Bruce Prior | 6 Jul 2012 17:24
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Object Domain

I see the term object domain used a lot these days but I'm hardpressed to understand what it actually is.

Can someone please tell me what an object domain is and perhaps give an example?

many thanks.

Bruce Prior
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Chris Cunnington | 6 Jul 2012 17:30
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Re: Object Domain

On 12-07-06 11:24 AM, Bruce Prior wrote:
I see the term object domain used a lot these days but I'm hardpressed to understand what it actually is.

Can someone please tell me what an object domain is and perhaps give an example?

many thanks.

Bruce Prior


_______________________________________________ Beginners mailing list Beginners <at> lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
I'll take a shot and somebody can correct me. The domain is related to your data, your database, how you modeled the problem into pieces of data. So the object domain would be the objects related to holding or delivering data from you persistence/database.

In the MVC, model/view/controller, pattern the model is the data/database. The view presents it to an input device i.e. screen or web page. The controllers work between the two.

The object domain would be the model objects. A SQL database, say.

That's my take.

Chris

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David Mitchell | 6 Jul 2012 23:42
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Re: Object Domain

If you were modeling a soda can vending machine, you might have classes to model the domain including Can, Money, and Dispenser. Example from: http://www.amazon.com/Object-Oriented-Programming-Yourdon-Press-Computing/dp/013032616X

I think a lot of people think of the domain as the database, but I've always thought of the database as how you store your domain model, not the domain model itself. 

The object store is concerned with state. Domain objects have state and behavior.


Note that many systems written in object-oriented languages don't have domain models by this definition. Compare with, say, Table Model from the same book.

--David Mitchell ( <at> davidmitchell)



On Fri, Jul 6, 2012 at 10:30 AM, Chris Cunnington <smalltalktelevision <at> gmail.com> wrote:
On 12-07-06 11:24 AM, Bruce Prior wrote:
I see the term object domain used a lot these days but I'm hardpressed to understand what it actually is.

Can someone please tell me what an object domain is and perhaps give an example?

many thanks.

Bruce Prior


_______________________________________________ Beginners mailing list Beginners <at> lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
I'll take a shot and somebody can correct me. The domain is related to your data, your database, how you modeled the problem into pieces of data. So the object domain would be the objects related to holding or delivering data from you persistence/database.

In the MVC, model/view/controller, pattern the model is the data/database. The view presents it to an input device i.e. screen or web page. The controllers work between the two.

The object domain would be the model objects. A SQL database, say.

That's my take.

Chris


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Casey Ransberger | 7 Jul 2012 19:17
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Re: Object Domain

I agree with David's statement below, generally. It's worth noting that in Smalltalk, our object memory +
virtual machine together serve as a kind of non-relational database which preserves both state and
behavior, but one doesn't generally have to think about it and that's beautiful:)

Even in SQL one has triggers and stored procedures, so perhaps the distinction is pervasively arbitrary.
Someday we may have fast non-volatile RAM and no separate long term storage, at which point databases and
persistence as we popularly think about them may even disappear entirely.

One of Smalltalk's offspring, the Self language, uses message sends (as far as the programmer is
concerned) to access state, and thus does away with assignment in the usual/low-level sense. This is fun
to think about (for me anyway!) 

Someone please correct me if I'm wrong here, but I think of "object domain" and "object model" (where the
word model is distinct from and more general than the Model in MVC) as being interchangeable. 

I think of an object domain as just the set of objects which implements a feature or solves a problem. I
suppose I may have my terminology mixed up though, so sound off if I'm wrong here folks:) 

--Casey Ransberger

On Jul 6, 2012, at 2:42 PM, David Mitchell <david.mitchell <at> gmail.com> wrote:

> I think a lot of people think of the domain as the database, but I've always thought of the database as how you
store your domain model, not the domain model itself. 

Gmane