Modelling Heuristics - Speaker Deck

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Modelling Heuristics @mathiasverraes

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Mathias Verraes Independent Consultant Value Object Comm.V Student of Systems Meddler of Models Labourer of Legacy verraes.net

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Is modelling a learnable skill?

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The pain of a wrong abstraction

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Upfront Model? 1 1 Scott W. Ambler, "Big Modeling Up Front (BMUF) Anti-Pattern", http://www.agilemodeling.com/ essays/bmuf.htm

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You are always making mental models

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Analysis model 2 vs Domain model 2 Martin Fowler, 1996, "Analysis Patterns: Reusable Object Models"

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Heuristic Domain Language

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Linguistic Relativism Sapir-Whorf Hypothesis 3,4 4 Paul Graham, "Beating the Averages", http://www.paulgraham.com/avg.html 3 Steven Pinker, 1994, "The Language Instinct"

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Heuristic Find the Nouns Anti-pattern?

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Heuristic Descriptive vs Influential Properties

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[ { "licensePlate": "1-ABC-123", "brand": "BMW", "make": "X1", "color": "Aggregate Blue", ..., "location": "40.7127837,-74.0059413" }, ... ]

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Heuristic Static / Dynamic

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Heuristic Find the Verbs Commands

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Verb-based: f = chain( breakTextIntoWords() : [String] groupWordsIntoLines() : [[String]] joinWordsInBrokenLines() : [String] joinBrokenLines() : String ) f("A long paragraph") -> "A long\nparagraph"

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Noun-based: 7 f = chain( words() : [String] brokenLines() : [[String]] wordJoinedLines() : [String] joinedLines() : String ) f("A long paragraph") -> "A long\nparagraph" 7 Michael Feathers, "A Type Driven Approach to Functional Design", InfoQ

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Heuristic Find the Sentences Find the Idioms

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Heuristic Find the Scenarios

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Given I have a product When I look at the price of a product ... or Given I have a product When I lookup the product in the pricing table ... ?

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Remember, you are always making mental models

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As a customer I want to ... Given there is a product When I look at the price of a product ... As a shop owner I want to ... Given I have a product When I lookup the product in the pricing table ...

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Heuristic Actors and Roles

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Heuristic The Worker and the Beneficiary

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When I look at the price of a product ... When I lookup the product in the pricing table ...

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Heuristic Segregating Reading and Writing

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Heuristic Being Behaving Becoming Three B's 5 5 Gerald M. Weinberg, 1988, "Rethinking Systems Analysis and Design"

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The customer sometimes has an email. Missing concept?

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Heuristic Collaborative Construction6 Execution Tracking aka Planning/Execution/Analysis 6 Cyrille Martraire, "Collaborative Construction by Alberto Brandolini", http:// cyrille.martraire.com/2012/09/collaborative-construction-by-alberto-brandolini/

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Heuristic Domain Events8 8 http://verraes.net/2014/11/domain-events/

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Time ->

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Heuristic Cause & Consequence

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Cause & Consequence Human External system Process Time

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Heuristic Business Rules Reasons for failure

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Heuristic Consistency Boundary

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Heuristic Entity Inclusion

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Heuristic Temporal Expansion

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Heuristic Temporal Shift

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Heuristic Invariant Inclusion

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Heuristic Conceptual Shift

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Heuristic Crossing Streams

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Heuristic Happy Path / Divergent Path9 9 Mathias Verraes, "Event Storming: on Fake Domains and Happy Paths", http://verraes.net/ 2014/07/event-storming-fake-domains-happy-paths/

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Formal Informal Aformal

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Throw Away the Model

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@mathiasverraes verraes.net Workshops Domain-Driven Design verraes.net/workshops Ghent, Belgium, January 20-22 Newcastle, UK (TBC)