Microservices Architecture (MSA)

Microservices architecture structures an application as a set of small, independently deployable services, each owning its own data and communicating over APIs or events. It enables independent scaling and release at the cost of distributed-systems complexity.

Common patterns include API gateway, service discovery, circuit breaker, saga, CQRS and event sourcing, database per service and the strangler fig for migration. The MSA Patterns page covers them.

They solve different problems. An API gateway manages north-south traffic from clients into the system, while a service mesh manages east-west traffic between services, with security, retries and observability.

Event-driven microservices communicate asynchronously through events and brokers, which reduces coupling and improves resilience. Many microservice systems combine synchronous APIs with asynchronous events.

Both organize functionality as services. SOA typically shares services across the enterprise, often through an ESB, while microservices favor small, autonomous services with decentralized governance and data.