Although we were early advocates for microservices and have seen the pattern used successfully on myriad systems, we've also seen microservices misapplied and abused, often as the result of microservice envy. Rather than start a new system with a collection of separately deployed processes, it's often advisable to start with a well-factored monolith and only break out separately deployable units when the application reaches a scale where the benefits of microservices outweigh the additional complexity inherent in distributed systems. Recently we've seen a resurgence of interest in this approach and a more detailed definition of what, exactly, constitutes a well-factored monolith. Spring Modulith is a framework that helps you structure your code in a way that makes it easier to break out microservices when the time is right. It provides a way to modularize your code so that the logical concepts of domains and bounded context are aligned with the physical concepts of files and package structure. This alignment makes it easier to refactor the monolith when necessary and to test domains in isolation. Spring Modulith provides an in-process eventing mechanism that helps further decouple modules within a single application. Best of all, it integrates with ArchUnit and jmolecules to automate verification of its domain-driven design rules.
