National Diploma Unit 4 Introduction to Software Development Program specification & development

Starting points The user’s requirements should form the basis for the specification In analysing them, you need to consider constraints in any form e.g. budget, hardware available From all of your considerations, you need to produce a formal specification for the program

Specification This should describe what inputs are required The processing needed The output format The hardware specification The software required e.g. specific OS or applications

Modular design It is current practice to modularise programs Advantages Each component can be worked on concurrently by team members Each part can be tested on its own Pieces can be reused if they are fairly general

Rapid Application Development VB is a RAD programming environment – but what does this mean? VB is a programming environment that allows you to produce an interface for the user to see immediately You can then ask for feedback straight away You can refine your ideas “on the fly” The user is generally involved at all stages

Rapid Application Development You may end up producing loads of intermediate products none of which actually get used Users sometimes want something that you cannot produce You get down to the designing straight away without the careful planning and documentation used in more formal software development models

Specification practice “ I need a program to calculate the amount of sick pay payable to my employees. If they are off sick for four weeks, they get full pay. After that time they get 75% until they have been ill for 6 months. After that time, they get 50% pay. The program should calculate the total sick pay for the member of staff and allow it to be stored on the hard disk drive

Specification practice “ I run Windows 98 on my peer to peer network and all of the computers have Microsoft Office 97 installed. I don’t want the program to be too complicated – even my junior clerks must be able to use it. It must not be too big either – none of our machines have more than 500Mb free on their hard discs.

Specification practice “We use a mouse and keyboard only for input and have VDUs and laser printers in the office. I don’t want to have to buy any expensive equipment or to upgrade any of my machines in order to run this program. “I want it to be reliable as I will need it 52 weeks of the year and it will be used by many staff. I don’t want a program that will crash or wreck my computers”

Task Work in a pair and produce a specification for this program