Tell me why - About the purpose of architectural work

We face lots of often fierce and confusing debates about architectural work - not only in the agile community. But while all the people endlessly argue about the what, how, when and how much, they forget to ask the most important question: Why?

Why are we doing architectural work in the first place? What is its purpose? Answering this question would render more than 90% of all the debates pointless.

After a short introduction, this slide deck offers three different complementing point of view why we need architectural work, what its purpose is - or at least should be. These points of view can be used to determine if suggested architectural activities really add to the purpose of software architecture or if they are just habits, opinions or beliefs.

As always, the voice track is missing (which can be a bit tricky especially for the third perspective because the accompanying slides consist just of a single quote). Nevertheless, I hope it contains some useful ideas for you.

Transcript

1. Tell me why
   About the purpose of architectural work
   Uwe Friedrichsen – codecentric AG – 2006-2022
   

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2. Uwe Friedrichsen
   Works @ codecentric
   https://twitter.com/ufried
   https://www.speakerdeck.com/ufried
   https://ufried.com/
   

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3. Why we need architectural work
   

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4. Architectural work without asking “why” …
   

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5. BDUF architecture
   Big Design Upfront
   Stack-overflow architecture
   closely related to
   Conference-driven architecture
   Google-driven architecture
   “Agile” architecture
   a.k.a.
   “Emergent” architecture
   often in conjunction with
   “Death to all architects!”
   Developer-centric architecture
   “Strategic” architecture
   often found in conjunction with
   the “Powerpoint architect”
   “Architect” – step
   on the company
   career ladder
   working as fire accelerant
   …
   and many more anti-patterns
   

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6. … results in a mess
   

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7. And how do we try to address the problem?
   

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8. We tend to discuss what architecture is
   instead of asking us why we need it
   or how to work on architecture
   

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9. … which results in even worse archetypes
   

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10. Hype-driven architecture
    

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11. Tunnel-vision architecture
    

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12. Blast-from-the-past architecture
    

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13. One-size-fits-all architecture
    

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14. Accidental architecture
    

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16. We need to ask why to focus our work
    Without asking why the value of our work will be accidental
    

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17. Let’s (re-)establish focus
    

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18. Why do we need architecture?
    • We need architecture to address
    • an optimization problem over time
    • with changing constraints
    

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19. Eh, WTF?
    

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20. Architecture attempts to satisfy quality attributes
    

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21. see, e.g., ISO 25010, ISO 9126 or SEI for comprehensive collections of quality attributes
    Maintainability
    Changeability
    Availability
    Performance
    Scalability
    Functionality
    Security
    …
    Understandability
    Accessibility
    Reliability
    Usability
    Portability
    Operability
    

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22. Quality attributes can be segmented in two general classes
    1. Development (incl. build & test) related attributes
    2. Runtime (usage and operation) related attributes
    

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23. Development related attributes
    • Describe the desired behavior of a system
    from a development perspective
    • Influence how efficiently the system can be modified
    • Target “cost of change”
    • Effectiveness can usually only be measured in hindsight
    • “Arcane guesswork” – subject of many (heated) debates
    à Optimization problem over time
    

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24. Runtime related attributes
    • Describe the desired behavior of a system
    from a usage and operations perspective
    • Target “correctness”
    • Constrain the solution options
    • Support evaluation of solution options
    • May change over time
    à Changing constraints
    

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25. Correctness of behavior
    Runtime (usage and operations) related attributes
    Cost of change
    Development related attributes
    Maintainability
    Changeability
    Availability
    Performance
    Scalability
    Functionality
    Security
    …
    Understandability
    Accessibility
    Reliability
    Usability
    Portability
    Operability
    

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26. Note that cost of change is not sufficient as an optimization goal
    as it neglects all other relevant types of costs.
    Thus, the optimization goal for architectural work
    needs to target the cumulative costs instead.
    (unfortunately, usually not covered by quality attributes)
    

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27. Why do we need architecture?
    • With architecture we attempt
    • to minimize the cumulative costs of a system over its lifetime
    • while ensuring the correctness of behavior at runtime
    

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28. Another perspective …
    

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29. Ideally direct mapping
    Context & needs
    (Problem domain)
    Implementation
    (Solution domain)
    

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30. Context & needs
    (Problem domain)
    Implementation
    (Solution domain)
    Abundance of
    facts and details
    Abundance of
    facts and details
    Too much information
    to cover completely
    Ideally direct mapping
    

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31. Context & needs
    (Problem domain)
    Implementation
    (Solution domain)
    Abundance of
    facts and details
    Abundance of
    facts and details
    Can be covered completely
    Architecture
    Condense and
    structure
    Provide guidance
    and orientation
    

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32. Architecture condenses and structures the
    needs and demands of the problem domain
    to provide guidance and orientation
    in creating the solution
    in order to reduce cognitive load.
    To do so, it typically uses high-level views of required structure
    and behavior, guiding principles, constraints and alike.
    

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33. A final stance …
    

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34. "Ultimately, design is a tool to enhance our humanity”
    -- Ilse Crawford
    

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35. Wrap-up
    

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36. We need architecture to …
    • minimize cumulative costs without violating correctness
    • reduce cognitive load
    • make the lives of the people affected by our solutions better
    

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37. Uwe Friedrichsen
    Works @ codecentric
    https://twitter.com/ufried
    https://www.speakerdeck.com/ufried
    https://ufried.com/
    

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