logical separation before process separation

It sounds obvious, but I’ve seen this step skipped so many times. You need to disentangle your code logically before even talking about “microservices” or anything similar. A good first step is to think about consistency boundaries. What data needs to be persisted in one shot? Then start thinking about what logical concepts belong together.

Also, once you’ve logically separated, you can introduce a process boundary without doing all of the infrastructure work to create a microservice. Use internal events. Run the logic in a separate thread. Whatever it takes to get into the async paradigm without investing in a ton of infrastructure. Move to a microservice after doing those things if there is a compelling reason to (computationally expensive, empower a team to fully own their domain).