1.2.3 Software Development

the distinct phases which programmers go through when developing a solution for a computer system

the arrangement and how programmers move from one phase to another in the software development lifecycle

• feasibility • requirements • analysis and design • implementation • testing • deployment • evaluation • maintenance

waterfall rapid application development sprial agile extreme programming

• each phase has a well defined start and end point with identifiable deliverables • once you end one phase, you never really return to it and move onto the next one

• produces successive prototypes of the software until the final version is produced and approved • following approval of the feasibility of the program, increasingly refined prototypes are made wit reduced functionality • each prototype is designed, coded, tested and evaluated with the user

• determine objectives • identify and resolve risks • development and test • plan for next iteration

• risk driven • provides a guide for the team where the decisions on the software development methodology are made based on the risks identified

a group of methodologies which focus on the idea that requirements will shift and change during development and this can only be dealt with in an iterative way.

short, time boxed periods when a team has focused goals to complete a set amount of work - should only be a bite sized piece of focused work

a framework for software development

produce high quality code and promote developers’ quality of life by adopting a set of common practices

• simplicity • communication • feedback • courage • respect

• collective code ownership • continuous integration • code standards • refactoring • paired programming

• simplicity = easy to manage • everyone knows responsibilities at each stage • clear deliverables • easy to see if project running to schedule

• carries a lot of risk • user doesn’t get to see product for the first time until the end is near • misunderstanding requirements can lead to the problems not easy to fix • requirements must be well understood so not suitable for complex projects

ease of management means it is suitable for large scale development projects - have to be well understood and carry little risk

• requirements don’t need to be clear from the start • focus groups involving user can be used to gather info without formal documents at first • continuous feedback from client means solution is likely to have excellent usability

• focuses on usability rather than how product works - got good where efficiency is important • regular contact with client must be kept at all times • scales poorly for large projects with big teams

for projects where initial requirements are not fully understood and iterative nature prevents development being side-tracked

• risk management centred • good for high risk projects

• expensive as risk management is a highly specialised skill • if risk analysis done badly, project suffers

• large scale problems that involve high degrees of risk

• emphasises programming so end code is high quality • core principles and processes promote respect and collaboration which is likely to lead to a productive team