September 12th, 2015
(written by lawrence krubner, however indented passages are often quotes). You can contact lawrence at: firstname.lastname@example.org
In short, maximize future freedom of action. This heuristic also answers the when and why questions for microservices.
To prove it, let’s start with Sprott & Wilkes on SOA. Wait, Service Oriented Architecture? SOA is microservices loving parent. The philosophy trickles down:
When the service is abstracted from the implementation it is possible to consider various alternative options for delivery and collaboration models. […] It is entirely realistic to assume that certain services will be acquired from external sources because it is more appropriate to acquire them. For example authentication services, a good example of third party commodity services that can deliver a superior service because of specialization, and the benefits of using a trusted external agency to improve authentication.
In other words, service orientation maximizes future freedom of action.