I et system kommunikerer komponenter (services, klienter) gennem APIs og forskellige protokoller — synkrone (REST, gRPC) og asynkrone (messaging/queues). At forstå, hvordan komponenter kommunikerer, er grundlæggende for at designe systemer, der består af flere dele.
Synkron kommunikation (request/response)
The caller WAITS for a response (blocking):
REST (HTTP) → most common; resources over HTTP (JSON) → simple, ubiquitous, web-friendly
gRPC → high-performance RPC (binary, HTTP/2) → fast, typed; good for internal services
GraphQL → flexible queries (client requests exactly what it needs)
→ for: direct request/response where the caller needs an answer now
