Composable services refer to a software architectural pattern that emphasizes the construction and integration of modular, independent services to build complex applications or systems. With this approach, services are designed to be self-contained, loosely coupled, and independently deployable components that expose well-defined interfaces.
That sounds a lot like microservices … but it is also much more. Where microservices focus on structuring applications as groups of stand-alone services, composable architecture puts more emphasis on making those services reusable and manageable components.
Many of the issues and problems that have plagued the development and use of microservices can be blamed upon a failure to pay sufficient attention to microservice composability — not upon the microservices pattern itself.
The composable service pattern is based upon composing applications from self-contained, reusable services — each service focused on a specific functional or business capability so that it can be developed, deployed, and scaled independently.
These services communicate with each other through well-defined request or event messages, enabling them to work together seamlessly within or across processes.