a System

Components of a System

❖ Element

❖ Attribute

❖ Event

Components of a System (cont.)

System Element Attribute Event

TransportationVehicle

SignThe way

SpeedColourLenght

Transport

Information Systems

Information Systems

❖ There is a difference between data and information

Information Systems (cont.)

❖ There is a difference between data and information

❖ 42,12,45,13,19 and 34: Data (no meaning)

❖ Turn them something in useful: Information

What is system analysis?

What is system analysis? (cont.)

❖ Find out what is good and what is bad of the current system.

❖ Design a new system that keeps the good thing and gets rid of the bad things.

What is system analysis? (cont.)

❖ The user understands the current system but the analyst does not.

❖ The analysts understands the new system but the user does not.

❖ There is a gap.

❖ Effective communication is vital.

System Methodology

System methodology

❖ A methodology is a strategy for overcoming the problems faced by the system analysis.

❖ One type of methodology is called structured.

System methodology (cont.)

❖ If the analyst follows the steps of the methodology, then eventually quality information systems design should be the outcome.

❖ The analyst will break down complex systems into smaller, well-defined and well-documented chunks.

SSADM-Structured System Analysis and Design Method

SSADM-Structured System Analysis and Design Method

❖ Basic principles:

❖ 1) Break down complex system into chunks

SSADM-Structured System Analysis and Design Method

❖ 2) Analyze the current system

❖ Physical: How things are currently done, who does them.

❖ Logical: What is currently done.

❖ Design the new system

❖ Logical: What will be done.

❖ Physical: How things will be done, who will them.

SSADM-Structured System Analysis and Design Method

❖ 3) Users get involves from the start.

❖ 4) Make effective use of diagrams.

❖ 5) The analyst see the system from different views: cross-checking.

❖ 6) SSADM has been around for a good many years.

The structure of SSADM

The entire project is worth pursuing?

what problems that have, what they want from the new system

A range of options, with different costs

and benefits, are considered.

-This involves specifying the

required system.

-An overview of the underlying data structures for the required

system is created.

-what the new system will be expected to do.

-consider technical options.

-specifying the new system

-what will be the new system

do?

-what might it look like from a

user perspective?

-concentrates on the environment

within which the new system will be running.

-storage requirements

and performance

issues.

SSADM and the system development life cycle

system development life cycle