Re: Why can't each Aggregate Root have its own collections of entities/ARs?

Most "systems" do.

On Thursday, August 29, 2013, Maykonn Welington Candido wrote:

> **
>
>
> I was thinking about it. A system can have multiple domains?
>
> ------------------------------
> To: [email protected] <javascript:_e({}, 'cvml',
> '[email protected]');>
> From: [email protected] <javascript:_e({}, 'cvml', '[email protected]');>
> Date: Thu, 29 Aug 2013 10:19:42 +0200
> Subject: Re: [domaindrivendesign] Why can't each Aggregate Root have its
> own collections of entities/ARs?
>
>
>
> No, I would prefer to have a list of continents
>
>  class World {
>    List<Continent> continents = ...;
>  }
>
>
>  Because decoupling world and continents via id's and messages seem like
> overkill.
>
> Now, if we were to switch from the domain of topography (the structure of
> the world), to, say, financial data associated with the topography (the
> financial domain), then I can see a decoupling. The Topography domain sends
> messages to any other domain, like Financial, or Demography or whatever,
> about changes in its model.
>
> Then why not all one domain model? Because the Topography model may hold
> detailed information on the continents, countries, their borders, how to
> render, etc which has no meaning in other domains. In the other domains the
> entities just "are" a country without all the extra weight. By decoupling
> and creating adapters, each domain may evolve independent of the others.
>
> Tom
>
>
>
>
>
>
> On 2013-08-29 10:06, Jorge Branco wrote:
>
>
>  Hi again!
>
>  Tom,
>
>   Now if you take that further and say that a World needs to know how
> many Countries each Continent has to perform it's responsibilities, the
> only data that the World AR needs to hold is a map of ContinentID to
> Country count, again maintained via domain events.
>
>
>
>  If I understood you correctly, you're favoring a solution along the
> lines of:
>
>   class World {
>    Map<ContinentId, Integer> continentsSize = ...;
>  }
>
>
>  that from its inception on is updated via domain events. But if this is
> indeed the case, how would you deal with this if World needed also other
> things from continents other than size? Would you have a map for each one
> of the needed features?
>
>  jorge
>
>
> On Thu, Aug 29, 2013 at 7:54 AM, Tom Eugelink <[email protected]> wrote:
>
>
>
> Hi Dennis,
>
> Good question; neither I guess, I'm voicing an opinion.
>
> In an earlier post I said that I understand the reason for this
> disconnected model, and I really do see the upside. I'm not closed minded,
> but I also see the downside. And I'm really in doubt if the gain outweighs
> the loss.
>
>
>
>
>
>
> On 2013-08-
>
>  
>


-- 
Le doute n'est pas une condition agréable, mais la certitude est absurde.