domain driven design in c#3.0

DDD with C# 3.0 features: Solar

System SimulationAndre Boonzaaijer, Pieter-Joost van de Sande

{aboonzaaijer, pjvdsande}@sogyo.nl

http://born2code.net | http://whiletrue.nl | http://sogyo.nl

Today’s agenda

• DDD – short intro• Case: Problem definition• Case: C# (2.0) solution• Case: C# 3.0 extensions• Demo

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What is “Domain Driven”?

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It’s not: Layering

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Presentation Layer

Data Layer

Layering

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Presentation Layer

Data Layer

Business logic

Layering

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Presentation Layer

Data Layer

Business logic

Layering

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Presentation Layer

Data Layer

Business logic

Layering

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Presentation Layer

Data Layer

Business logic

+/- 2 years

Layering

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Presentation Layer

Data Layer

Business logic

+/- 2 years

+/- 5 years

Layering

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Presentation Layer

Data Layer

Business logic

+/- 2 years

+/- 5 years

?

Layering

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Presentation Layer

Data Layer

Business logic Email

SMS

Printing

Email

Where?

Layering

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Presentation Layer

Data Layer

Business logic

Sunflower

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Case…

• Build a runnable solar system simulator– 1 star in the centre– Configurable amount of planets (mass is max

1% of the star’s mass)– Laws of physics:

• F = M * a• Fg = M1*M2 / d^2

– Starting point: Random generated• Draft a domain model.

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Gravity

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(x,y)

force = 0;Foreach body in universe force += body.getForce(x,y);

body.move(force);

Domain

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Wrapping the domain

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UserInterface

Clock

Database

Bootstrapper / Host

User Interface

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Clock

• Standard implementation• Configurable interval• Start(), Stop(), Tick event

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Database

• O/R bridging– Table per domain class– Column for public properties (discussion)– Associations converted to foreign keys

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?

Bootstrap• Instantiation (create form, clock and universe

components)

• Event subscription

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Domain in C# 3.0

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Domain in C# 3.0

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Universe class Methods

• TimerPassed() method - ‘Classic’

- Lambda:

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Universe class Methods

• GetPlanetsInRange() Method

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Universe class Methods

• GetPlanetsInRange() Method: Lambda

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Universe class Methods

• GetPlanetsInRange() Method: LINQ

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Form1 class Methods

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DrawUniverse: Who is responsible?UI.DrawUniverse() vs

Universe.Draw()

Universe.Draw() Extension

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Universe.Draw() Extension

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Extension Methods: How

• Add a Static class to your namespace• Add static methods for each extension• Add a ‘this’ parameter to the ext. method

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Refences

• DDD Masterclass (http://domaindrivendesign.nl)• Rebecca Wirfs-Brock: Object Design• Eric Evans: Domain Driven Design

• Blogs– http://born2code.net– http://whiletrue.nl– http://software-innovators.nl

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