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Y Cathedral Bazaar and Bridge are competing Software Engineering Metaphors

Y Cathedral Bazaar and Bridge are competing Software Engineering Metaphors. SERG Software Engineering Research Group University of Auckland. Presentation by Wolfgang Fahl, BIT Plan 2008-11-28. Agenda. Introduction: W. Fahl/BITPlan What are Metaphors & Maxims?

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Y Cathedral Bazaar and Bridge are competing Software Engineering Metaphors

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  1. Y Cathedral Bazaar and Bridge are competing Software Engineering Metaphors SERGSoftware Engineering Research GroupUniversity of Auckland Presentation by Wolfgang Fahl, BITPlan2008-11-28

  2. Agenda • Introduction: W. Fahl/BITPlan • What are Metaphors & Maxims? • Software Engineering Metaphors & Maxims – a guided tour • Raffle • Summary & Conclusion • Discussion

  3. Wolfgang Fahl • Wolfgang Fahl • Computer ScientistRWTH Aachen, Germany • President iSAQB • CEO BITPlan

  4. Agenda • Introduction: W. Fahl/BITPlan • What are Metaphors & Maxims? • Software Engineering Metaphors & Maxims – a guided tour • Raffle • Summary & Conclusions • Discussion

  5. What is a Metaphor? • describe one thing by using another thing (the metaphor) as a helping device to do so • knowledge of implicit and explicit attributes of the metaphor is used to „transfer“ this knowledge to the target subject • differences cause a dilemma – they can be useful if discussed and harmful if they are not recognized

  6. What is a Maxim? • GuidelineNon mandatory streamline of particular processes according to a set routine • MoralMessage conveyed or learned from a story or event • MaximA principle or rule. A wise saying to advise a recommended course of conduct

  7. Agenda • Introduction: W. Fahl/BITPlan • What are metaphors & guidelines? • Software Engineering Metaphors & Maxims – a guided tour • Raffle • Summary & Conclusions • Discussion

  8. SE Metaphors & Maxims • It‘s broken anyway • Phaedrus‘s knife • Architecture • The Cathedral • Engineering • The Bridge • The Factory • The Y • The Bazaar

  9. It‘s broken anyway • The software is broken anyway ... • How can we make sure it doesn‘t harm anybody?

  10. Phaedrus‘s knife What is Analysis? Three methods of organization that pervade all human thinking: • Objects - Attributes • Whole - Part • Groups – Members

  11. Phaedrus‘s knife:Analysis • Model – a representation of the real world • Model – a construction plan

  12. Architecture • Loads • Materials • Style • Purpose • Optimization

  13. The Cathedral „Have you drawn your plans, Tom Builder?“

  14. In the 10 th century buildings where created using rough stones, which were put together to thick walls using mortar. Castles: rough stones

  15. The stones are unevenly shaped and the individually distributed mortar creates the connection between them. Gaps are filled manually

  16. Walls created from precisely cut stones are lighter and still more stable. This approach leads to higher, more beautiful and less costly* buildings Cathedrals - cut stones * it‘s possible to add more extra art and glass now

  17. Before and during build time master builder and owner discuss details using models Planning leads to predictability and feasibility A style emerges Model, Planning, Style

  18. The result speaks for itself

  19. What did the creators of the Eiffel tower know about the finished tower at the time when this picture was taken? Engineering

  20. The Forth Bridge is overdesigned since the builders could not exactly tell how much material was necessary for a long term safe and reliable operation Too much of a good thing

  21. The Bridge

  22. The Bridge Bridge between man and computer

  23. The abstraction trap More abstraction does not lead to closing the gap between humans and the computer

  24. The Factory • Mass production • Lean production • Quality control • Built-to-order • Service centered selling

  25. Domain specific Requirements Technical Requirements Y DomainModel ArchitectureModel Mapping rules ImplementationDomain code uses architecture code The Y-Principle PIM PDescM PSM (only implicit)

  26. The Cathedral & the BazaarThe Linux success Homesteading the Nusphereproperty and ownership customs of the OSS community The magic cauldron Tragedy of the commons – the inverse commonsOSS economy The Bazaar

  27. Agenda:Raffle • Introduction: W. Fahl/BITPlan • What are metaphors & guidelines? • Software Engineering Metaphors & Maxims – a guided tour • Raffle • Summary & Conclusions • Discussion

  28. Agenda • Introduction: W. Fahl/BITPlan • What are metaphors & guidelines? • Software Engineering Metaphors & Guidelines – a guided tour • Raffle • Summary & Conclusions • Discussion

  29. Summary • Shift towards Architecture / Engineering • Models as balance of analysis result & construction plan • „Real world“ projects don‘t seem to fit the methapors (yet?) • Metaphors are a common approach to describe complex interactions (Jazz-Band/Orchestra, ... Lego, ...)

  30. Conclusions • Decision making is the key process in software engineering • The shown Maxims and Metaphors give an idea for possible decision making approaches

  31. Agenda • Introduction: W. Fahl/BITPlan • What are metaphors & guidelines? • Software Engineering Metaphors & Maxims – a guided tour • Summary & Conclusions • Discussion

  32. Enjoy your software project! Pater-Delp-Str. 1 D-47877 Willich Germany Fon +49 2154 811-480, Fax –481 http://www.bitplan.commailto:info@bitplan.com

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