Traits

While there is no "official" definition of a microservice, we can settle upon certain characteristics, based on what was described in the previous section:

• It has its own lifecycle
• Consumed over a well defined API
• It can be independently scaled as required
• Simple enough to be easily understood
• Has its isolated and own persistence, if any; it will never access other microservice persistence
• Communicates with other services using their exposed API's in order to cross boundaries

As a result of this, and given that every component (service) in the system exposes its functionality through a well defined (and hopefully documented) API, then, every microservice:

• Can be implemented in the most appropriate language and framework for the work
• Can have its own internal rules; e.g. one core microservice might be formally verified in isolation
• Can evolve at its own pace, as long as the exposed API's honor the contract that its consumers expect