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Transcript of © BITPlan GmbH, 2008 - 2008-11-28Page 1/32 of Y Cathedral Bazaar and Bridge Y Cathedral Bazaar and...
© BITPlan GmbH, 2008 - 2008-11-28Page 1/
32 of Y Cathedral Bazaar and Bridge
Y Cathedral Bazaar and Bridge are competing Software Engineering
Metaphors
SERGSERGSoftware Engineering Research GroupSoftware Engineering Research Group
University of AucklandUniversity of Auckland
Presentation by Wolfgang Fahl, Presentation by Wolfgang Fahl, BITPlan2008-11-282008-11-28
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Agenda
Introduction: W. Fahl/BITPlan • What are Metaphors & Maxims?• Software Engineering Metaphors &
Maxims – a guided tour• Raffle• Summary & Conclusion• Discussion
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Wolfgang Fahl
• Wolfgang Fahl
• Computer ScientistRWTH Aachen, Germany
• President iSAQB
• CEO BITPlan
S M A R T S OL U T I N SO
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Agenda
• Introduction: W. Fahl/BITPlan What are Metaphors & Maxims?• Software Engineering Metaphors &
Maxims – a guided tour• Raffle• Summary & Conclusions• Discussion
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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
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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
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Agenda
• Introduction: W. Fahl/BITPlan • What are metaphors & guidelines?Software Engineering Metaphors &
Maxims – a guided tour• Raffle• Summary & Conclusions• Discussion
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SE Metaphors & Maxims
• It‘s broken anyway• Phaedrus‘s knife• Architecture• The Cathedral• Engineering• The Bridge• The Factory• The Y• The Bazaar
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It‘s broken anyway
• The software is broken anyway ...
• How can we make sure it doesn‘t harm anybody?
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Phaedrus‘s knife
What is Analysis?
Three methods of organization that pervade all human thinking:
2. Whole - Part
3. Groups – Members
1. Objects - Attributes
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COMPONENTS
MOTORCYCLE
FUNCTIONS
Phaedrus‘s knife:Analysis
• Model – a representation of the real world COMPONENTS
MOTORCYCLE
FUNCTIONS
POWER ASSEMBLY RUNNING ASSEMBLY• Model – a construction plan
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Architecture
• Loads
• Materials
• Style
• Purpose
• Optimization
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The Cathedral
„Have you drawn your plans, Tom Builder?“
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Castles: rough stones
• In the 10 th century buildings where created using rough stones, which were put together to thick walls using mortar.
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Gaps are filled manually
• The stones are unevenly shaped and the individually distributed mortar creates the connection between them.
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Cathedrals - cut stones
• Walls created from precisely cut stones are lighter and still more stable.
• This approach leads to higher, more beautiful and less costly* buildings
* it‘s possible to add more extra art and glass now
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Model, Planning, Style
• Before and during build time master builder and owner discuss details using models
• Planning leads to predictability and feasibility
• A style emerges
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The result speaks for itself
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Engineering
• What did the creators of the Eiffel tower know about the finished tower at the time when this picture was taken?
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Too much of a good thing
• 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
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The Bridge
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The Bridge
Bridge between
man and
computerHumans Machine© BITPlan, 2000expected delivered
asked for
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The abstraction trap
More abstraction
does not lead to
closing the gap
between humans
and the computer
Machine
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© BITPlan, 2000
IdeasWishesExpectationsFeelings
Bits und
Bytes
Humans
Binary code
Assembler
ProceduralLanguages
objekt orientedLanguages
ModelLanguages
Meta-Languages
Meta-Meta-Languages
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The Factory
• Mass production
• Lean production
• Quality control
• Built-to-order
• Service centered selling
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Domain specificRequirements
TechnicalRequirements
DomainModel
ArchitectureModel
Mapping rules
ImplementationDomain code uses architecture code
The Y-Principle
PIM PDescM
PSM (only implicit)
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The Bazaar
• 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
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Agenda:Raffle
•Introduction: W. Fahl/BITPlan
•What are metaphors & guidelines?
•Software Engineering Metaphors & Maxims – a guided tour
Raffle
•Summary & Conclusions
•Discussion
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Agenda
• Introduction: W. Fahl/BITPlan • What are metaphors & guidelines?• Software Engineering Metaphors &
Guidelines – a guided tour• RaffleSummary & Conclusions• Discussion
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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, ...)
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Conclusions
• Decision making is the key process in software engineering
• The shown Maxims and Metaphors give an idea for possible decision making approaches
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Agenda
• Introduction: W. Fahl/BITPlan
• What are metaphors & guidelines?• Software Engineering Metaphors &
Maxims – a guided tour• Summary & ConclusionsDiscussion
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Pater-Delp-Str. 1 D-47877 Willich Germany
Fon +49 2154 811-480, Fax –481
http://www.bitplan.commailto:[email protected]
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