API Gateway
Definition
An API Gateway is a management tool that sits between a client and a collection of backend services. It acts as a reverse proxy to accept all application programming interface (API) calls, aggregate the various services required to fulfill them, and return the appropriate result.
Why It Matters
In a microservices architecture, an API gateway provides a single, unified entry point for external clients. It can handle tasks like authentication, rate limiting, and request routing, so that the individual backend services don't have to.
Contextual Example
A mobile app makes a single request to an API Gateway to get user profile data. The gateway then makes multiple requests to the user service, order service, and review service to gather the data, combines it into a single response, and sends it back to the app.
Common Misunderstandings
- An API Gateway manages "north-south" traffic (from outside to inside the system). A service mesh manages "east-west" traffic (between services inside the system).
- All major cloud providers offer a managed API Gateway service (e.g., Amazon API Gateway, Azure API Management).