I like them for modularity, message queues and asynchronous events. But you are correct, esp. last one.
On the other hand, why not a monolith and single instance? If one uses a performant language one would be amazed how much can run on a single machine. If one expects growth one should have some plan to scale, sure, but if one does not go for shenanigans like running queues and the like between applications using some form of RCP one might get amazed how much your single monolith can actually do. All this extra networks stuff and so on is not exactly free.
Single points of failure are bad. I agree its orthogonal, which is why I inquired further about the, imo, odd suggestion.
Team being the keyword here. If you have 3-5 developers per microservice, you're absolutely okay. If you have 3-5 microservices per developer, that's when it gets ugly.
> heck even a different language
There's nothing about writing software in different languages that necessitates separating functionality with HTTP calls.
I mean it's only computers and the only limit to what we can make them do is our imagination.
In this case though for the sake of argument what options would I have if I, say, needed to let a remote team add some functionality to my, say, Spring backend but they really prefer to write C# and have their own CI/CD system. I'm not sure how I would accomplish this in a monolith.
With a library.
Depending on what you’re doing (process ran a few times a day?), maybe even spawning a process is enough.
> what options would I have if I, say, needed to let a remote team add some functionality to my, say, Spring backend but they really prefer to write C# and have their own CI/CD system.
That sounds like you need at most two different services, not microservices.
I don't know what that library is right now. Meanwhile I could set up the separate repos/microservices by the end of the day.
> That sounds like you need at most two different services, not microservices
It is unfortunate that the "micro" in "microservice" is often misunderstood to expect that these are very small and granular components. In practice by and large it ends up being separate services with separate repo, code review, ownership, deploy or CI/CD etc. pipelines. It doesn't have to mean they are actually very small. I know people like to joke about npm components and the leftpad thing but in my experience microservices have not turned out like that.
Are you serious? In which language do you program that you don't have to use multiple libraries daily? You just talked about NPM.
In your example, the C# could output DLLs that have functions that can be called by the Java code. This can give the same encapsulation you get with your multiple services example, including separate deployments, different repo, different language, etc.
You could also use different processes. Please tell me you know what an executable is...
> Meanwhile I could set up the separate repos/microservices by the end of the day
That's because someone set it up for you, not because it's faster.
In your hypothetical scenario of "I needed to let a remote team add some functionality to my, say, Spring backend but they really prefer to write C# and have their own CI/CD system" you didn't mention that "…but we already have a fast way of setting up micro services".
> It is unfortunate that the "micro" in "microservice" is often misunderstood*
It's not, you're using the term loosely. "Two services" do not make a micro service architecture.
Sorry to be blunt, but I'm getting the feeling you're not talking out of experience, but rather repeating popular talking points.
I said I don't know which library would let me make C# method calls from a Java Spring runtime, presumably in the same process. Do you? Feel free to share a link.
> That's because someone set it up for you, not because it's faster.
Yes, the whole point was to come up with a concrete example for the sake of argument, and see how we can accomplish it in practice. We're not writing academic papers here, the fact that this functionality is widely available is a good thing.
> It's not, you're using the term loosely
Yes, me and 95% of the industry. Again, it's unfortunate but here we are.
You don't need a library for that, it's is part of the language. Java can call code from native libraries, C# can export native functions. It can also be another process. [1]
> Yes, the whole point was to come up with a concrete example for the sake of argument, and see how we can accomplish it in practice. We're not writing academic papers here, the fact that this functionality is widely available is a good thing.
The problem is that you moved the goalposts. "I need to interoperate with C# code" is very different from "I need to interoperate with C# code and my company uses microservices and that's the only thing I know".
You can't claim something is automatically worse just because you're ignorant about it.
> Yes, me and 95% of the industry. Again, it's unfortunate but here we are.
Nope. There are exactly zero companies claiming to use microservices when they have exact two services. And it's not about size, by the way, it's about different architectural patterns.
Having never done this, I believe you. I am still skeptical of how quickly/effectively you could set up a CI/CD system and the module repos to deploy to a monolith. I wonder how the type interop works there (equivalent of OpenAPI-based code generation).
> The problem is that you moved the goalposts. "I need to interoperate with C# code" is very different from "I need to interoperate with C# code and my company uses microservices and that's the only thing I know".
That's maybe a bit unfair. There are a lot of microservice shops, but I haven't heard many who do this Franken-monolith thing. Remember that infamous microservice dependency graph from Uber? I guess Facebook was famous for doing a monolith but I don't know if it was purely PHP or not.
> You can't claim something is automatically worse just because you're ignorant about it.
I can if the metric is availability/familiarity in the industry, but OK.
> Nope. There are exactly zero companies claiming to use microservices when they have exact two services. And it's not about size, by the way, it's about different architectural patterns.
I don't know, my experience is people like to say they use microservices but they just have a service-oriented architecture. Meanwhile I never ran across an organization that does something like npm modules and goes way crazy with granular services. I don't know, maybe they are out there.
Your original example was that you "needed to let a remote team add some functionality to my, say, Spring backend but they really prefer to write C# and have their own CI/CD system". I am telling you the classical way of solving this problem. You don't get to change the constraints ("I already know how to setup X") after an answer just to say the answer is wrong/worse and expect not to be called out on it...
Also: It's not a Franken-monolith, dude... it's just a library. Have you ever used ImageMagick to resize images from your microservices? Maybe made a request using libcurl? Maybe had to use a SQL driver that was native, maybe Redis? A NPM package with native code? That's exactly the same thing... I literally don't know of a single language that doesn't use those things...
Plus, there is a HUGE difference between what you asked and a Uber/Facebook scenario. You seem to be under the impression that what I'm suggesting is a replacement for real microservices. No, it is simply a solution for the problem you described.
You described a problem and said you don't know how to solve other than with X. I'm giving you Y. I don't understand what's the issue here.
> I can if the metric is availability/familiarity in the industry, but OK.
Sure, but you can't use yourself as a benchmark for the industry if you're that unfamiliar with something that basic.
> I don't know, my experience is people like to say they use microservices but they just have a service-oriented architecture. Meanwhile I never ran across an organization that does something like npm modules and goes way crazy with granular services. I don't know, maybe they are out there.
Again, there is a humongous difference between "we're doing microservices" or even "we have a service oriented architecture" and your "I need two things to interoperate".
I don't see it as being called out, it's a constructive discussion. The purpose of my example is to see how practical it would be for me to set up a monolith-based CI/CD that could support multi-lingual, multi-repo teams. I have a better idea now, maybe have them publish to a local Maven style server, and kick off a monolith build when there is a new library version? The monolith can then bind them together and rebuild. I'm not sure how the host interfaces would get regenerated still.
Good examples re: libcurl, ImageMagick, etc. How would we deal with very frequent changes there? I know that upgrading a SQL driver is not a task we take lightly, and I would love to see how we could make this easy to do on a daily or hourly basis. Mainly we'd need auto-generated strong types somewhere on the interface, again, like OpenAPI but for libraries.
> You seem to be under the impression that what I'm suggesting is a replacement for real microservices.
This discussion started with several suggestions that monoliths could do just as well as most microservice setups, and I wanted to do an exercise to see how practical this would be.
> I don't understand what's the issue here.
There is no issue. Who said there is an issue? So far so good.
> Sure, but you can't use yourself as a benchmark for the industry if you're that unfamiliar with something that basic.
I know and/or interview enough people across the web-dev and game-dev industry that I feel I have a sizable sample of data points to form an opinion that is not purely a guess of a single person.
> Again, there is a humongous difference between "we're doing microservices" or even "we have a service oriented architecture" and your "I need two things to interoperate".
Sure. The two things example was just a distilled example for the purpose of a thought experiment. We can easily extrapolate to an org with tens of services where maybe most people like to use the default environment like Java/Spring but a few teams maybe prefer or their use case calls for something different like Python or C# or whatever. If anything it would be even more difficult to stand up a monolith there with more and more varied components.
Updating SQL drivers, etc, is not trivial because you don't have control over the code, but if you have enough integration tests (or at least proper failure handling) for your separate library then you can update with the same frequency as microservices.
I think it's fine to do this thought exercise, but you're massively discounting the difficulties of microservices, while making up obstacles and mocking ("Franken-monolith") every other suggestion. Any company that doesn't already use microservices (and doesn't also have people with experience building infrastructure for them, rather than just using) is gonna have a harder time with a microservice solution than you currently do. It is perfectly fine to extrapolate from your own experience, but you're discount things without any research whatsoever and saying "nobody knows about it" or "nobody uses it" in a very disrespectful way. Another post of this discussion about code ownership is exactly the same: it takes literally seconds to write a simple codeowners file in GitHub, while you make it seem like it would be an Sisyphean task ("an uphill battle") compared with microservices just because you're not aware of it. Some things are not hard, maybe you just didn't heard of them yet.
Also if individual devs can reach out across the codebase and turn private methods public, it is the pull request review procedure that you need to improve, not the architecture.
In the real world, poorly designed microservices make the ball of mud problem much, much worse, and whatever pain you had in deployments in a monolith are now magnified ten-fold. I have not been fortunate enough to see well-designed microservices, so I suspect the ball of mud is the default. Can this be rectified through discipline? Probably, but I haven't seen it.
Asynchronous? Doesn't save you, when an upstream service changes event definitions and emits events with unexpected structure, and a downstream service starts failing. Can this be rectified through Async OpenAPI and rigorous contract testing? Probably, but I haven't seen this happen in a way that helps.
I have seen large companies survive perfectly well on a monolithic ball of mud, and small companies get lost in a mud pit of microservices.
My point is not that microservices are bad, they're not, they're just a tool, but they are a tool that is a poor fit for most companies, in my opinion. I can't speak to the few giant companies that need them and use them effectively; there is a good reason the tool exists.
I can see that. I am trying to reflect on why I have such negative experience with a monolith and positive with microservices. It's possible that in the monolith setups I had, poor design was easy by default. No linting, no cross-module ownership interlocks, very slow and costly production deploys. Likewise the microservice setups tended to make poor design harder since code is isolated by default both at compile and runtime.
Can you make a monolith with all the good benefits of modularity but without the complications of network RPC etc.? Maybe, but I haven't seen it yet. (Excluding trivial single-team apps; talking about at least 3 teams and 50+ headcount orgs).
> Asynchronous? Doesn't save you, when an upstream service changes event definitions and emits events with unexpected structure, and a downstream service starts failing
Sure, shit happens. Again my experience may be colored, but when costly mistakes happen in monoliths, it tended to take longer to roll back because of how deploys are structured both technically and on an organizational level. I think I would still prefer smaller units in this case.
If "any developer" can do it, then the problem is not with monoliths, but rather with your pull request reviews process and lack of code ownership. This can even be helped by Github and other platforms with a CODEOWNERS file.
Microservices by themselves doesn't solve this problem. If anyone has commit access to all micro services, then they can make an even bigger mess, the same way.
If you’re using microservices + monorepo, you need exactly the same thing, otherwise people will just commit in your service.
If you’re relying on multiple repositories, you can just split things within libraries and have the exact same effect. You can even have separate deployments with this arrangement.
Not to mention it is also an “uphill battle to get things set up properly” with microservices, so there’s really no advantage in using them for enforcing encapsulation.
But most important: a team unable to enforce encapsulation and code ownership is not ready for microservices at all.