A well-defined business model to me sounds like a Bounded Context. Splitting that into 25-50 very small parts is the opposite of well defined.
Heath @cant_unlearn
12 Apr 2020
Replying to @VaughnVernon
One thing to consider is if they have a well defined business model that they understand and can see the property boundaries. Sometimes these things just make sense from the start. But you are right, for most cases it is not where you start
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I was referring to the context, it is very early where I am :). I agree with you, I have never built a microservice > 4 services. The business never modeled itself that way. I can't imagine trying to manage or do change control on 20+, crazy.
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Hey, Heath! I am in Arizona so on the same wall clock as you. Thanks for your comments. I didn't mean to step on your toes. This whole bbom-monolith-micro-now-macro thing has and will cause so many problems. Someone at BigCo launches a new really bad name and everyone jumps.
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Please take the lead and name this as "bounded services / bounded apps" :) .
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There is an existing name/pattern that describes this fairly well: Self-Contained Systems. I have issues with the name and a few definitions, but it is definitely a great place to start. /cc @stilkov @bitboss - "System" - too broad - "core domain" - nope scs-architecture.org/
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Thanks, & would love to hear your feedback in more detail, Vaughn
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Briefly - System (also) has too many meanings. I've concluded that N deployed independent Bounded Contexts are together a System. However, I am pretty sure that Donella H. Meadows would agree that an SCS is indeed a System.
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- In the SCS infodeck is a statement that within a SCS there are potentially multiple domains and a core domain. I assume it means "models." Although this ok with DDD, I think that it is spelled "Core Domain" and means differentiating value. I think of Core Domain == SCS.
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In other words, a Core Domain is not just the most important model in any ol' Bounded Context. Also we should strive for 1:1 model and Bounded Context. For example, a Supporting Subdomain could possibly have that situation, but it is definitely not a DDD "Core Domain."
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This is, of course, in terms of DDD. Perhaps you didn't have DDD precisely in mind when you codified SCS. So it's understandable that you could have the case of multiple models and the most important model in one SCS.
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Replying to @VaughnVernon @polarbit29 @bitboss
Thank you. I’ll leave the discussion of DDD terminology to one of my more knowledgeable colleagues. Personally, I like an SCS to be the physical instantiation of, or wrapper around, one bounded context, including its interfaces to the outside world.

Apr 12, 2020 · 2:58 PM UTC

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Replying to @stilkov @VaughnVernon @polarbit29 @bitboss
From my limited understanding, the core domain (in DDD terms) could be spread across multiple SCSs, but doesn’t have to be
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To me multiple SCS for on Core Domain sounds like tiny microservices. But the infodeck basically says the opposite: SCS == M models 1 Core.
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