Design and Evolution of APIs in Microservice Architecture
- 1. Keep Your Contracts in Check: Design and Evolution of APIs in Microservice Architecture
- 2. About Me • .NET Developer at Lohika • 5+ years of commercial experience • 3+ years at Lohika • Participated in development of 4 microservice-based systems, from 3 to 20+ services each.
- 3. • Ways of interservice communication and how not to get lost with your options. • API First development and how it can save time in multi-team environment. • SwaggerHub as a single Point of truth for REST API • Best practices for gRPC contracts and how to deal with changes in them. • Kafka Schema Registry - contract coordinator for different messaging scenarios Agenda
- 4. Tourist Agency Application Happy Monolith Past SQL TripPlanningService CustomerService HotelBookingService CarRentalService
- 5. Bright Microservice Future SQL TripPlanningService CustomerService HotelBookingService CarRentalService SQL Mongo DB ????
- 6. Synchronicity • Synchronous protocol • Asynchronous protocol Number of receivers • Single receiver • Multiple receivers Communication types
- 7. Synchronous protocol ≠ Synchronous Communication Client Trip Planning Service Car Booking Service Customer Service HTTP Sync Request HTTP Sync Response HTTP Sync Request HTTP Sync Response HTTP Sync Request HTTP Sync Response Client Trip Planning Service Car Booking Service Customer Service HTTP Sync Request HTTP Polling HTTP Polling HTTP Sync Response HTTP Polling HTTP Sync Request HTTP Sync Response
- 8. Number of Receivers Single Receiver - Command • At Least Once delivery • Exactly Once processing • Order of execution is important • Producer expects to receive response Multiple Receivers - Event • Fire and Forget • Louse Coupling between producers and consumers Trip Planning Service Car Booking Service Book a car for specific dates Customer Service Car Booking Service Trip Planning Service Hotel Booking Service Customer Info Changed
- 9. Who Owns the Contract? Single Receiver - Command • The inbound queue identifier • The format of the processed command types Multiple Receivers - Event • The topic identifier • The format of all emitted events
- 10. Command Model Consumer Producer Business Logic Implements business Logic Triggers business logic Quantity Always one Often many Autonomy Can run on its own Fails if no consumer Consumer owns the contract
- 11. Event Model Consumer Producer Business Logic Implements business Logic Reports an event Quantity Usually many Only one Autonomy Subordinate to producer Can run on its own Producer owns the contract
- 13. Code First Team Gonzo - Customer Service Team Kermit – Car Rental Service Investigate Implement Test Investigate Implement Test
- 14. Contract First Team Gonzo - Customer Service Team Kermit – Car Rental Service Define API Contract Investigate Implement Investigate Implement Test Test Agree on API Contract
- 15. • Development teams does not block each other • Good and consistent communication between teams • Consistent API models • Separation of concerns • Reusability • Easy documentation Contract First
- 16. REST Contracts - OpenAPI API description format for REST APIs. An OpenAPI file allows you to describe your entire API, including: • Available endpoints (/users) and operations on each endpoint (GET /users, POST /users) • Operation parameters Input and output for each operation • Authentication methods • Contact information, license, terms of use and other information.
- 17. Demo Time
- 18. gRPC Contracts – Protocol Buffers ProtoBuf Definitions protoc Compiler .NET Go Kotlin gRPC Server gRPC Client 2. Compile 1. Define 3. Implement
- 19. Keeping ProtoBuf in Line Pick Style Guide • Google’s Style Guide • Uber’s Style Guide (V1/V2) Lint your ProtoBuf files & Check for Breaking Changes • Prototool • Buf Setup Mock Servers • GripMock
- 20. Messaging Contracts – Kafka Schema Registry
- 21. Compatibility Types Compatibility Type Changes Allowed Upgrade First BACKWARD - Delete Fields - Add optional fields Consumers FORWARD - Add fields - Delete optional fields Producers FULL - Add optional fields - Delete optional fields Any order NONE - Any changes Usually - custom migration logic
- 22. Useful Tools • Stoplight Studio - https://stoplight.io/studio/ • Spectral - https://stoplight.io/open-source/spectral/ • OpenAPI-diff -https://github.com/OpenAPITools/openapi-diff OpenAPI Tooling • SwaggerHub - https://swagger.io/tools/swaggerhub/ • SwaggerHub CLI - https://github.com/SmartBear/swaggerhub-cli SwaggerHub • Prototool - https://github.com/uber/prototool • GripMock - https://github.com/tokopedia/gripmock gRPC Tooling
- 23. Thank You!