API Gateways and Service Composition

An API gateway is a reverse proxy that serves as a single entry point for client requests to a distributed microservices architecture. It handles cross-cutting concerns like routing, authentication, rate limiting, and request transformation, abstracting the complexity of multiple backend services behind a unified API. In .NET, YARP (Yet Another Reverse Proxy) is Microsoft's production-ready gateway framework that provides high-performance routing, service composition, and middleware extensibility without lock-in to proprietary solutions.

This series takes you from foundational API gateway concepts through advanced service composition patterns. You'll learn how to design gateway architectures, implement YARP-based routing and transformation, aggregate requests across microservices, enforce rate limiting and authentication policies, implement Backend-for-Frontend (BFF) patterns for different clients, configure load balancing and health monitoring, orchestrate complex workflows, and optimize gateway performance under load. Each tutorial builds on prior knowledge with runnable .NET code examples and production-ready patterns you can adapt immediately.

By the end of this series, you'll understand how to architect a scalable API gateway that decouples client concerns from backend service evolution, enables rapid microservice development, and centralizes security and operational policies. Whether you're building an internal microservices network or exposing public APIs, API gateway patterns are foundational to modern distributed system design.

Articles in this series​

Articles in this series