Please enable JavaScript.
Coggle requires JavaScript to display documents.
INFO 3 - C6 Development Methods (Testing (This is part of the creation to…
INFO 3 - C6 Development Methods
System Dev. Life Cycle
All systems need to have a method of how they are developed
Sometimes see standard circular cycle or in the 'waterfall method, thing included are:
Analysis
Design
Creation of system
Testing and documentation
Installation and Conversion
Review and Maintenance
Each section has to be complete before moving on - this means that all the sections are done and no problems go through
At the end of each stage there will be agreed deliverables, which can be signed off by a client
Stages of Dev.
Project Definition
This is setting the scene stage and is concerned with looking at the organisation from the strategic level: getting an overview
Gives reasons for the new system that is to be developed, reasons why a new system is needed
Feasibility
Addresses the following points:
The problems with the existing system
The objectives of the proposed system
An analysis of the different ways that the problem can be solved, together with the recommendation of the proposed solution
The feasibility study will include timescales for the development, and a proposed buget for dev and running of new system
Technical Feasibility - new system work?
Economic - save company money?
Legal - Break the law?
Operational - solve the problem?
Schedule - Produced benefits in time?
TELOS
Systems Analysis
This explains what the new system is going to do by breaking down the problem into smaller and smaller pieces. Systems analysis is very important as it sets the scene for the rest of the development
Understanding the system
This is to see exactly what it does
To show its strengths and weaknesses
Identifying the client's and the users' requirements for the new system
Formulating the requirements specification for the new system
Explanation of what is required of the new system
Any constraints that need to be placed on the new system
The Analyst uses a number of different techniques to find the information:
interviewing all users at all levels of the organisation, not just the client
Questionaires
Observation of the current system in operation
Analysis of existing documentation
Design
The design puts the breaking down of the problem back together again it has analysed each section
Documentation must be accurate, and anyone with the correct knowledge should be able to pick up the designs and produce the solution without any difficulty
Creation of a System
Customising a ready-made package
Creating a customised application from a generic piece of software
Programmed from scratch (bespoke)
Using programming and a generic package
= all equals a solution to a problem
Testing
This is part of the creation to the system
Unit testing
- involves testing each of the sections to make sure they do what they are supposed to do
Integration testing
- usually carried out at the creation stage and is the testing of combined units
Functional Testing
- tests the operation of the system and may pick up errors missed previously by the programmers
System / alpha
- carried out by the programmers
User Testing / beta
- testing that is carried out by the user
Operational testing
- testing carried out in a live environment in which the system will be used
Deliverables at the end of the testing process are:
test data and the results of testing
the improved user guide
the improved technical guide
Client approval to install
Installation and Conversion
Direct Changeover
- changing the system from the old in one operation
Parallel Running
- old system remains in operation as the new system is implemented
Pilot Changeover
- One branch or department tries out the new system
Phased Implementation
- Section are implement and phased into operation until whole system is operational
Review and Maintenance
- continuously reviewed and monitored after installation
Corrective Maintenance
- correcting any reported errors
Adaptive Maintenance
- altering the system to meet new requirements
Perfectible Maintenance
- improving to enhance performance
Iterative Methodologies
Iteration means repeating something over and over until you get the solution
Iterative methodologies have been developed to improve the waterfall model
Developers can go back and improve a previous stage using the results from a later stage
Iteration can lead to the constant redesign and implementation of the system
Can be time-consuming and this is important to set timescales so this is not allowed to happen
Comparison model - Waterfall and iterative
Linear
Allows the development of a new system in a linear order or sequence.
Stages of development have to be completed in a fixed order and the next stage cannot be completed until the previous stage has been completed
Waterfall Model phrases
Requirements Specification
Design
Construction
Integration
Testing and debugging
Installation
Maintenance
Named waterfall due to the tasks flowing from the top the bottom