One issue with any form of modularization is that dependency cycles are not desirable and have the side effect of creating a need for ever more modules. The reason is that any dependency cycle can be trivially broken by adding another module.
You get dependency cycles when two dependent services need the same thing and you lack a good place to put that thing. You start with modules A and B. Then B need something that A has and then A needs something that B has. You can't do it without introducing a dependency cycle. So, you introduce C with the new thing. And A and B depend on C but B still also depends on A. And so on.
True weather you do Corba, COM, SOAP, Web RPC, OSGi, Gradle modules, etc. The only difference is the overhead of creating those modules is different and has varying levels of ceremony, management needs, etc. Also refactoring the module structure gets more complicated with some of these. And that's important because an organically grown architecture inevitably needs refactoring. And that tends to be a lot more tedious once you have micro services. And inevitably you will need to refactor. Unless you did waterfall perfectly and got the architecture and modularization right in one go. Hint: you won't.
Finally, the same kind of design principles you use for structuring your code (e.g. SOLID, keeping things cohesive, maximizing cohesiveness, Demeter's law, etc.) also applies to module design. Services with lots of outgoing dependencies are a problem. Services that do too much (low cohesiveness are a problem). Services that skip layers are a problem. The solutions are the same: refactor and change the design. Except that's harder with micro-services.
That's why Martin Fowler is right. Start with a monolith. Nothing wrong with those and should not stop you practicing good design. Using microservices actually makes it harder to do so. So, don't introduce microservices until you have to for a good technical or organizational reason (i.e. Conway's law can be a thing). But don't do it for the wrong reason of it being the hip thing to do.
It doesn't but it simplifies moving stuff around. I use an IDE and can rename at will. With microservice, it's rename. Commit, wait for the thing to build and deploy, open a different project fix all the names, etc. That requires a lot of coordination and is also risky if you get it wrong.
With a monolith, you change everything, create 1 commit. And after that passes CI/CD it can be live in minutes.
You get dependency cycles when two dependent services need the same thing and you lack a good place to put that thing. You start with modules A and B. Then B need something that A has and then A needs something that B has. You can't do it without introducing a dependency cycle. So, you introduce C with the new thing. And A and B depend on C but B still also depends on A. And so on.
True weather you do Corba, COM, SOAP, Web RPC, OSGi, Gradle modules, etc. The only difference is the overhead of creating those modules is different and has varying levels of ceremony, management needs, etc. Also refactoring the module structure gets more complicated with some of these. And that's important because an organically grown architecture inevitably needs refactoring. And that tends to be a lot more tedious once you have micro services. And inevitably you will need to refactor. Unless you did waterfall perfectly and got the architecture and modularization right in one go. Hint: you won't.
Finally, the same kind of design principles you use for structuring your code (e.g. SOLID, keeping things cohesive, maximizing cohesiveness, Demeter's law, etc.) also applies to module design. Services with lots of outgoing dependencies are a problem. Services that do too much (low cohesiveness are a problem). Services that skip layers are a problem. The solutions are the same: refactor and change the design. Except that's harder with micro-services.
That's why Martin Fowler is right. Start with a monolith. Nothing wrong with those and should not stop you practicing good design. Using microservices actually makes it harder to do so. So, don't introduce microservices until you have to for a good technical or organizational reason (i.e. Conway's law can be a thing). But don't do it for the wrong reason of it being the hip thing to do.