Microservices are autonomous

Microservices are self-contained, independently deployable, and autonomous services that take full responsibility of a business capability and its execution. They bundle all dependencies including the library dependencies; execution environments, such as web servers and containers; or virtual machines that abstract the physical resources.

One of the major differences between microservices and SOA is in its level of autonomy. While most of the SOA implementations provide the service-level abstraction, microservices go further and abstract the realization and the execution environment.

In traditional application developments, we build a war or a ear, then deploy it into a JEE application server, such as JBoss, Weblogic, WebSphere, and more. We may deploy multiple applications into the same JEE container. In the microservices approach, each microservice will be built as a fat jar embedding all dependencies and run as a standalone Java process:

Microservices may also get their own containers for execution, as shown in the preceding diagram. Containers are portable, independently manageable, and lightweight runtime environments. Container technologies, such as Docker, are an ideal choice for microservices deployments.