COMP 2007 R J Walters

COMP Last time Software Engineering is important It is “soft” - Not easy Making things using an “engineering” approach Building good systems People working in teams We don’t have all the answers

COMP Today General comments on documentation Requirements

COMP Documentation Shouldn’t be an afterthought Defines your process Includes: Requirements Design Code Testing User manuals Other things

COMP Documentation You have already seen what you need UML Remember what you are doing it for So you know what you are doing Smooth operation of your team So others can see what you did An aid to maintenance Because the clients asked for it

COMP Documentation - style High/low ceremony Do you want/need copious supporting evidence for everything? Would something informal be appropriate? Something in between? Fix it up later? “Faking it” A Rational Design Process: How and why to fake it - David L. Parnas (and others)

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Requirements Why do they matter? What are they? Techniques

COMP Why do requirements matter? Starting point for what you are going to make Form the basis of your contract with the client They are what you test against

COMP What are requirements? The definition of what the required system should do Who it is for, what it does, what it looks like, what it does who will use it … Don’t forget Non Functional Requirements …

COMP Techniques You have seen this before In UML Use cases Sequence diagrams … Other methods possible Structured English

COMP Where does it go wrong? Clients and developers struggle to communicate Clients ask for what they think you can deliver Developers offer what they think the client wants Moving target Need for management

COMP Spiral model fits here Diagram by from Software Engineering 7 by Ian Sommerville

COMP Requirements - Observations Historically there wasn’t much need First machines built to solve specific problems (Eniac, Colossus) Done badly (or not at all) Lack of clarity and precision Misunderstandings Errors Creep

COMP Summary Software Engineering is … Documentation Requirements

COMP Questions? Suggested reading Your UML reference Software Engineering, 7th Edition, Ian Sommerville Software Engineering: A Practitioner's Approach, Roger Pressman

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