Lesson 126
APIs: REST, GraphQL & gRPC
Contracts between programs
1:00How programs talk to each other — comparing REST resources and verbs, GraphQL client-driven queries, and gRPC binary streaming, plus the cross-cutting concerns every API must handle.
By the end, you can
- Explain what an API contract is and why it decouples caller from implementation.
- State what each HTTP verb does and identify which are idempotent.
- Describe REST statelessness and explain why it aids horizontal scaling.
- Define over-fetching and under-fetching and explain how GraphQL eliminates both.
- Read a basic GraphQL query and identify which operation type (query/mutation/subscription) it uses.
- Explain why gRPC is faster than REST for internal microservices and name its four call shapes.
- Match each cross-cutting concern (auth, rate limiting, pagination, webhooks) to its mechanism.
- Choose the right API style — REST, GraphQL, or gRPC — for a given use case.
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