Systems Analysis Course

• Home
• 1.What is a System
  • Introduction
  • Parts of a System
• 2.System Lifecycle
  • Project Management
  • Project Lifecycle
  • Check Understanding
  • SDLC Comparison
  • Exercise
• 3.Feasibility Study
  • Sections
  • Exercise
• 4.CostBenefit Analysis
• 5.System Investigation
  • Introduction
  • Methods
  • Identify method
  • Exercise
• 6.Data Flow Diagrams
  • Introduction
  • Video
  • Definitions
  • Steps to create
  • Exercises
• 7.Relational Diagrams
  • Terminology
  • Examples
  • Exercise
  • Using a DFD level1
• 8.Data Dictionary
• 9.Design Specification
• 10.Creating a Test Plan

 

 

Lesson 2 - System Development Lifecycle

Project Lifecycles

Projects are divided into phases to identify smaller chunks that are more manageable in terms of time, cost and specification. These phases do the following:

• Provide checkpoints and review points
• To encourage rolling wave planning
• Improve accuracy of estimating
• Focus on the right work at the right time in the right order

 

A typical project lifecycle to develop a computer system might comprise of the following phases

Initial Project Planning	The idea of the project is first conceived
Feasibility	The purpose of this phase is to decide if the project is a good idea and whether it will go ahead
Analysis	At this phase the System is modelled and the user requirements analysed to come up with a solution for the problem.
Design	This is when the System is designed. This includes screen designs, graphics, programs etc
Development	At this phase the System is actually created and computer programs are written
Testing	This is when the System is tested to make sure that everything performs correctly
Implementation	Here the System goes live and starts to be used by the business
Maintenance	This phase represents the day to day running of the system for the business. If any bugs are found they will be corrected as they are detected.
Disposal/Termination	This is when the system becomes obsolete, is no longer required by the business and is removed.

Note that this is a "Typical" lifecycle many organisations will use different phases depending on their specialisation.

 

Several models exist for the Systems Development Lifecyle.

The waterfall model

 

Perhaps the original in which the project is split into phases each of which must be completed and signed off before the next is started. Changes required in one phase must be assessed for impact on earlier phases.

The V model,

often used for the software project, is an extension of the waterfall model. With this model each development phase has an associated verification and validation phase, the test plans are the links between these activities.

Other models are in use which use a prototyping approach to system development, or RAD (Rapid Application Development) methodologies such as DSDM (Dynamic System Development Methodology).

Many of these use an iterative or spiral lifecycle model. In these cases the iterations to be performed are determined during the early stages of the project execution.

The Spiral Lifecycle Model

System Development Life Cycle

The Systems Development Life Cycle used to develop computer systems has evolved from the structure set out in SSADM.

SSADM stands for Structured Systems Analysis and Design Method

The life cycle is a continuous loop. At the end of the project development, implementation and review should take place. This might include:

• Further upgrading and development
• Adjustment to the project
• Closure and signing off the project

The review therefore feeds back into the initial project planning stage. If further adjustments or upgrades are required, this will instigate another feasibility study and the launch of further projects.

 

 

 

Copyright JK Nichols 2009