Advanced Application Architecture Symfony Live Berlin 2018
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This document discusses advanced application architecture, specifically layers, ports, and adapters. It introduces layered architecture as a way to define coupling and cohesion in a codebase. The layers separate domains into infrastructure, application, and domain layers with dependencies only allowed in one direction from higher to lower layers. Ports define interfaces that layers can depend on while adapters implement ports, allowing for decoupling and replacement of components. The document also discusses testing at the unit, integration, acceptance, and system levels to verify the architecture.
Advanced Application Architecture Symfony Live Berlin 2018
- 1. ADVANCED APPLICATION ARCHITECTURE I - Layers Matthias Noback @matthiasnoback
- 3. matthiasnoback/ layers-ports-and-adapters- workshop Clone from GitHub docker-compose pull bin/composer.sh install docker-compose up -d
- 4. DEMO TIME Navigate to localhost (or localhost:8080)
- 5. ARCHITECTURE Decisions about coupling and cohesion
- 6. COUPLING How are things linked to each other?
- 7. COHESION Which things belong together?
- 8. LAYERED ARCHITECTURE An answer to both questions
- 9. LAYERS Help you protect what's in a deeper layer
- 10. LAYERS Allow you to define dependency rules
- 11. LAYERS Define the right place to put things
- 13. TRADITIONAL LAYERING Works well with JS view model data
- 14. LAYERS Horizontal division (as opposed to...)
- 16. COHESION A basic set of layers infrastructure application domain
- 17. COUPLING The dependency rule Layers should only depend on deeper layers
- 19. COUPLING Dependency inversion principle Classes should always depend on things that are more abstract
- 20. COUPLING Dependency inversion principle low-levelconcrete class specific abstract interface generic high-level
- 22. COUPLING Dependency inversion principle use implement
- 23. COUPLING Is about dependencies in code Use Dependency Injection
- 24. LAYER CONVENTIONS Domain layer Domain model: ➤ Entities ➤ Value objects ➤ Domain services ➤ Factories Business logic Decisions Data State Behavior
- 25. LAYER CONVENTIONS Application layer ➤ Find an object ➤ Change something ➤ Notify something ➤ Get some information Use cases Orchestration
- 26. LAYER CONVENTIONS Infrastructure layer Communication with: ➤ HTTP client ➤ Database ➤ Filesystem ➤ Email server ➤ Message broker Connecting the application to the world outside
- 27. MATTHIASNOBACK/LAYERS- PORTS-AND-ADAPTERS- WORKSHOP Assignments are on GitHub in assignments/ php -S 0.0.0.0:8080 -t public/
- 29. ADVANCED APPLICATION ARCHITECTURE II - Ports & adapters
- 30. MESSAGING ... is the big idea
- 31. PORTS (COHESION) Web, CLI, test client, messages, database queries User interface Persistence
- 33. HEXAGONAL ARCHITECTURE Same thing! User interface Persistence
- 34. PORTS... AND ADAPTERS (De)serialization, translation, structural validation HTTP SQL
- 36. PORT ADAPTERS ...in the Infrastructure layer
- 37. APPLICATION SERVICES ... in the Application layer
- 38. DOMAIN MODEL in the Domain layer
- 41. APPLICATION SERVICES Most often they are "command handlers" Command object is a DTO Represents a user's intention Contains primitive-type values
- 42. APPLICATION SERVICES Translate, and orchestrate From primitive-type values to rich domain objects Manipulates an entity Persists it May dispatch events
- 43. VALIDATION At different levels Structural validation of messages User-friendly input validation Domain invariant protection
- 44. STRUCTURAL VALIDATION Infrastructure layer Form keys JSON schema
- 45. USER-FRIENDLY INPUT VALIDATION Infrastructure layer Usability concern Prevent problems later on Localized, translated Friendly
- 46. DOMAIN INVARIANT PROTECTION Application & Domain layer Domain objects: always valid Valid state Valid state transitions
- 50. INCOMPLETE ENTITY A Meetup without an ID...
- 51. DATABASE-GENERATED ID Faux-auto increment (check out the code)
- 52. ALTERNATIVE: UUID Universally Unique Identifier 7d7fd0b2-0cb5-42ac-b697-3f7bfce24df9
- 53. assignment/06.md A hidden dependency on the persistence mechanism
- 54. ALTERNATIVE: SEQUENCE MeetupId encapsulates the type of ID used
- 55. ADVANTAGES OF USING LAYERS, PORTS & ADAPTERS Offers insight into the application Provides a useful convention for the team Isolates the low-level details Allows for alternative implementations Helps with testing
- 57. UNIT TESTS Testing your units of code One class at a time No IO No setup required Mocking only dependencies "you own"
- 58. INTEGRATION TESTS Testing your adapters Maybe multiple classes Including IO Some setup required Mocking no dependencies
- 59. ACCEPTANCE TESTS Testing your application services Multiple classes Use cases Infrastructure stand-ins
- 60. SYSTEM TESTS Testing your application end-to-end The real deal
- 61. TESTING PYRAMID Make it well-balanced Unit Integration System Acceptance Development Regression
- 62. TESTING PYRAMID Make it well-balanced Supports development Prevents regressionSlow, brittle Fast, stable Proof of effectiveness Proof of Correctness
- 63. assignment/07.md Different types of tests
- 64. ACCEPTANCE TESTS Use infrastructure stand-ins Acceptance test test the application layer
- 67. assignment/08.md A test double for the Persistence port
- 68. assignment/09.md An acceptance test for the application layer
- 69. A WELL-BALANCED TEST SUITE Adapters can be easily replaced Test suite is fast Feedback is quick Small amount of fragile tests Enables continuous delivery