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A comment on Event Sourcing Is Hard (2019). Parent comment

Re:Event Sourcing Is Hard (2019) by randolorian on Tuesday November 30, 2021 @07:39AM (#29391480)
Seems like a fundamental misunderstanding to me. Commands get validated via your aggregate, not events. Events are not allowed to be rejected. Ever. Because they already happened.
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Re:Event Sourcing Is Hard (2019) by EdwardDiego on Tuesday November 30, 2021 @07:46AM (#29391525)
Thinking that event sourcing and CQRS are synonyms is a fundamental misunderstanding also.

Anyway, pedantry aside, my point remains thus - it's hard to prevent invalid state transitions being submitted to an event sourcing datastore, and when devs can submit events directly, then these invalid transitions will occur.

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Re:Event Sourcing Is Hard (2019) by randolorian on Tuesday November 30, 2021 @08:06AM (#29391670)
> Thinking that event sourcing and CQRS are synonyms is a fundamental misunderstanding also.

Indeed. These are two separate patterns. They can have great synergy when used together but it's not a requirement.

> it's hard to prevent invalid state transitions being submitted to an event sourcing datastore

Apply DDD, use code review, and use stream level ACLs.

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