2021'Jun 01

DDD - Aggregates

Aggregates live within 202105192148 DDD - Bounded Contexts. I'll try my best to grasp the concept, but I confess that I don't have a clear picture yet.

Aggregates are composed by 202106010842 DDD - Entities and 202106010843 DDD - Value objects. Also, they always have a root entity, everything else derive from it.

Usually these are defined by some sort of business transaction. I.e: we can have a Order aggregate composed of OrderItem value objects. The order can canceled (which would be defined by the status == CANCELED 202106010845 DDD - Invariants|invariant) or the order can be finished when status == FINISHED.

Material that helped me a bit in understanding aggregates (although I don't get it ATM):

https://thepaulrayner.com/blog/aggregates-and-entities-in-domain-driven-design/
https://martinfowler.com/bliki/DDD_Aggregate.html

#todo: This is a mess. Need to make a second attempt to grok this

[#vaughn-ddddis]: Vernon, Vaughn. Domain-Driven Design Distilled. Boston: Addison-Wesley, 2016.