I grew up using unix where the philosophy is "do one thing and do it well" and I think that carries over well into microservices.
But honestly I'm not sure there is much of a line between the two. I've seen microservices that just return True/False and ones that return 100 lines of json, which are arguably more web-services than microservices.
I honestly think it's a distinction without meaning.
The "do one thing and do it well" Unix philosophy already broke down decades ago when people started adding things like "cat -v" and ability to sort ls and whatnot. People like Doug McIlroy still argue that's all "useless bloat". Pretty much the entire rest of the world disagrees. The point is that "do one thing and do it well" doesn't actually work all that well in reality.
A CLI not a service: there is no operational complexity to "keep things running" in a CLI: you just chain some things together with pipes and that's that. The nice thing about that is that the text interface is generic and you can do things the original authors never thought of. With microservices this usually isn't the case and things are extremely specific. This is also why "do one thing and do it well" doesn't really carry over very well to GUIs.
A lot of microservices I've seen are just functions calls, but with the extra steps of the network stack, gRPC, etc. Some would argue that this is "doing microservices wrong" – and I'd agree – but the reality of the matter is that this is how most people are actually using microservices, and that this is what microservices mean to many people today.
Instead of "microservices" we need to think about "event-driven logic", or something like that. Currently the industry is absolutely obsessed with how you run things, rather than how you design things.
I don't get this idea that modularity and composition can only be achieved with separate processes communicating over a network. There are features within modern programming languages for achieving the same.
I don't think anyone is saying they can only be achieved with separate processes. It's more about independent scaling of the different parts of the system that is the big advantage. That plus the organizational advantages. It's a lot easier to maintain the modularity if you have different groups of engineers working on different services.
it really is a distinction only made by people trying to sell you something or sell you on something. service-oriented architecture is leveraging the power and the curse of being able to connect computers over a network to solve foundational scaling limits of hardware. How granular you want to make things is a design decision.
The attitude. The "micro" of microservices belies a religious zeal that more and smaller services is an unmitigated awesome thing and we should always strive for more of it. "Services" is for people who think it is a necessary evil, to be deployed under the right circumstances.
