kzu
commented
12 years ago Interesting suggestion!
Now, as Orders are event-source, there isn't an easy way to do Orders.Where(State == pending).Sum(Seats)....
So, would you solve that by having a domain service that takes a dependency on the read-model for the other? (which can potentially provide that kind of querying capability?)
/kzu
Daniel Cazzulino | Developer Lead | XML MVP | Clarius Consulting | +1 425.329.3471
On Sun, May 6, 2012 at 10:25 AM, Burtsev Aleksey < reply@reply.github.com
wrote:
I think SeatsAvailability should be a domain service instead of Aggregate.
It doesn't contain state. The two fields it has: remainingSeats, pendingReservations are both calculated, based on Orders. RemainingSeats = totalSeats - (you logic here) for example Reserved+Confirmed. PendingReservations = Orders.Where(State == pending).Sum(Seats).
It perfectly fits a difinition of Domain Service http://domaindrivendesign.org/node/125
Definition: A Service is an operation offered as an interface that stands alone in the model, with no encapsulated state.
Problem: Some concepts from the domain aren't natural to model as objects. Forcing the required domain functionality to be the responsibility of an Entity or Value Object either distorts the definition of a model-based object or adds meaningless artificial objects.
Solution: When a significant process or transformation in the domain is not a natural responsibility of an Entity or Value Object, add an operation to the model as a standalone interface declared as a Service. Define the interface in terms of the language of the model and make sure the operation name is part of the Ubiquitous Language. Make the Service stateless.
Reply to this email directly or view it on GitHub: https://github.com/mspnp/cqrs-journey-code/issues/350
I think SeatsAvailability should be a domain service instead of Aggregate.
It doesn't contain state. The two fields it has: remainingSeats, pendingReservations are both calculated, based on Orders. RemainingSeats = totalSeats - (you logic here) for example Reserved+Confirmed. PendingReservations = Orders.Where(State == pending).Sum(Seats).
It perfectly fits a difinition of Domain Service http://domaindrivendesign.org/node/125
Definition: A Service is an operation offered as an interface that stands alone in the model, with no encapsulated state.
Problem: Some concepts from the domain aren't natural to model as objects. Forcing the required domain functionality to be the responsibility of an Entity or Value Object either distorts the definition of a model-based object or adds meaningless artificial objects.
Solution: When a significant process or transformation in the domain is not a natural responsibility of an Entity or Value Object, add an operation to the model as a standalone interface declared as a Service. Define the interface in terms of the language of the model and make sure the operation name is part of the Ubiquitous Language. Make the Service stateless.