APIs & Service Communication: REST, GraphQL, gRPC & Beyond
Master every major API paradigm — REST semantics and idempotency, GraphQL resolver trees and the N+1 problem, gRPC with Protocol Buffers, real-time channels (WebSockets, SSE, Webhooks), message queues, retry strategies with exponential back-off, and circuit-breaker fault isolation.
See the Invisible
Interactive simulators visualise what's hidden from view.
Hands-On Labs
Step through executions tick by tick. Manipulate state.
Why, Not Just What
Understand the reasoning behind every design decision.
Quizzes & Cheatsheets
Verify your understanding and keep a quick reference handy.
Get Certified
Earn a shareable certificate to prove your deep expertise.
Become the Engineer Who Supervises AI
As AI generates more code, understanding what that code does becomes more valuable, not less. Someone must verify AI output, debug failures, and make architectural decisions.
Build Your Architectural EdgeMost Production Incidents Start Between Two Services
Making API calls is the easy part. Knowing why they fail, how failures cascade across services, and which communication pattern fits each boundary is what keeps systems running in production.
You Know the Syntax. The Failures Still Surprise You.
You've watched a slow downstream service cascade into a full outage because nothing in your stack failed fast. You've copy-pasted retry logic without knowing why synchronized retries create thundering herds. You've picked REST, GraphQL, or gRPC based on team familiarity instead of mechanical tradeoffs. The API call itself is never the hard part. What happens after you hit send is where production breaks.
See the Invisible Mechanics
Every lesson includes an interactive simulator that makes network-level behavior visible and explorable.
Watch Data Cross the Wire
See data structures serialize into byte streams, cross the network boundary, and reassemble at the destination.
Trigger Cascading Failures Safely
Break circuit breakers, exhaust connections, and watch retry storms form without risking your production systems.
Trace Resolver Execution Paths
Step through GraphQL resolver trees to see exactly where and why N+1 queries multiply your backend calls.
What this course covers
8 lessons across API protocols, real-time patterns, async messaging, and distributed failure handling.
Network Boundary & Serialization
Trace data from function call to byte stream and back, and account for the real costs of network transit.
REST Semantics & Concurrency
Apply idempotency rules across HTTP methods, distinguish PUT from PATCH, and handle race conditions with ETag-based optimistic locking.
Schema-Driven Protocols
Diagnose N+1 problems in GraphQL resolver trees and use Protocol Buffers over HTTP/2 for typed, streaming service contracts.
Real-Time & Async Patterns
Implement WebSockets, SSE, and webhook delivery for live data, then decouple services with message queues and event logs.
Resilience & Failure Domains
Prevent cascading failures with exponential backoff, randomized jitter, and circuit breaker state machines that isolate failure domains.
Course Curriculum
8 lessons. Each with theory, interactive simulation, and quiz.
The Network Boundary: Serialization and RPC
The difference between local memory pointer dereferencing and remote procedure calls. How data structures are marshalled into byte streams for network transit, and why the network boundary introduces latency amplification and the fallacies of distributed computing.
REST Semantics and Idempotency
The strict definition of idempotency and safety across HTTP methods. How PUT (complete resource replacement) differs from PATCH (partial application), and how to handle concurrent data modifications with optimistic locking via ETag evaluation.
GraphQL Mechanics and the N+1 Problem
How schema-driven resolver trees execute, translating nested query structures into sequential backend data fetches. The mechanical cause of the N+1 query problem during list resolution, and the Dataloader pattern for batching and per-request memoization.
gRPC and Protocol Buffers
Strongly-typed binary contracts using Protocol Buffers with field numbering and varint encoding. How HTTP/2 persistent streams support unary requests, server-side streaming, client-side streaming, and full bidirectional multiplexing.
WebSockets, SSE, and Webhooks
The HTTP Upgrade mechanism for establishing full-duplex WebSocket connections with opcode-based frame routing. Server-Sent Events over a persistent unidirectional HTTP connection. Webhook delivery as HTTP POST callbacks, including HMAC payload signing, retry policies, and idempotency key handling.
Message Queues and Asynchronous Decoupling
The transition from synchronous HTTP RPC to broker-mediated async communication. Visibility timeouts, explicit consumer acknowledgments (ACK/NACK), requeuing behaviors, and the structural difference between point-to-point task queues and persistent partitioned event logs.
Failure Domains: Retries, Backoff, and Jitter
Handling transient network timeouts with exponential backoff. The thundering herd problem during synchronized reconnections, and how randomized jitter disperses retry clusters to protect backend stability.
Cascading Failures and Circuit Breakers
How downstream service latency causes upstream thread and socket exhaustion. The Circuit Breaker state machine transitions: Closed (normal execution), Open (failing fast to prevent overload), and Half-Open (probing downstream recovery). Error threshold calculations and isolation of failure domains.
Ship Services That Communicate Reliably
After this course, you'll choose between REST, GraphQL, gRPC, WebSockets, and message queues based on real mechanical tradeoffs. You'll implement retry strategies, circuit breakers, and async patterns that prevent the cascading failures you used to debug after the fact.
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