php[world] 2017 Domain-Driven Design Workshop

Transcript

1. Domain-Driven Design Deconstructed Domain-Driven Design Deconstructed Andrew Cassell @alc277 andrewcassell.com
8. Domain-Driven Design
9. Domain-Driven Design
11. Common Sense Software Development
20. 20
22. Encapsulation & Immutability & Modeling & Behavior
23. Domain
24. Domain
25. BEER
30. Photo: Kathleen Pierce - Bangor Daily News
42. Brewing Software
54. recipe hop grain hop_inventory grain_inventory recipe_hop_link user recipe_user_link brew_event ROLE_USER ROLE_ADMIN
55. Source: http://jonclaytonbiz.com/
58. People don't want to buy a quarter-inch drill, they want a quarter-inch hole. Theodore Levitt
62. #JBTD (http://jobstobedone.org/)
64. YYYYY
65. Why? Why? Why? Why? Why?
66. Search Caluclation List Automation
67. DDD !=
73. http://www.csharpstar.com/
75. DDD CRUD Correctness Testability Usability Maintainability Modifiability
77. DDD BALL OF MUD / CRUD Correctness Testability Usability Maintainability Modifiability
78. DDD CRUD/MUD Recipe Building Inventory Brewhouse Activity Beer Menu / Prices Brew Sessions Brewery Website Calclations QA Record Keeping
79. Who is responsible
84. Ubiquitous Language
85. Ubiquitous Language Developers Domain Experts
86. Ubiquitous Language
87. User Brewer Employee Taster Customer
89. 1. Naming Things 2. Cache Invalidation 3. Off By One Errors Top 10 Reasons Programming is Hard
90. $recipe = BeerRecipe::findOrFail($uuid);
 $hop = HopRepo::where(“name”,”=“,”Simcoe”)->take(1)->get(); 
 if (!$recipe->hopsArray()->contains(‘hop_id’,$hop->id)) {
 
 $recipe->hopsArray()->attach($hop->id, [‘weight' => 1.0]);
 }
 
 
 $recipe->save();
92. Ubiquitous Language $recipe->addGrains($grains); Code: We need to be able to add a measured amount of grain to a recipe. Business:
93. Ubiquitous Language $recipe->getEstimatedAlcoholByVolumeABV(); Code: We need to be able to calculate an estimated ABV for a recipe. Business:
94. Ubiquitous Language $storage = (new StorageFacilities())->findByOneName(“Silo #4”); $storage->howMuchOfGrainType(new GrainType(‘Winter Wheat’)); Business: Code: We need to know how much Winter Wheat is in our storage silo #4.
95. Ubiquitous Language $recipe->addDryHop($hopQuantity,$schedule); Code: We need to add .2oz of 12% AA per gallon of Simcoe hops to a recipe 7 days after the boil is complete. This is called dry hopping. $schedule = new DryHopSchedule(‘7 Days’); $hopQuantity = HopQuantity::(“Simcoe”,”12%AA”,”.2oz per gallon”); Business:
96. @recipe Feature: A user should be able to dry hop a recipe Scenario: User adds dry hops to recipe Given I am authenticated as a user And I am on “/recipe/0ef360fd“ And I press "Add Hops” And I fill out form with: | Hop Name | | Simcoe | Then I see “Alpha Acid: 11.5 - 15.0“
97. $recipe->dryHop($hop); $recipe->addIngredient($hop); $recipe->addToBoil($hop); $recipe->addToBoilKettle($hop); $recipe->addToBoiler($hop); $recipe->addFirstWortHop($hop); $recipe->addToFermenter($hop); $recipe->addToMashTun($hop); //fails
98. $hop = (new HopsSupply(…))->findOneByName(‘Simcoe’); $catalog = new RecipeCatalog(…); $recipe = $catalog->findOneRecipeByName(‘iPHPA’); $recipe->addDryHop($hop, new DryHopSchedule(‘7 Days’)); $brewers = new Brewers(…); $brewer = $brewers->findOneByUsername(‘cassell’); $brewSession = $brewer->brew($recipe); $brewSession->dryHopsWereAdded($hop, Datetime::now());
99. $hop = (new HopsSupplyRepo())->findOneByName(‘Simcoe’); $catalog = new RecipeCatalogRepository(…); $recipe = $catalog->findOneRecipeByName(‘iPHPA’); $recipe->addDryHop($hop, new DryHopSchedule(‘7 Days’)); $brewers = new BrewersRepository(…); $brewer = $brewers->findOneByUsername(‘cassell’); $brewSession = $brewer->brew($recipe); $brewSession->dryHopsWereAdded($hop, Datetime::now());
100. CRUD/MUD DDD Users Brewers String RecipeName Integer IBU Float(7,3) AlphaAcid Array of ORM Objects GrainBill BeerInventoryRepositoryInterface Menu
104. $hop = (new HopsSupply())->findOneByName(‘Centennial Pellets’); $catalog = new RecipeCatalog(…); $recipe = $catalog->findOneRecipeByName(‘iPHPA’); $recipe->addDryHop($hop, new DryHopSchedule(‘7 Days’)); $brewers = new Brewers(…); $brewer = $brewers->findOneByUsername(‘cassell’); $brewSession = $brewer->brew($recipe); $brewSession->dryHopsWereAdded($hop, Datetime::now());
105. […], we want to establish the idea that a computer language is not just a way of getting a computer to perform operations but rather that it is a novel formal medium for expressing ideas about methodology. Thus, programs must be written for people to read, and only incidentally for machines to execute.
106. DDD BALL OF MUD/CRUD Correctness ✓ Testability Usability Maintainability Modifiability
108. The Brewer, designed and engraved in the Sixteenth Century, by Jost Amman.
109. Inventory Marketing Finance Production “Hop”
110. Quantity at a Location Flavor Expenditure Ingredient “Hop”
111. Bounded Contexts
112. Inventory Recipes Brewhouse
113. Slide: Vaughn Vernon
115. Inventory Recipes Brewhouse
116. Inventory Recipes Brewhouse
117. Message Inventory Recipes Brewhouse
118. Domain Event Inventory Recipes Brewhouse
124. Personas
125. adaptivepath.com
126. Photos: Terry Brown and Gordon Stettinius Alice Shane P.J. Sam George Male Age 32 Brewer for 3 Years Got into brewing after the record store he worked at closed. Is very tech savvy and carries an Android. Male Age 50 Brewing for 10 Years Just Promoted to COO Retired civil servant who believes software can make a brewery for regulatory compliant. Female Age 27 New Hire Library science graduate who was just hired away from the local university. iPhone user. Male Age 52 Librarian for 30 years Has been brewing beer as long as he can remember. Loves beer podcasts but is not a fan of technology. Male Age 46 Brewer for 20 Years Loves poetry and writing. Brewing is just a job to pay the bills.
131. https://blog.intercom.io/using-job-stories-design-features-ui-ux/
134. 7 Dirty Words When Meeting With a Domain Expert 1.Session 2.Repository 3.Abstract 4.Interface 5.Class 6.Database 7.Foreign Key
135. User Research
136. Photo: Mathias Verraes
137. Command Actor Model Domain Event
138. Domain Event • Something that happens in the software. • Past Tense
139. Domain Event • Beer Was Brewed • Grain Was Added • Hops Were Added • Brewer Changed Email Address
149. Command Actor Model Domain Event
150. Command • The action that precipitates the event • Written in Present Tense
151. Command • Start Brewing Session • Add Grain to Recipe • Add Hops To Fermenter • Change Email Address
154. Command Actor Model Domain Event
155. Model • Command is acted upon this thing • Might Include Supporting Models
156. Model • Recipe • Ingredient • Brewer
158. Command Actor Model Domain Event
159. Actor • Who did it? • If you only have one user you might not need this
162. Command Actor Model Domain Event
165. business origami
166. Jess McMullin Business Origami
167. Jess McMullin Business Origami
168. Jess McMullin Business Origami
169. Sean Jalleh
172. Source: Jeff Patton
178. DDD BALL OF MUD/CRUD Correctness ✓✓ Testability Usability ✓ Maintainability Modifiability
179. Domain Objects Value Objects Domain Events Entities Aggregates
180. Value Object Immutable No Identity (Only Values) Hop Name Amount Paid Temperature Entity Identifiable Mutable Lifecycle Contains Value Objects Line Item Brewer Water Chemistry Aggregate Entity Responsible For Child Entities Transaction Boundary Invoice Recipe Brew Session
181. Value Objects
182. Email Address Recipe Name Date We Brewed On Weight Temperature Value Objects
183. Value Objects Email Address Recipe Name Date We Brewed On Weight Temperature Ubiquitous Language
184. Value Objects EmailAddress RecipeName BrewedOn Pounds DegreesFahrenheit Email Address Recipe Name Date We Brewed On Weight Temperature
185. Not Just Static Typing https://github.com/Fiedzia/type-system-research/blob/master/README.md Value Objects
186. Immutable
187. Immutable Avoid Spooky Action at a Distance
188. ALWAYS VALID Value Objects
189. Value Objects
190. “Gateway Drug to Test Driven Development” Value Objects
191. “Gateway Drug to Test Driven Development” Value Objects #MYTESTSDONTPASS
192. Plain PHP Objects (POPOs) Value Objects
193. Plain PHP Objects (POPOs) • Declare Class Properties as Private • No Setters (behaviors will return new) • No References to Mutable Objects • Throw Exceptions in Constructor Value Objects
194. Only depend on scalars or other value objects. Value Objects
195. They are not dependencies that you inject. Value Objects
196. RecipeName Example
201. cassell:beeriously cassell$ docker run --rm --interactive --tty --network beeriously_default --volume `pwd`:/app --user : --workdir /app beeriously_php-fpm /app/vendor/bin/phpunit --configuration /app/src/Tests/Unit/ phpunit.xml.dist PHPUnit 6.4.3 by Sebastian Bergmann and contributors. FEE 3 / 3 (100%) Time: 2.34 seconds, Memory: 4.00MB There were 2 errors: 1) Beeriously\Tests\Unit\Domain\Recipe\RecipeNameTest::testGetter Error: Class 'Beeriously\Domain\Recipe\RecipeName' not found /app/src/Tests/Unit/Domain/Recipe/RecipeNameTest.php:20 2) Beeriously\Tests\Unit\Domain\Recipe\RecipeNameTest::testToString Error: Class 'Beeriously\Domain\Recipe\RecipeName' not found /app/src/Tests/Unit/Domain/Recipe/RecipeNameTest.php:26 -- There was 1 failure: 1) Beeriously\Tests\Unit\Domain\Recipe\RecipeNameTest::testEmptyFails Failed asserting that exception of type "Error" matches expected exception "Beeriously\Domain\Recipe\InvalidRecipeNameException". Message was: "Class 'Beeriously\Domain\Recipe\RecipeName' not found" at /app/src/Tests/Unit/Domain/Recipe/RecipeNameTest.php:15 . ERRORS! Tests: 3, Assertions: 1, Errors: 2, Failures: 1.
203. cassell:beeriously cassell$ docker run --rm --interactive --tty --network beeriously_default --volume `pwd`:/app --user : --workdir /app beeriously_php-fpm /app/ vendor/bin/phpunit --configuration /app/src/Tests/Unit/phpunit.xml.dist PHPUnit 6.4.3 by Sebastian Bergmann and contributors. .EE 3 / 3 (100%) Time: 1.56 seconds, Memory: 4.00MB There were 2 errors: 1) Beeriously\Tests\Unit\Domain\Recipe\RecipeNameTest::testGetter Error: Call to undefined method Beeriously\Domain\Recipe\RecipeName::getValue() /app/src/Tests/Unit/Domain/Recipe/RecipeNameTest.php:21 2) Beeriously\Tests\Unit\Domain\Recipe\RecipeNameTest::testToString Object of class Beeriously\Domain\Recipe\RecipeName could not be converted to string /app/src/Tests/Unit/Domain/Recipe/RecipeNameTest.php:27 ERRORS! Tests: 3, Assertions: 2, Errors: 2. cassell:beeriously cassell$
205. docker run --rm --interactive --tty --network beeriously_default --volume `pwd`:/app -- user : --workdir /app beeriously_php-fpm /app/vendor/bin/phpunit --configuration /app/ src/Tests/Unit/phpunit.xml.dist PHPUnit 6.4.3 by Sebastian Bergmann and contributors. ..E 2 / 3 (67%) Time: 292 ms, Memory: 4.00MB There was 1 error: 1) Beeriously\Tests\Unit\Domain\Recipe\RecipeNameTest::testToString Object of class Beeriously\Domain\Recipe\RecipeName could not be converted to string /app/src/Tests/Unit/Domain/Recipe/RecipeNameTest.php:27 ERRORS! Tests: 35, Assertions: 78, Errors: 1. make: *** [unit] Error 2 cassell:beeriously cassell$
207. cassell:beeriously cassell$ docker run --rm --interactive --tty --network beeriously_default --volume `pwd`:/app --user : --workdir /app beeriously_php-fpm /app/vendor/bin/phpunit --configuration /app/src/Tests/ Unit/phpunit.xml.dist PHPUnit 6.4.3 by Sebastian Bergmann and contributors. ... 3 / 3 (100%) Time: 192 ms, Memory: 4.00MB OK (3 tests, 4 assertions)
210. BrewedOn Example
214. Pounds Example
218. $poundA->reduceBy($poundB);
219. Eliminates Checking Value Objects
221. Factories $weight = $factory->create(‘2 lbs’);
222. Static Constructors
223. Natural Language Constructors
226. Temperature Example
232. Composite Value Objects
233. Full Name First Name + Last Name
235. Encoding Business Logic in Value Objects
236. Amount of Alcohol
238. ABV
239. Sugar + Yeast = Alcohol + CO2
240. Sugar + Yeast = Alcohol + CO 2 C H O ->2C H OH + 2CO 6 12 6 2 5 2
241. Sugar + Yeast = Alcohol + CO2
242. Sugar + Yeast = Alcohol + CO2
243. Sugar - Sugar = Alcohol START FINISH
244. Sugar - Sugar = Alcohol START FINISH Volume Volume
245. Specific Gravity
247. Hydrometer
249. learntomoonshine.com
250. Michael L. Hall - Zymurgy, Summer 1995, vol. 18, no. 2
270. DDD CRUD/MUD RecipeName String Temperature Float(7,3) DateBrewed DateTime Gravity Float(7,3) ABV Function + Validation?
271. DDD BALL OF MUD/CRUD Correctness ✓✓ Testability ✓ Usability ✓ Maintainability Modifiability
273. Entities
274. Identifiable Have State and are Mutable (Lifecycle) Never in an Invalid State Operate using Value Objects No Security or Permission Checks *(Ideally) Storage Agnostic Entities
275. DO AS MUCH AS YOU CAN IN VALUE OBJECTS!
276. Doctrine Mappings Doctrine Annotations Laravel Eloquent ORM “Storage Agnostic”
277. BEHAVIOR FIRST! STORAGE SECOND! “Storage Agnostic”
278. Single Entity Entities Regular Aggregate Contain Other Entities
279. Brewer Grain Hops BeerOnTap Entity Types Regular Aggregate Invoice Recipe BrewSession BeerMenu
280. Making an Entity: Brewer Identifiable ID (UUID) Mutable $brewer->changeUsername $brewer->changeName $brewer->changeEmail Never in an Invalid State __construct Operate Using Value Objects FullName, EmailAddress, …
282. SETTERS ARE BAD
287. Calling two setters in a row on the same object Missing a Concept?
288. Calling two methods in a row on the same object Missing a Concept?
289. Passing more than one parameter to a method Missing a Concept?
292. Doctrine
302. Bounded Contexts
303. Inventory Recipes Brewhouse
304. Inventory Recipes Brewhouse Recipe\Grain Inventory\Grain Brewing\BrewSession\Grain
305. Inventory Recipes Brewhouse
306. Inventory Recipes Brewhouse Brewers Supporting Bounded Context
307. • Entities • Manages Child Entities • Transactional Boundary • The Easiest Models to Identify Aggregates
308. Aggregates Recipe BrewSession BeerMenu
318. DDD BALL OF MUD/CRUD Correctness ✓✓ Testability ✓✓ Usability ✓ Maintainability ✓✓ Modifiability ✓
319. Task Based User Interface
323. DDD BALL OF MUD/CRUD Correctness ✓✓ Testability ✓✓ Usability ✓✓ Maintainability ✓✓ Modifiability ✓
325. Security
326. Domain (Business Logic) Application Services Controller Persistence Event/Command Bus Security Templates
327. Controller Domain Framework
332. Controller Domain Framework
333. Mathias Verraes - Decoupling the Model from the Framework at Laracon EU 2014 https://www.youtube.com/watch?v=QaIGN_cTcc8
334. Ruby Midwest 2011 - Keynote: Architecture the Lost Years by Robert Martin https://www.youtube.com/watch?v=WpkDN78P884
337. Domain (Business Logic) Application Services Controller Persistence Event/Command Bus Security Templates
338. DDD BALL OF MUD/CRUD Correctness ✓✓ Testability ✓✓ Usability ✓✓ Maintainability ✓✓✓ Modifiability ✓
339. Domain Events
340. Domain Events • Part of the Core Domain • Happened In The Past • Important Enough To Record (Persist) • Important Enough To Concern Other Bounded Contexts • Immutable Value Objects • Do Not Contain Entities or Other Mutable Objects • Can Be Created in an Entity
342. BrewSessionWasPlanned
343. BrewSessionWasPlanned
351. DDD BALL OF MUD/CRUD Correctness ✓✓ Testability ✓✓ Usability ✓✓ Maintainability ✓✓✓ Modifiability ✓✓
352. Business Rules in a Specification
356. DDD BALL OF MUD/CRUD Correctness ✓✓✓ Testability ✓✓ Usability ✓✓ Maintainability ✓✓✓ Modifiability ✓✓
358. Command Query Responsibility Segregation
359. CQRS
360. Write Read
361. Write Model Read Model(s)
362. Write Domain Model Read Model(s)
363. Controller Command Bus Handler Handler Handler
364. Controller Command Bus Handler Handler Handler Request
365. Controller Command Bus Handler Handler Handler Command
368. Controller Command Bus Handler Handler Handler Command
369. Controller Command Bus Handler Handler Handler Command
370. Controller Command Bus Handler Handler Handler Command
371. Controller Command Bus Handler Handler Handler Response
372. Controller Command Bus Handler Handler Handler Response
373. Controller Command Bus Handler Handler Handler Response
374. https://gnugat.github.io/ 2016/05/11/towards-cqrs- command-bus.html
381. Why Do CQRS?
382. Controller Domain Framework
383. Controller API (versions?) Console Commands
384. Event Sourcing
388. Event Sourcing • Object Properties are Not Persisted • Events Are Persisted to 
 Append Only Event Storage
389. • Avoids Data Mapping • Avoids Object-relational Impedance Mismatch • Reduces Database Table Counts (Related Tables) • Potentially Reduces Model Counts Event Sourcing
390. Slide: Microsoft
391. Libraries • https://github.com/broadway • https://github.com/prooph • https://github.com/szjani/predaddy
392. Recipe Example
393. Learning More
394. homebrewersassociation.org
397. DEV BOOK CLUB https://www.youtube.com/user/devbookclub
403. DDDinPHP Google Group http://DDDinPHP.org
404. Final Thoughts
411. Inventory Recipes Brewhouse
412. Inventory Recipes Brewhouse Legacy Context
415. https://joind.in/talk/ee152 DDD Topics Covered •Ubiquitous Language •Event Storming •Modelling •Value Objects •Entities •Aggregates •Hexagonal Architecture •CQRS •Event Sourcing