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BK - Spring 2006. Software Development: Terminology. Systems Analysis:Process of seeking to understand organization of systemInvestigation and modelling of system requirementsSoftware Design:Process of producing solution to analysed requirementsSpecifying detail of how system will meet requirem
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1. BK - Spring 2006 Lecture 2: Software Development Software Development Terminology
Design Objectives and Design Problems
Why Do Things Go Wrong?
Project Life Cycles
The waterfall model
The spiral model
The Unified Process
2. BK - Spring 2006 Software Development:Terminology Systems Analysis:
Process of seeking to understand organization of system
Investigation and modelling of system requirements
Software Design:
Process of producing solution to analysed requirements
Specifying detail of how system will meet requirements
Software Engineering:
Application of a systematic, disciplined approach
Adherence to high standards of professional ethics
3. BK - Spring 2006 What Do We Need? We need software that is:
Useful and usable: ‘fit for purpose’
Reliable: free of bugs
Flexible: can adapt to changing needs of users
Affordable: to buy and to maintain
Available: delivered, portable and maintainable
Objectives are:
Easy to state, but…
…may be hard to achieve in practice!
4. BK - Spring 2006 When Programs Go Wrong Total failure of software:
The London Ambulance Service
TAURUS stock trading system
ARIANE 5 Launcher
August 14th 2003, east coast USA power blackout
Failure can be catastrophic and very costly
but, it’s the exception rather than the rule
Nature of problem depends on stakeholder you ask
The end users
The ‘clients’
The software developers Examples: London Ambulance Service: automated dispatch service unable to cope with high rate of calls began to lose track of ambulance locations with disastrous results. May have resulted in deaths as ambulances failed to turn up. London Stock Exchange Taurus System: aborted after five years with an estimated bill of around 450 million pounds. Ariane 5: maiden flight on June 4, 1996 ended when launcher exploded due to a series of software errors. East Coast USA power outage: software failure at a power provider “may have contributed significanlty to the outage” according to Computer World magazine.Examples: London Ambulance Service: automated dispatch service unable to cope with high rate of calls began to lose track of ambulance locations with disastrous results. May have resulted in deaths as ambulances failed to turn up. London Stock Exchange Taurus System: aborted after five years with an estimated bill of around 450 million pounds. Ariane 5: maiden flight on June 4, 1996 ended when launcher exploded due to a series of software errors. East Coast USA power outage: software failure at a power provider “may have contributed significanlty to the outage” according to Computer World magazine.
5. BK - Spring 2006