What are the kinds of practical difficulties you've run into when implementing Microfrontends?

How many people are working on this application?

The main benefit of microservices is making teams more independent, and the code should follow due to conway's law. But microservices also has a significant overhead costs, and there is a risk of creating a distributed big ball of mud if you are not careful.

As for microfrontends, I will just recommend to do a fair bit of experimentation and prototyping so you learn the pattern and tools before committing to anything. And be prepared to change if something is not working.

I don't have any experience with microfrontends, just experience with a distributed monolith that would probably be better if it used a traditional server/client architecture.

Just reading the definition of "microfrontend" I would assume that each team writes the part of the UI that interacts with their service. And that all individual UI parts are somehow integrated into a cohesive whole. So the product team handles the product pages, the user team handle the login and user pages etc.

Managing things like numeric or address inputs etc sounds more like a traditional library. But that will introduce some issues. Either you allow different services use different versions of the library and accept some inconsistencies. Or you deploy the library independently, forcing all services to use the newest version, and suffer from the dependency and testing problems that implies.

To me, this plan sounds like it has high risk, and I think that reducing risk is good advice when introducing any new technology. But I freely admit I'm biased, and I cannot claim to be an expert on the topic.

The basic building block components (provided by Svelte in your case) still need to be further composed into functional units.

Relatively simple example: a user entering a numeric value should have basically the same experience across all pages which require a numeric value. The range of allowed values might vary, but how the label and validation are displayed should be consistent.

More complex example: a user entering an address should have basically the same experience across all pages which require an address. The range of allowed addresses (maybe only certain countries) might vary, but how the labels and validation messages are displayed should be consistent.

Of course, how labels and validation messages are displayed should be consistent across all components.

This can lead to a component library(ies) that is expected to be used across all pages. The lib provides the consistency, where each page injects the properties/callbacks needed for that specific page. Figuring out the granularity of the component lib is really really really hard.

"What are the kinds of practical difficulties you've run into when implementing Microfrontends?" Is it really that or are you rather looking for problems and solutions that arise when refactoring from monolith to a more "microservice"-ish architecture?

Your question would be improved a lot if you could explain what the term "micro-frontend" means to you.

...bBecause to me, it makes me think of HATEOS; but another valid, but entirely distinct, interpretation is to imagine a kind-of minimal SPA running back-in-the-day when OIDC implicit flow wasn't considered a massive security problem. ...or do you mean like the embedded-mini-apps you get in something like China's WeChat? (Or hell: skip the bloated Chromium browser entirely and make your "frontend" a simple Perl or Bash script that drives curl).

@Fildor Microfrontends are usually an evolutionary step aren't they? I think my question centers more on what other people have experienced and what their situations were when they implemented Microfrontends to gather knowledge from the trenches. I'd like to know the challenges other people have come across to get some ideas of different areas of risk and mitigation.

@JonasH there will be around 50 people if I recall the last numbers. Though I'm mainly curious about your experiences in implementing microfrontends. Please share what you think is relevant to situations you've come across.

@AndrewS this is exactly the kind of examples and experience I'm looking for. Thank you so much!

@Dai I added this link to the original question. I'm also curious how other people might define it, but the definition I've seen used most is:

An architectural style where independently deliverable frontend applications are composed into a greater whole.