1.2.3 Software Development

Describe the waterfall method

• includes analysis, design, implementation/programming, test, evaluation,

• each phase is moved down in linear process

• phases can be revisted back in turn

Advantages and disadv of the waterfall method?

advantages

• Model is simple to understand and use (1)

• Each stage is separate and self-contained with well-defined outcomes and written documentation (1)

• This makes the project relatively straightforward to manage (1)

disadvantages

• There is not much user involvement after the Analysis stage, when the Specification document is agreed (1)

• No working software is produced until late in the cycle (1)

• The user is presented with the finished product and if it is not quite what was required, it is generally too late to make changes (1)

describe the spiral method

• incremental design

• includes planning, design, programming and evaluation

• at the end of all 4 phases it repeats

• each phase usually adds a new element to the problem

• is used to manage risk

• prioritises riskiest elements first

advantages of the spiral model?

• Software is produced at an early stage so problems and issues can be identified early

• The user gives feedback on each prototype and any required changes can be made early in the process

• Added functionality can be added during the process

• The end result is more likely to be what the user wants

disadvantages of the spiral model?

• The process of developing prototypes, getting feedback and refining the prototypes is time-consuming so the finished product takes longer to develop

• A system is more costly to develop because of the time involved

explain RAD

• iterative approach to software development.

• emphasis is on developing prototypes rather than extensive 'requirements documentation' up-front.

• no formal analysis, design stages

• faster development

• more feedback used to influence future stages

advantages to RAD

• Caters to changing user requirements

• Highly usable finished product

• Focus on core features, reducing development time

disadvantages to rad

• Poorer quality documentation

• Fast pace may reduce code quality

define agile methodology

• It combines a sequential and iterative approach.

• the problem is broken down into sections which are developed in parallel

• adapt to changes in user requirements faster.

advantages of agile methodology

• Produces high quality code

• Flexible to changing requirements

• Regular user input

disadvantages of agile methodology

• Poor documentation

• Requires consistent interaction between user and programmer

define extreme programming

agile model in which the development team consists of a pair of programmers alongside a representative end-user.

advantages of extreme programming

• Produces high quality code

• Constant user involvement means high usability

disadvantages of extreme programming

• High cost of two people working on one project

• Teamwork is essential

• End-user may not be able to be present

define an algorithm

An n algorithm is a set of instructions used to solve a problem.

what functions are needed for an algorithm to be valid

• Must be able to deal with invalid inputs

• Must always reach a stopping condition

• Must be well-documented for reference

• Must be well-commented so modifications can easily be made

define alpha and beta testing

• Alpha testing is carried out in-house by the software development teams within the company.

• Beta testing is carried out by end-users after alpha testing has been completed. Feedback from users is used to inform the next stage of development.

Describe 3 features of an Object oriented language.

• programs split into object which are used to build a complex system

• uses encapsulation to hide data within objects

• inheritance is when a class inherits an attribute

• self contained object contains routines / methods / attributes / data

Describe two benefits of using an object oriented paradigm rather than a procedural paradigm

• code can be easily reused

• classes can be used in other programs

• easier to maintain

• as classes can be modified or extended

• debugging can be easier as encapsulation limits how attributes are changed