Deciphering Glyph :: Bilithification
Several years ago at O’Reilly’s Software Architecture conference, within a comprehensive talk on refactoring “Technical Debt: A Masterclass”, r0ml1 presented a concept that I think should be highlighted.
If you have access to O’Reilly Safari, I think the video is available there, or you can get the slides here. It’s well worth watching in its own right. The talk contains a lot of hard-won wisdom from a decades-long career, but in slides 75-87, he articulates a concept that I believe resolves the perennial pendulum-swing between microservices and monoliths that we see in the Software as a Service world.
Microservices are often adopted by small teams due to their advertised benefits. Advocates from very large organizations—ones that have been very successful with microservices—frequently give talks claiming that microservices are more modular, more scalable, and more fault-tolerant than their monolithic progenitors. But these teams rarely appreciate the costs, particularly the costs for smaller orgs. Specifically, there is a fixed operational marginal cost to each new service, and a fairly large fixed operational overhead to the infrastructure for an organization deploying microservices in at all.
With a large enough team, the operational cost is easy to absorb. As the overhead is fixed, it trends towards zero as your total team size and system complexity trend towards infinity. Also, in very large teams, the enforced isolation of components in separate services reduces complexity. It does so specifically intentionally causing the software architecture to mirror the organizational structure of the team that deploys it. This — at the cost of increased operational overhead and decreased efficiency — allows independent parts of the organization to make progress independently, without blocking on each other. Therefore, in smaller teams, as you’re building, you should bias towards building a monolith until the complexity costs of the monolith become apparent. Then you should build the infrastructure to switch to microservices.
