Modernizing Monoliths: Principles, Patterns, Risks and Roadmaps

The legacy monolith (AKA Big Ball of Mud) is a challenge to startups and even more to large and established companies, built when paradigms and tooling followed different patterns. As the tech ecosystem has evolved, new patterns, tools, APIs and possibilities tend to overtake them, tightly coupled apps become a source of increasing technical debt and diminishing competitiveness and business value. But the alternatives are fraught with risks, challenges and complications. I will review 6 state-of-the-art patterns: maintaining the legacy (Wikipedia); decomposing into a modular monolith (Etsy); decomposing into microservices (About You); Serverless monoliths (Phantom); Serverless microservices (Liberty Mutual), and microservices as a service (Moonpig/CommerceTools). In the process I will offer principles, roadmaps, risks and tools to make the jump, touching on the issue of language migration/complementation.