API Composition
ELI5 — The Vibe Check
API composition is when one service calls several other services and smooshes the results together into one response. The client asks for a 'user profile page' and the composer calls the user service, the order service, and the reviews service, then combines everything.
Real Talk
A pattern where a composer service aggregates data from multiple microservices to fulfill a query that spans multiple bounded contexts. The composer invokes individual services, collects their responses, and combines them into a unified response for the client. Common in microservices architectures as an alternative to database joins across services.
When You'll Hear This
"The API composition layer calls three services in parallel and merges the results." / "API composition is the microservices answer to cross-service joins — but watch out for latency."
Related Terms
API Gateway
An API Gateway is the front door for all your APIs.
Backends for Frontends (BFF)
BFF (Backends for Frontends) means each frontend gets its own custom backend. The mobile app gets a backend optimized for small payloads.
GraphQL
GraphQL is like ordering food where YOU specify exactly what you want on your plate.
Microservice
Microservices is an architecture where instead of one big app, you have many tiny apps that each do one thing.