Gateway Middlewares
In software engineering, gateway middleware refers to middleware components that act as an entry point (or "gateway") between clients and backend services, managing and controlling communication.
They sit at the boundary of a system (like an API gateway or edge gateway) and handle cross-cutting concerns so that backend services don’t have to.
Functions of Gateway Middleware
- Request routing → Direct requests to the correct service.
- Load balancing → Distribute traffic across multiple service instances.
- Authentication & authorization → Check credentials, enforce access control.
- Protocol translation → Convert between protocols (e.g., HTTP to gRPC, REST to SOAP).
- Rate limiting & throttling → Prevent abuse and ensure fair resource usage.
- Caching → Improve performance by serving responses from cache.
- Logging, monitoring, tracing → Enable observability of requests.
Types of Gateway Middleware
API Gateway Middleware
- Manages REST/GraphQL/gRPC API requests from external clients.
- Examples: Kong, Apigee, Tyk, AWS API Gateway, NGINX (as gateway).
Service Gateway Middleware (inside microservice architectures)
- Sometimes overlaps with service mesh ingress/egress.
- Examples: Istio ingress gateway, Envoy proxy, Traefik.
Note: This is particularly useful with containers, where rapid changes in IPs occur, and these service meshes can act as a name lookup for the required services.
Edge Gateway Middleware
- Sits at the "edge" of a network/data center and manages traffic in/out.
- Examples: Cloudflare edge workers, NGINX edge gateway, HAProxy.