Comments on: Two flavors of DDD

By: Sławek Sobótka

Sławek Sobótka — Tue, 01 Nov 2011 12:31:27 +0000

Great post. It’s good that we are trying to name new patterns in DDD and describe their forces and consequences.

One remark: first approach (Aggregate Graph) is not “more OO”. Actually it’s not OO at all:P
In this approach We are using classes to model data structures, but this doest not mean that using classes automatically imply OO. Traversing “web” of object volatiles two fundamental OO principles: abstraction and encapsulation/hermetisation.

So second approach that decouples objects, and encapsulates (origin of the data in this case) is more OO:)

@bjdavidson – actually it can be considered as a feature. I’m interested in the data that ware actual at the order confirmation moment. If user changes them later – shipment still goes to the “old” address. Of course if this does not make in particular domain it should be modeled as “Aggregate Graph” or just as ID of the customer if customer is in different Bounded Context (CRM module for example).

By: bjdavidson

bjdavidson — Sun, 04 Jul 2010 14:25:38 +0000

What happens if you change the customer name. Do you update the aggregates with the customer snapshot attached? If so isnt this expensive at this point?

By: Martin B. Olesen

Martin B. Olesen — Tue, 17 Nov 2009 12:17:50 +0000

Useful reflections! My own experiences using DDD pretty much mirror yours, but nice to have it put into words.

By: Roger Alsing

Roger Alsing — Fri, 13 Nov 2009 09:22:38 +0000

Snapshots are generally value object and value objects are stored inline in the same table as the owner object.

That is; the product snapshot would be stored together with the order detail data in the same table.

So they are neither projections or separate tables.

By: James Webster

James Webster — Fri, 13 Nov 2009 06:55:27 +0000

Interesting… are the CustomerSnapshot and ProductSnapshot objects just projections of a small set of columns from the database’s Customer and Product tables, or are there actual tables that hold this data?

By: Frans Bouma

Frans Bouma — Mon, 09 Nov 2009 09:35:59 +0000

Insightful as always. :)