97 Things Every Java Programmer Should Know

Chapter 84. Trade-Offs in a Microservices Architecture

Kenny Bastani

Is there an optimal software architecture?  What does it look like? How do we measure “optimal” when it comes to building and operating software? An optimal software architecture is one that has maximal flexibility for change at the lowest possible cost. Here, cost is measured in terms of certain qualities that represent a software architecture’s design and implementation—in addition to the cost of the infrastructure to operate it. The defining trait of a software quality is that it can be tangibly measured and has an impact on other qualities.

For example, if a software architecture requires strong consistency guarantees, there is an impact on qualities like performance and availability. Eric Brewer created the CAP theorem to describe a set of measurable trade-offs where you can only choose two out of three guarantees for running a database: consistency, availability, and partition tolerance. The theorem states that when applications share state across the boundaries of a network, you must choose between consistency or availability, but you cannot have both.

One of the main problems with microservices is that there is no single comprehensive definition. Moreover, microservices are a collection of concepts and ideas that are based on a set of constraints for delivering a services architecture. A microservice, ...