CODEWITHSUNDEEP
domain-driven-design
umulmrum
umulmrum

Reputation: 183

Event Storming and read events

I'm new to event storming and DDD and haven't read the books yet, so sorry if my question is answered there or already on SO.

So event storming says to model those events that are of interest for a domain expert. This means that read events (say "orders listed") is normally not modelled. I'm struggling with edge-cases here and hope to find help: What if my domain is about things like statistics. Normally it doesn't matter to the domain expert if a single user has a look at statistics, so I would normally omit this. But looking at a more technical level, it might be of great interest, i.e. it might be a complex task to build those statistics, and might be deferred or offloaded to another system. Is it still not modelled? Do I have to use another approach for this type of event, turning the domain event model somewhat incomplete? Or is this an indicator that "statistics generated" and "statistics viewed" are separate things that shouldn't be mixed up?

Thanks for suggestions!

Upvotes: 1

Views: 518

Answers (1)

Levi Ramsey
Levi Ramsey

Reputation: 20551

In general, the only events that you should be modeling are those that change how the system behaves for at least one future task. Very often the domain experts are the people who know what can change behavior.

Typically reads don't change behavior, so they're typically not included in the model.

For a case of building a complex bundle of statistics on demand, this sounds like a saga, where what's being modeled isn't the computation of the statistics, but the workflow of computing the statistics. For this domain, you are plausibly the domain expert, and the events like "this stage completed" are domain events for the saga.

Upvotes: 2

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