There are different interpretations of what microservices means and how it relates to service-oriented architecture (SOA). In this section, we are going to view microservices as a refinement of SOA and not a new architectural pattern. The microservice architecture extends SOA by adding some additional key principles which require that services must:

• be small - hence the term micro
• be built around a business capability
• be loosely coupled with other services
• be independently maintainable
• have an isolated state