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Clean up your Domain Model with Event Sourcing

I recently had a discussion with a developer who was new to Domain Driven Design, CQRS and Event Sourcing.  They were using Greg Young’s Simple CQRS Example to create there own simple app as learning exercise. After taking a quick look at their aggregate root, one thing that immediately stood out to me was a class field that contained current state.  Why this is interesting is because this field was not in any invariant. When I first started reading and exploring Event Sourcing, this was a big “ah ha!” moment for me. The realization that only certain data within my domain model was really important. We… Read More »Clean up your Domain Model with Event Sourcing

Bounded Context and Subdomains

In a previous blog, I discussed how I recently discovered through eventual consistency that I had poor business alignment.  With more thoughts and insights, I wanted to extend that post by discussion bounded contexts and how they fit within subdomains. 1 to 1? I’ve often thought of a bounded context as being a one-to-one relationship with a subdomain.   To take that further, you may get the impression that they are indeed the same thing.  When I was first introduced to the concept many years ago, I was under the impression that they mapped directly one to one. I’m not entirely… Read More »Bounded Context and Subdomains

Eventual Consistency and Business Alignment

I recently discovered through eventual consistency that my bounded contexts were not properly aligned with the business.   I won’t lie, it took me quite a while to make this realization. This was most likely the case in many situations I’ve had in the past.  Because of this realization, I wanted to let out some of my thoughts about eventual consistency and business alignment. Dependent Bounded Context I’ve often encounter situations where a bounded context requires information that another bounded context is responsible for.  I’d like to use a simple example I’ve heard from Udi Dahan.  In the context of an Ecommerce site. A… Read More »Eventual Consistency and Business Alignment