The Fractal Geometry of Software Design

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vladikk doit-intl.com #DDDEU THE FRACTAL GEOMETRY OF SOFTWARE DESIGN

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@vladikk vladikk.com [email protected] VLADIK (VLAD)   KHONONOV

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vladikk doit-intl.com #DDDEU

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vladikk doit-intl.com #DDDEU • How much food do we need to stay alive? • How creative are we? • How profitable are our companies?

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vladikk doit-intl.com #DDDEU West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson. How much food do we need to stay alive? How creative are we? How profitable are our companies?

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vladikk doit-intl.com #DDDEU METABOLIC RATE OF ANIMALS West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU REGISTERED PATENTS West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson. INCOME AND ASSETS OF COMPANIES

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vladikk doit-intl.com #DDDEU West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU METABOLIC RATE OF ANIMALS West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU "Viewed through this lens, cities, companies, plants, animals, our bodies, and even tumors manifest a remarkable similarity in the ways that they are organized and function." - Geo ff rey West

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vladikk doit-intl.com #DDDEU

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vladikk doit-intl.com #DDDEU AGENDA 1. A primer on energy supply networks 2. How network theory applies to software design 3. Leveraging the network theory to manage complexity 4. S ^ D

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vladikk doit-intl.com #DDDEU ENERGY SUPPLY   NETWORKS

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vladikk doit-intl.com #DDDEU ENERGY SUPPLY NETWORKS Systems that are sustained by the transport of energy through hierarchical networks.

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vladikk doit-intl.com #DDDEU ENERGY SUPPLY NETWORKS

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vladikk doit-intl.com #DDDEU ENERGY SUPPLY NETWORKS

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vladikk doit-intl.com #DDDEU SOFTWARE DESIGN AS AN ENERGY SUPPLY NETWORK

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vladikk doit-intl.com #DDDEU WHAT IS THE ENERGY SUPPLIED BY SOFTWARE DESIGN?

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vladikk doit-intl.com #DDDEU WHAT IS THE ENERGY SUPPLIED BY SOFTWARE DESIGN? — KNOWLEDGE

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vladikk doit-intl.com #DDDEU

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vladikk doit-intl.com #DDDEU Shared Knowledge Encapsulated   Knowledge Boundaries Encapsulated   Knowledge

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vladikk doit-intl.com #DDDEU KNOWLEDGE: THE ENERGY OF SOFTWARE DESIGN Implementation Coupling Functional Coupling Model Coupling Contract Coupling

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vladikk doit-intl.com #DDDEU KNOWLEDGE: THE ENERGY OF SOFTWARE DESIGN Implementation Coupling Functional Coupling Model Coupling Contract Coupling • How the parts of the system are implemented • Private interfaces • Not intended for inter-component integration

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vladikk doit-intl.com #DDDEU KNOWLEDGE: THE ENERGY OF SOFTWARE DESIGN Implementation Coupling Functional Coupling Model Coupling Contract Coupling • Knowledge of what the system has to do • Business logic • Use cases • Rules, invariants, constraints

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vladikk doit-intl.com #DDDEU KNOWLEDGE: THE ENERGY OF SOFTWARE DESIGN Implementation Coupling Functional Coupling Model Coupling Contract Coupling • Models of the business domain • Data structures • Software system-related aspects of the business domain • Understanding of the functional requirements

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vladikk doit-intl.com #DDDEU KNOWLEDGE: THE ENERGY OF SOFTWARE DESIGN Implementation Coupling Functional Coupling Model Coupling Contract Coupling • Components’ integration contracts • Integration-specific models, APIs • The minimal data needed for components to work together

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vladikk doit-intl.com #DDDEU “System design is inherently about boundaries (what’s in, what’s out, what spans, what moves between), and about tradeo ff s. It reshapes what is outside, just as it shapes what is inside.” - Ruth Malan (@ruthmalan)

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vladikk doit-intl.com #DDDEU KNOWLEDGE: THE ENERGY OF SOFTWARE DESIGN Knowledge vs Data: TBs of data across a contract-based interface vs   a few bytes across implementation-coupled modules

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vladikk doit-intl.com #DDDEU KNOWLEDGE: THE ENERGY OF SOFTWARE DESIGN So ft ware systems are sustained by the transport of knowledge (energy) through hierarchical networks of modules.

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vladikk doit-intl.com #DDDEU ECONOMIES OF SCALE IN   ENERGY SUPPLY NETWORKS

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vladikk doit-intl.com #DDDEU West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU METABOLIC RATE OF ANIMALS West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU METABOLIC RATE OF ANIMALS West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU y = 3.4 * x3/4 West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU y = 3.4 * x3/4 y = x Sublinear   Growth Linear   Growth Sublinear function grows slower than any linear function

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vladikk doit-intl.com #DDDEU Chihuahua Yorkshire Terrier Pug Beagle Boxer Newfoundland 1.8kg 3.5kg 7kg 14.5kg 29kg 58kg

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vladikk doit-intl.com #DDDEU Chihuahua Yorkshire Terrier Pug Beagle Boxer Newfoundland 1.8kg 3.5kg 7kg 14.5kg 29kg 58kg BASAL METABOLIC RATE The minimum number of calories a day needed   to stay alive without performing any activities. https://www.sciencedirect.com/topics/engineering/basal-metabolic-rate

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vladikk doit-intl.com #DDDEU Chihuahua Yorkshire Terrier Pug Beagle Boxer Newfoundland 1.8kg 3.5kg 7kg 14.5kg 29kg 58kg 110 220 440 880 1,760 3,520 Breed Weight Basal   Metabolic   Rate

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vladikk doit-intl.com #DDDEU Chihuahua Yorkshire Terrier Pug Beagle Boxer Newfoundland 1.8kg 3.5kg 7kg 14.5kg 29kg 58kg 110 220 440 880 1,760 3,520 110 180 302 521 876 1,474 Breed Weight Linear Thinking Basal   Metabolic   Rate

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vladikk doit-intl.com #DDDEU West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson. NO. OF GASOLINE STATIONS

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vladikk doit-intl.com #DDDEU West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU REGISTERED PATENTS West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU y = x1.15 y = x West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson.

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vladikk doit-intl.com #DDDEU y = x1.15 y = x Superlinear   Growth Linear   Growth Superlinear function grows faster than any linear function

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vladikk doit-intl.com #DDDEU ECONOMIES OF SCALE Superlinear   Growth Sublinear   Growth Linear   Growth

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vladikk doit-intl.com #DDDEU KNOWLEDGE: THE ENERGY OF SOFTWARE DESIGN So ft ware systems are sustained by the transport of knowledge (energy) through hierarchical networks of modules.

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vladikk doit-intl.com #DDDEU Knowledge (sublinear growth) Functionality (Linear growth)

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vladikk doit-intl.com #DDDEU ECONOMIES OF SCALE Superlinear   Growth Sublinear   Growth Linear   Growth

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vladikk doit-intl.com #DDDEU ECONOMIES OF SCALE Superlinear  

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vladikk doit-intl.com #DDDEU GROWTH LIMITS

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vladikk doit-intl.com #DDDEU "You can plainly see the impossibility of increasing the size of structures to vast dimensions either in art or in nature; … also it would be impossible to build up the bony structures of men, horses, or other animals so as to hold together and perform their normal functions . . . for if his height be increased inordinately he will fall and be crushed under his own weight.” - Galileo Galilei

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vladikk doit-intl.com #DDDEU

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vladikk doit-intl.com #DDDEU

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vladikk doit-intl.com #DDDEU Cross-section Resistance to fracture is proportional to the cross-sectional area

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vladikk doit-intl.com #DDDEU x2 x2 x2 Weight increase: Strength increase: 2 * 2 * 2 = x8 2 * 2 = x4

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vladikk doit-intl.com #DDDEU

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vladikk doit-intl.com #DDDEU GROWTH LIMITS Superlinear   Growth Sublinear   Growth Linear   Growth • As a system grows, it becomes more efficient • Undesired consequences of growth become more efficient as well

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vladikk doit-intl.com #DDDEU ORGANISMS • Limbs are unable to support the overall weight • The amount of cells surpasses capillaries’ ability to supply energy • All available energy used for repairing consequences of entropy CITIES • Overcrowding • Crime rates • Pollution • Spread of diseases COMPANIES • Sublinear scaling of sales, incomes, and profits • Bureaucracy • Administration and management complexity SOFTWARE SYSTEMS ?

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vladikk doit-intl.com #DDDEU GROWTH LIMITS IN SOFTWARE SYSTEMS

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vladikk doit-intl.com #DDDEU Knowledge (sublinear growth) Functionality (Linear growth)

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vladikk doit-intl.com #DDDEU M8 M10 M9 M6 M1 M2 M3 M4 M5 M7

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vladikk doit-intl.com #DDDEU Knowledge (sublinear growth) Complexity (superlinear growth) Cognitive Limit (No growth) Functionality (Linear growth)

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vladikk doit-intl.com #DDDEU Knowledge Miller, G. A. (1994). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 101(2), 343–352 ESTIMATED CAPACITY FOR PROCESSING INFORMATION 2000s: 4 +/- 1 Cowan, Nelson. "The magical number 4 in short-term memory: A reconsideration of mental storage capacity." Behavioral and brain sciences 24.1 (2001): 87-114.

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vladikk doit-intl.com #DDDEU Knowledge (sublinear growth) Complexity (superlinear growth) Cognitive Limit (No growth) Functionality (Linear growth)

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vladikk doit-intl.com #DDDEU Knowledge - Galileo Galilei

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vladikk doit-intl.com #DDDEU Knowledge (sublinear growth) Complexity (superlinear growth) Cognitive Limit (No growth) Functionality (Linear growth)

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vladikk doit-intl.com #DDDEU EXTENDING GROWTH LIMITS

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vladikk doit-intl.com #DDDEU “I have sketched a bone whose natural length has been increased three times and whose thickness has been multiplied until, for a correspondingly large animal, it would perform the same function which the small bone performs for its small animal” - Galileo Galilei

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vladikk doit-intl.com #DDDEU “if one wishes to maintain in a great giant the same proportion of limb as that found in an ordinary man he must find a harder and stronger material for making the bones” - Galileo Galilei

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vladikk doit-intl.com #DDDEU POSTPONING GROWTH LIMITS 1. Adapt form / shape to withstand increased stress 2. Use stronger materials

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vladikk doit-intl.com #DDDEU SUSTAINABLE GROWTH   REQUIRES INNOVATION

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vladikk doit-intl.com #DDDEU ORGANISMS • Limbs are unable to support the overall weight • Crime rates • Pollution • Spread of diseases COMPANIES • Sublinear scaling of sales, incomes, and profits

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vladikk doit-intl.com #DDDEU https://en.wikipedia.org/wiki/List_of_largest_cities_throughout_history

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vladikk doit-intl.com #DDDEU https://en.wikipedia.org/wiki/List_of_largest_cities_throughout_history Stone tools, Fire, Bow, Wheel Writing Water   Mill Gunpowder Printing Press Optical Lens Steam   Engine Telegraph Plastics Airplane Transistor Nuclear Power Space Flight Internet Mobile Technology

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vladikk doit-intl.com #DDDEU "Technology can bring benefits if, and only if, it diminishes a limitation’" - Eliyahu M. Goldratt

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vladikk doit-intl.com #DDDEU INNOVATION IN SOFTWARE DESIGN

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vladikk doit-intl.com #DDDEU Knowledge (sublinear growth) Complexity (superlinear growth) Cognitive Limit (No growth) Functionality (Linear growth) Cognitive Limit (superlinear growth)

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vladikk doit-intl.com #DDDEU "Highly complex, self-sustaining structures, whether cells, organisms, ecosystems, cities, or corporations, require the close integration of enormous numbers of their constituent units that need e ff icient servicing at all scales. This has been accomplished in living systems by evolving fractal-like, hierarchical branching network systems.” - Geo ff rey West

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vladikk doit-intl.com #DDDEU

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vladikk doit-intl.com #DDDEU

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vladikk doit-intl.com #DDDEU

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vladikk doit-intl.com #DDDEU http://paulbourke.net/fractals/googleearth/

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vladikk doit-intl.com #DDDEU Y. Chen, P. Cheng, Heat transfer and pressure drop in fractal tree-like microchannel nets Lorthois, Sylvie, and Francis Cassot. "Fractal analysis of vascular networks: insights from morphogenesis." Journal of theoretical biology 262.4 (2010): 614-633.

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vladikk doit-intl.com #DDDEU https://opte.org Klinkhamer, Christopher, et al. "Functionally fractal urban networks: Geospatial co-location and homogeneity of infrastructure."

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vladikk doit-intl.com #DDDEU

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vladikk doit-intl.com #DDDEU West, G. (2018). Scale: The universal laws of life and death in organisms, cities and companies. Weidenfeld & Nicolson. NO. OF GASOLINE STATIONS

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vladikk doit-intl.com #DDDEU Sublinear   Growth Linear   Growth Sublinear function grows slower than any linear function

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vladikk doit-intl.com #DDDEU Knowledge (sublinear growth) Complexity (superlinear growth) Cognitive Limit (No growth) Functionality (Linear growth) Complexity Sublinear growth)

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vladikk doit-intl.com #DDDEU FRACTAL MODULARITY

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vladikk doit-intl.com #DDDEU KNOWLEDGE: THE ENERGY OF SOFTWARE DESIGN Implementation Coupling Functional Coupling Model Coupling Contract Coupling Shared Knowledge Encapsulated   Knowledge Boundaries Encapsulated   Knowledge

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vladikk doit-intl.com #DDDEU KNOWLEDGE: THE ENERGY OF SOFTWARE DESIGN So ft ware systems are sustained by the transport of knowledge (energy) through hierarchical networks of modules.

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vladikk doit-intl.com #DDDEU Y. Chen, P. Cheng, Heat transfer and pressure drop in fractal tree-like microchannel nets

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vladikk doit-intl.com #DDDEU Knowledge (sublinear growth) Complexity (superlinear growth) Cognitive Limit (No growth) Functionality (Linear growth)

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vladikk doit-intl.com #DDDEU Knowledge

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vladikk doit-intl.com #DDDEU

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vladikk doit-intl.com #DDDEU INTEGRATION STRENGTH (S) Implementation Coupling Functional Coupling Model Coupling Contract Coupling Shared Knowledge Encapsulated   Knowledge Boundaries Encapsulated   Knowledge

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vladikk doit-intl.com #DDDEU DISTANCE (D) Downstream Module Upstream Module depends on Distance

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vladikk doit-intl.com #DDDEU DISTANCE (D) M ethods Classes Sub-M odules M odules Com ponents (M icro)Services System s Coordination

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vladikk doit-intl.com #DDDEU COST OF CHANGE IS PROPORTIONAL TO THE DISTANCE BETWEEN COMPONENTS

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vladikk doit-intl.com #DDDEU Downstream Module Upstream Module depends on Integration Strength (S) Distance (D)

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vladikk doit-intl.com #DDDEU LOW STRENGTH HIGH STRENGTH LOW DISTANCE HIGH DISTANCE

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vladikk doit-intl.com #DDDEU LOW STRENGTH HIGH STRENGTH ? LOW DISTANCE HIGH DISTANCE • High cost of cascading changes • Low shared knowledge • Minimizes cascading changes

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vladikk doit-intl.com #DDDEU LOW STRENGTH HIGH STRENGTH Loose Coupling LOW DISTANCE HIGH DISTANCE • High cost of cascading changes • Low shared knowledge • Minimizes cascading changes

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vladikk doit-intl.com #DDDEU LOW STRENGTH HIGH STRENGTH ? Loose Coupling LOW DISTANCE HIGH DISTANCE • High shared knowledge • Frequent cascading changes • Low cost of cascading changes

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vladikk doit-intl.com #DDDEU LOW STRENGTH HIGH STRENGTH High   Cohesion Loose Coupling LOW DISTANCE HIGH DISTANCE • High shared knowledge • Frequent cascading changes • Low cost of cascading changes

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vladikk doit-intl.com #DDDEU High   Cohesion LOW STRENGTH HIGH STRENGTH ? Loose Coupling LOW DISTANCE HIGH DISTANCE • Low cost of cascading changes • Low shared knowledge • Co-located unrelated modules

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vladikk doit-intl.com #DDDEU High   Cohesion LOW STRENGTH HIGH STRENGTH Local   Complexity Loose Coupling LOW DISTANCE HIGH DISTANCE • Low cost of cascading changes • Low shared knowledge • Co-located unrelated modules

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vladikk doit-intl.com #DDDEU High   Cohesion LOW STRENGTH HIGH STRENGTH Local   Complexity Loose Coupling ? LOW DISTANCE HIGH DISTANCE • High cost of cascading changes • High shared knowledge • Frequent cascading changes

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vladikk doit-intl.com #DDDEU High   Cohesion LOW STRENGTH HIGH STRENGTH Local   Complexity Loose Coupling Global   Complexity LOW DISTANCE HIGH DISTANCE • High cost of cascading changes • High shared knowledge • Frequent cascading changes

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vladikk doit-intl.com #DDDEU Local Complexity

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vladikk doit-intl.com #DDDEU Global Complexity

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vladikk doit-intl.com #DDDEU High   Cohesion LOW STRENGTH HIGH STRENGTH Local   Complexity Loose Coupling Global   Complexity LOW DISTANCE HIGH DISTANCE

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vladikk doit-intl.com #DDDEU High   Cohesion LOW STRENGTH HIGH STRENGTH Local   Complexity Loose Coupling Global   Complexity LOW DISTANCE HIGH DISTANCE

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vladikk doit-intl.com #DDDEU High

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vladikk doit-intl.com #DDDEU High

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vladikk doit-intl.com #DDDEU High

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vladikk doit-intl.com #DDDEU 1. Minimize integration strength as much as possible 2. Balance integration strength and distance • Both are high? — Reduce distance • Both are low? — Increase distance APPLYING M=S^D

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vladikk doit-intl.com #DDDEU Implementation Functional Model Contract INTEGRATION STRENGTH

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vladikk doit-intl.com #DDDEU Strength:   Contract M=S^D IN DOMAIN-DRIVEN DESIGN Distance Bounded Context Bounded Context

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vladikk doit-intl.com #DDDEU Strength:   Model M=S^D IN DOMAIN-DRIVEN DESIGN Distance Bounded Context

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vladikk doit-intl.com #DDDEU Strength:   Functional M=S^D IN DOMAIN-DRIVEN DESIGN Distance Aggregate

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vladikk doit-intl.com #DDDEU Implementation   Strength M=S^D IN DOMAIN-DRIVEN DESIGN Distance public class CampaignPublishingSaga { private readonly ICampaignRepository _repository; private readonly IList _events; // ... public void Process(CampaignActivated activated) { var campaign = _repository.Load(activated.CampaignId); var advertisingMaterials = campaign.GenerateAdvertisingMaterials); var commandIssuedEvent = new CommandIssuedEvent( target: Target.PublishingService, command: new SubmitAdvertisementCommand(activated.CampaignId, advertisingMaterials)); _events.Append(activated); _events.Append(commandIssuedEvent); } public void Process(PublishingConfirmed confirmed) { var commandIssuedEvent = new CommandIssuedEvent( target: Target.CampaignAggregate, command: new TrackConfirmation(confirmed.CampaignId, confirmed.ConfirmationId)); _events.Append(confirmed); _events.Append(commandIssuedEvent); } public void Process(PublishingRejected rejected) { var commandIssuedEvent = new CommandIssuedEvent( target: Target.CampaignAggregate, command: new TrackRejection(rejected.CampaignId, rejected.RejectionReason)); _events.Append(rejected); _events.Append(commandIssuedEvent); } }

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vladikk doit-intl.com #DDDEU M=S^D IN DOMAIN-DRIVEN DESIGN public class CampaignPublishingSaga { private readonly ICampaignRepository _repository; private readonly IList _events; // ... public void Process(CampaignActivated activated) { var campaign = _repository.Load(activated.CampaignId); var advertisingMaterials = campaign.GenerateAdvertisingMaterials); var commandIssuedEvent = new CommandIssuedEvent( target: Target.PublishingService, command: new SubmitAdvertisementCommand(activated.CampaignId, advertisingMaterials)); _events.Append(activated); _events.Append(commandIssuedEvent); } public void Process(PublishingConfirmed confirmed) { var commandIssuedEvent = new CommandIssuedEvent( target: Target.CampaignAggregate, command: new TrackConfirmation(confirmed.CampaignId, confirmed.ConfirmationId)); _events.Append(confirmed); _events.Append(commandIssuedEvent); } public void Process(PublishingRejected rejected) { var commandIssuedEvent = new CommandIssuedEvent( target: Target.CampaignAggregate, command: new TrackRejection(rejected.CampaignId, rejected.RejectionReason)); _events.Append(rejected); _events.Append(commandIssuedEvent); } } Bounded Context Bounded Context Bounded Context Aggregate

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vladikk doit-intl.com #DDDEU Implementation Functional Model Contract INTEGRATION STRENGTH

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vladikk doit-intl.com #DDDEU M = S ^ D

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vladikk doit-intl.com #DDDEU “The most e ff ective tool available for dealing with complexity is abstraction. Many types of abstraction can be used, but encapsulation is the main form of abstraction by which complexity is managed in object-oriented programming.” - Rebecca Wirfs-Brock

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vladikk doit-intl.com #DDDEU WRAP UP

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vladikk doit-intl.com #DDDEU KNOWLEDGE: THE ENERGY OF SOFTWARE DESIGN So ft ware systems are sustained by the transport of knowledge (energy) through hierarchical networks of modules.

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vladikk doit-intl.com #DDDEU Knowledge (sublinear growth) Complexity (superlinear growth) Cognitive Limit (No growth) Functionality (Linear growth)