The Architect's Clue Bucket

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Some Clues: design principles, heuristics, tips, hints...
Organizing Clues: mapping the clue landscape
Getting Clues: where and how to look

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The Architect's Clue Bucket

  1. 1. The architect's clue bucket Ruth Malan
  2. 2. Image source: wikipedia #OReillySACon We are what we think. All that we are arises with our thoughts. With our thoughts we make the world. – The Dhammapada
  3. 3. @RuthMalan #OReillySACon I think about architecture
  4. 4. and what architects do The architect has structural oversight And makes tradeoffs because… there’s only so much rope
  5. 5. and why conveys behavior Structure to delight users at scale across contexts
  6. 6. and more why when there’s tight coupling and bad code smells… … the architect must address The Kludge
  7. 7. and why (again) Because mounting technical debt, ties the system to the past … by its shoelaces
  8. 8. and how Draw on the walls!
  9. 9. and more how iterate and experiment to achieve fit to context and to purpose
  10. 10. Actually, a lot about how
  11. 11. I’m not kidding! DELIBERATE REASON DISCUSS DECIDE RECONSIDER
  12. 12. DELIBERATION, n. The act of examining one's bread to determine which side it is buttered on. REASON, v.t. To weight probabilities in the scales of desire. DISCUSSION, n. A method of confirming others in their errors. DECIDE, v.i. To succumb to the preponderance of one set of influences over another set. RECONSIDER, v. To seek a justification for a decision already made. — Ambrose Bierce, The Devil's Dictionary Well, now I am
  13. 13. But not about drawing on the walls!
  14. 14. @RuthMalan #OReillySACon Where We’re Headed: • some clues: design principles, heuristics, tips, … and hints • organizing clues: mapping the clue landscape • getting clues: where and how to look
  15. 15. @RuthMalan #OReillySACon “Architects must have self-repairing egos” — Dana Bredemeyer
  16. 16. @RuthMalan #OReillySACon The architect’s SCARS: • Separation of Concerns • crisp and resilient Abstractions • balanced distribution of Responsibilities • strive to Simplify — Grady Booch
  17. 17. @RuthMalan #OReillySACon Separation of Concerns “I go along with the natural makeup”… “when I come to the tricky parts, I slow down” — Chuang Tzu: “The Dexterous Butcher”
  18. 18. Layers presentation business logic data access 1996 SCARS: Separation of Concerns application domain
  19. 19. Source: geekandpoke.typepad.com/geekandpoke/2011/03/architectural-best-practices.html (in 2011)
  20. 20. Layers presentation business logic data access 1996 SCARS: Separation of Concerns application domain
  21. 21. — Ambrose Bierce, Devil’s Dictionary ABATIS, n. [1.] Rubbish in front of a fort, to prevent the rubbish outside from molesting the rubbish inside. Image: Engineering and the Mind’s Eye
  22. 22. — Ambrose Bierce, Devil’s Dictionary ABATIS, n. [1.] Rubbish in front of a fort, to prevent the rubbish outside from molesting the rubbish inside. Image: Engineering and the Mind’s Eye “Design things to make their performance as insensitive to the unknown or uncontrollable external influence as practical.” — Eb Rechtin
  23. 23. Image: alistair.cockburn.us/Hexagonal+architecture SCARS: Separation of Concerns Hexagonal Architecture Ports and adapters
  24. 24. Microservices! (in 2016) Image: martinfowler.com/articles/microservices.html
  25. 25. Image: martinfowler.com/bliki/BoundedContext.html Bounded Contexts in DDD SCARS: Separation of Concerns
  26. 26. “There was a wall. It did not look important. It was built of uncut rocks roughly mortared. An adult could look right over it, and even a child could climb it. Where it crossed the roadway, instead of having a gate it degenerated into mere geometry, a line, an idea of boundary. But the idea was real. It was important. For seven generations there had been nothing in the world more important than that wall. Like all walls it was ambiguous, two-faced. What was inside it and what was outside it depended upon which side of it you were on.” — Ursula K. Le Guin, The Dispossessed Image: welshwaller.files.wordpress.com/2013/01/llwest-and-elan-valley-017.jpg
  27. 27. Boundaries: Conway’s Law “Any organization that designs a system (defined broadly) will produce a design whose structure is a copy of the organization's communication structure.” —Melvyn Conway (in 1968!) SCARS: Separation of Concerns
  28. 28. As programmers we deal with abstractions all the time and we have to invent them in order to solve our problems — Michael Feathers SCARS: crisp and resilient Abstractions SCARS: crisp and resilient Abstractions
  29. 29. “The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise.” — Dijkstra SCARS: crisp and resilient Abstractions
  30. 30. Crisp Abstractions Single Responsibility at the level of abstraction of the abstraction SCARS: crisp and resilient Abstractions
  31. 31. SCARS: crisp and resilient Abstractions
  32. 32. Crisp and Resilient Abstractions “We propose instead that one begins with a list of difficult design decisions or design decisions which are likely to change. Each module is then designed to hide such a decision from the others.” — David Parnas SCARS: crisp and resilient Abstractions
  33. 33. Resilient Abstractions Resilient under change SRP: each software module should have one and only one reason to change (Uncle Bob Martin) Retrospective (Feathers) Prospective (thought experiments) SCARS: crisp and resilient Abstractions
  34. 34. @RuthMalan #OReillySACon SCARS: balanced distribution of Responsibilities No “god” component(s)
  35. 35. @RuthMalan #OReillySACon SCARS: strive to Simplify “Simplify, simplify” — H. D. Thoreau ‘One “simplify” would have sufficed’ — Ralph Waldo Emerson, in response
  36. 36. “Simplify, simplify, Simplify” “Communicate, Communicate, Communicate” — Eberhardt Rechtin SCARS: strive to Simplify
  37. 37. “Do the simplest thing that could possibly work” Occam’s Razor: the simplest solution is usually the correct one YAGNI SCARS: strive to Simplify
  38. 38. Chad Fowler: “The older I get, the more I realize the biggest problem to solve in tech is to get people to stop making things harder than they have to be.” Michael Feathers: “It's not that easy.” SCARS: strive to Simplify
  39. 39. SCARS: strive to Simplify
  40. 40. focusing is saying “no”— Steve Jobs GoogleX SCARS: strive to Simplify
  41. 41. “old code doesn’t die; you have to kill it” — Grady Booch SCARS: strive to Simplify
  42. 42. How to kill code StranglerApplication: “An alternative route is to gradually create a new system around the edges of the old, letting it grow slowly over several years until the old system is strangled.” — Martin Fowler SCARS: strive to Simplify
  43. 43. “disorder is easier and more permanent than order, which is difficult and temporary” — Jeremy Campbell SCARS: strive to Simplify
  44. 44. “One bad programmer can easily create two new jobs a year.” — David Parnas SCARS: strive to Simplify
  45. 45. @RuthMalan #OReillySACon The architect’s SCARS: • Separation of Concerns • crisp and resilient Abstractions • balanced distribution of Responsibilities • strive to Simplify — Grady Booch
  46. 46. @RuthMalan #OReillySACon Essence of systems is: • Relationships • Interfaces • Form • Fit • Function — Eberhardt Rechtin
  47. 47. @RuthMalan #OReillySACon Essence of systems is: • Relationships • Interfaces • Form • Fit • Function — Eberhardt Rechtin “Relationships among the elements are what give systems their added value” “Don’t partition by slicing through regions where high rates of information exchange are required””
  48. 48. @RuthMalan #OReillySACon Essence of architecture is: • Structuring • Simplification • Compromise • Balance — Eberhardt Rechtin
  49. 49. “dependencies are a tradeoff between the cost of maintaining the code yourself (and implementing it) & the cost of the risk of breakage” — Kent Beck Balance: Tradeoffs/Compromise
  50. 50. Kent Beck’s 4 Rules of Simple Design • passes its tests • minimises duplication • reveals its intent • has fewer classes/modules/ packages…
  51. 51. More Clues Systemantics by John Gall • New systems mean new problems • A complex system that works is invariably found to have evolved from a simple system that worked • a complex system designed from scratch never works and cannot be made to work • Systems develop goals the minute they come into being
  52. 52. “Uncle Bob” Martin’s SOLID • Single Responsibility Principle (SRP) • Open/Closed Principle (OCP) • Liskov Substitution Principle (LSP) • Interface Segregation Principle (ISP) • Dependency Inversion Principle (DIP) More Clues
  53. 53. 97 Things
  54. 54. 101 Things “Architecture is the thoughtful making of space." -LOUIS KAHN” “Science works with chunks and bits and pieces of things with the continuity presumed, and [the artist] works only with the continuities of things with the chunks and bits and pieces presumed." -ROBERT PIRSIG, ZEN AND THE ART OF MOTORCYCLE MAINTENANCE” “Just because an interesting idea occurs to you doesn't mean it belongs in the building you are designing. Subject every idea, brainstorm, random musing, and helpful suggestion to careful, critical consideration.” ― Matthew Frederick
  55. 55. “If you’re waiting on me to come to a conclusion where I give you a score from one through ten on the NDUF to BDUF scale (and it’s obviously five, right?), you’re going to be disappointed with this post. How much design should you do up front? Dude, I have no idea. Are you building a lunar rover? Probably a lot, then, because the Sea of Tranquility is a pretty unresponsive product owner. Are you cobbling together a minimum viable product and your hardware and business requirements may pivot at any moment? Well, probably not much. I can’t settle your design decisions and timing for you with acronyms or aphorisms.” Erik Dietrich, Designs Don’t Emerge http://www.daedtech.com/designs-dont-emerge/
  56. 56. Is this the part where we get to talk about Technical Wisdom?!
  57. 57. Wisdom factors And factors and refactors
  58. 58. @RuthMalan #OReillySACon Next: • some clues: design principles, heuristics, tips, … and hints • organizing clues: mapping the clue landscape • getting clues: where and how to look
  59. 59. Maps: location, location, location
  60. 60. Maps as places to put things
  61. 61. Context System-in-Context (use, dev, ops) System (Ecosystem) Architecture structure and mechanisms “Requirements” design of system capabilities Strategy ecosystem interventions "Always design a thing by considering it in its next larger context" -- Eliel Saarinen
  62. 62. What ARCHITECTURE STRUCTURE Software architecture refers to the high level structures of a software system, [..] It is the set of structures needed to reason about the software system. Each structure comprises software elements, relations among them, and properties of both elements and relations. —wikipedia/Clements et al
  63. 63. “Good design doesn’t ’emerge’ like a welcome ray of sunshine on a cloudy day. —Erik Dietrich Erik Dietrich, Designs Don’t Emerge http://www.daedtech.com/designs-dont-emerge/
  64. 64. “It comes coughing, sputtering, screaming and grunting from the mud, like a drowning man being pulled from quicksand, and the effort of dragging it laboriously out leaves you exhausted.” Erik Dietrich, Designs Don’t Emerge http://www.daedtech.com/designs-dont-emerge/ Art by Amanda Muledy (@EEKitsabug)
  65. 65. Posit structure Explore behavior Revise structure Explore — with sketches
  66. 66. Factor and Refactor Posit responsibilities Refine as explore behavior and different views Patterns Metaphors Experience Existing stuff “The responsibility of architecture is the architecture of responsibility.” -- Jan van Til
  67. 67. What ARCHITECTURE STRUCTURE interfaces elements and relationships How BEHAVIOR
  68. 68. What ARCHITECTURE STRUCTURE Logical Conceptual Execution
  69. 69. What (system view) HowWhat (user view) SYSTEM ARCHITECTURE STRUCTURALBEHAVIORAL CAPABILITIESCONTEXT Why v v How well FUNCTIONAL PROPERTIES
  70. 70. What (system view) HowWhat (user view) SYSTEM ARCHITECTURE STRUCTURALBEHAVIORAL CAPABILITIESCONTEXT Why v v How well FUNCTIONAL PROPERTIES architecturally significant mechanisms
  71. 71. Architecturally Significant?
  72. 72. Architecturally significant? The demands (forces, properties, …) on the system that are challenging, push the limits, require design attention
  73. 73. Source: Martin Fowler http://martinfowler.com/articles/lmax.html LMAX Disruptor Mechanism Challenges: A trading platform needs very low latency - trades have to be processed quickly because the market is moving rapidly. A retail platform adds complexity because it has to do this for lots of people.
  74. 74. Context System-in-Context (use, dev, ops) System (Ecosystem) Architecture structure and mechanisms “Requirements” design of system capabilities Strategy ecosystem interventions
  75. 75. @RuthMalan #OReillySACon the elephant in the room
  76. 76. Messy! right system built right
  77. 77. Messier! System Design Intent (what should be) System Design Reflection (what is)
  78. 78. Ask “What does the code need?” “What does the system need?” “What does the ecosystem need?”
  79. 79. What (system view) HowWhat (user view) SYSTEM ARCHITECTURE STRUCTURALBEHAVIORAL CAPABILITIESCONTEXT Why v v How well FUNCTIONAL PROPERTIES good?right?successful?
  80. 80. What does it take to be successful?
  81. 81. Tell you a story… it was Alan Kay’s idea! “the Constitution itself is a set of principles for building a very complex dynamic structure that should last for centuries” – Alan Kay
  82. 82. The Virginia Plan Image: ourdocuments.gov
  83. 83. The Constitution of the United States
  84. 84. “I confess that there are several parts of this constitution which I do not at present approve, but I am not sure I shall never approve them: For having lived long, I have experienced many instances of being obliged by better information, or fuller consideration, to change opinions even on important subjects, which I once thought right, but found to be otherwise. It is therefore that the older I grow, the more apt I am to doubt my own judgment, and to pay more respect to the judgment of others.” — Benjamin Franklin
  85. 85. “The Federalist Papers are arguments that support different parts of the design of the Constitution. And the Constitution itself is a set of principles for building a very complex dynamic structure that should last for centuries” – Alan Kay
  86. 86. “it seems to have been reserved to the people of this country, [..], to decide the important question, whether societies of men are really capable or not, of establishing good government from reflection and choice, or whether they are forever destined to depend, for their political constitutions, on accident and force.” Federalist No.1
  87. 87. The Federalist Papers, No. 51 addresses • checks and balances • separation of powers
  88. 88. Areas like • creativity and imagination • empathy, listening and observation • problem framing and solving • perception and bias • experimentation Personal Effectiveness
  89. 89. Areas like • Leadership • Collaboration • Communication and influence • getting things done in organizations • Coach/consultant Organizational Effectiveness “All problems are people problems” — Jerry Weinberg
  90. 90. Areas like • Situational awareness • context mapping • Differentiation and value definition • Direction setting Strategic Effectiveness
  91. 91. @RuthMalan #OReillySACon Next: • some clues: design principles, heuristics, tips, … and hints • organizing clues: mapping the clue landscape • getting clues: where and how to look
  92. 92. Getting Clues: Steal “Experience keeps a dear school, but fools will learn in no other.” Benjamin Franklin Steal: Stand on Shoulders
  93. 93. Shoulders to Stand On Getting Clues: Steal
  94. 94. Shoulders to Stand On Getting Clues: Steal
  95. 95. Shoulders to Stand On Getting Clues: Steal
  96. 96. Getting Clues: Steal Standing on Shoulders: by Analogy
  97. 97. Getting Clues: Steal Shoulders of Giants
  98. 98. @RuthMalan #OReillySACon More Getting Clues • Look • Listen • Ask • Imagine • Play • Draw • Try • Try again • Show • Show again
  99. 99. Getting Clues: Look Large portion of our brain is devoted to visual processing Sighted people see all our waking hours So we see, right?!
  100. 100. Getting Clues: Look “In fact, in medical terms, that’s our view.” — Dan Ariely [joking] “Are we in control of our own decisions?” Dan Ariely
  101. 101. Perception Getting Clues: Look https://www.xkcd.com/32/
  102. 102. Ladder of Inference — Argyris and subsequently Peter Senge in Fifth Discipline Getting Clues: Look
  103. 103. Pyramid of Belief Getting Clues: Look Liminal thinking The pyramid of belief — Dave Gray and self-sealing logic
  104. 104. Selection Getting Clues: Look What we are paying attention to, shapes what we perceive and pay attention to.
  105. 105. Observe: Boyd’s OODA Getting Clues: Look/Observe Observe Orient Decide Act
  106. 106. Observe Orient Decide Act “All architecture is design but not all design is architecture. Architecture represents the significant design decisions that shape a system, where significant is measured by cost of change.” — Grady Booch, blog post, March 2, 2006
  107. 107. Observe Orient Decide Act Getting Clues: Look/Observe Title: short noun phrase Context: describes the forces at play; probably in tension, and should be called out as such Decision: describes our response to these forces Status: proposed, accepted, deprecated or superseded Consequences: describes the resulting context, after applying the decision — Michael Nygard, Documenting Architecture Decisions, Nov 2011
  108. 108. Getting Clues: Look/Change PoV “A change of perspective is worth 80 IQ points” — Alan Kay
  109. 109. Getting Clues: Look/Change PoV Move to different PoV/vantage point • view system through different “lenses” — models (incl. instrumented code), perspectives Also, a matter of discipline • self-discipline, and • discipline of engineering: probe, model, reason, open criticism, come up with counter arguments, come up with alternatives
  110. 110. Getting Clues: Look/Change PoV “You don't understand something until you understand it more than one way” — Marvin Minsky Image: en.wikipedia.org/wiki/Marvin_Minsky#/media/File:Marvin_Minsky_at_OLPCb jpg
  111. 111. “If you haven’t thought of three possibilities, you haven’t thought enough.” — Jerry Weinberg Rule of Three
  112. 112. @RuthMalan #OReillySACon More Getting Clues • Listen • Ask • Empathize • Imagine • Play • Draw • Map • Try • Try again • Show
  113. 113. Context Mapping Getting Clues: Map Image: blog.gardeviance.org/2015/02/an-introduction-to-wardley-value-chain.html Wardley (Value Chain) Maps Grove-styled Context Maps Image: bluesummitstrategy.com
  114. 114. Getting Clues: Map Maps of Code
  115. 115. Getting Clues: Map (Hand-drawn) Maps of Code
  116. 116. Questions Getting Clues: Ask • why? • 5 why’s • what if? why not? • Kipling’s 6 honest serving men
  117. 117. @RuthMalan #OReillySACon More Getting Clues • Listen • Ask • Empathize • Imagine • Play • Draw • Map • Try • Try again • Show
  118. 118. @RuthMalan #OReillySACon Still Getting Clues Ruth Malan Web: bredemeyer.com also: ruthmalan.com Twitter: @ruthmalan

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