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Help with Domain Model Assumptions

Fernando Franzini
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Joined: Jan 09, 2009
Posts: 486
    
    2

Hello Ranchers

I need help for finish my project.
In the class diagram domain model of my assignment there are 12 classes. But 4 classes are not mentioned in the descriptions of the use cases. That is, I have no information on what to do with these classes ... where create, where persists, where recover etc .... how to relate to other ...
In this case I'm trying to make some assumptions, but these classes are very specific things and I really do not know what to do ....
What to do in such cases?
Regards.


Fernando Franzini - Java Blog
Nimit Shah
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Joined: Jul 02, 2007
Posts: 53
I think it would be good to research a bit about domain and then mention assumptions.
Fernando Franzini
Ranch Hand

Joined: Jan 09, 2009
Posts: 486
    
    2

I have the following entities:

SellOrder -> Buyer has 1 (1-1)
SellOrder -> BuyerPayment has many (1-N).

But there is not any information on how to select the buyer and the amount and form of payment.
My assignment is written "All of the objects and relationships Should be Addressed in your design and implementation"
I was almost finished and now I'm completely stopped ....
Any idea?
Regards
Rajeev Rnair
Ranch Hand

Joined: Mar 22, 2010
Posts: 308

Hi Fernando,
Can you please explain what the issue is?
I see that SellOrder -> Buyer is a 1-1 relation; One sellorder will have one buyer and one buyer will have one sell order
Sellorder -> BuyerPayment is a 1-N relation; one sell order can have one BuyerPayment or multiple BuyerPayments; Buyer can pay partially
You need to assume payment mode (like credit card, debit etc) and clearly mention in your Assumptions

Admins, I hope this discussion is in the scope of this forum, other wise please delete my post

Thanks,


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Fernando Franzini
Ranch Hand

Joined: Jan 09, 2009
Posts: 486
    
    2

Hello Rajeev

This is precisely the problem! The entities ONLY appear in the diagram domain model but has no text saying something about ... That is, I do not know what to do with these entities ....
Rajeev Rnair
Ranch Hand

Joined: Mar 22, 2010
Posts: 308

Oh I got it; the above entities has nothing to do with any of your use cases! right?
Assuming these 2 entities doesn't have any relation with any of other classes. Please confirm
If it is possible to relate to any other entities (direclty or indirectly), try to do that and mention it in assumptions!
If that is the case, just put these two in the class diagram, and mention in assumptions that you are putting there because it was there in the domain model.

At least in my case, all entities were related; even though I had to change the relationship two places. I clearly mentioned that in the assumptions and without that change I couldn't have progressed


Good luck!
Fernando Franzini
Ranch Hand

Joined: Jan 09, 2009
Posts: 486
    
    2

Oh I got it; the above entities has nothing to do with any of your use cases! right?

yeap!!

Assuming these 2 entities doesn't have any relation with any of other classes. Please confirm

Relationship is yes ... what do not have is information for me to do something with them ...

If that is the case, just put these two in the class diagram, and mention in assumptions that you are putting there because it was there in the domain model.

I just put but not design anything with them?

At least in my case, all entities were related; even though I had to change the relationship two places. I clearly mentioned that in the assumptions and without that change I couldn't have progressed

I also have wrong relationships in the domain model diagram ...See below:

Buyer (1) -> (N) SellOrder (N) -> (N)BuyerPayment (1) ->(N) Buyer
That makes no sense PaymentBuyer has many Buyer!

Another thing, my assignment has wrong things like texts and pictures that do not exist as "Retired Early Trading Online" ... To me it seems error CLTR+V and CLTR+V cause my assignament is about Geamstone International.
Do you think I should fix the relationship and justify it?

Regards Rajeev

Rajeev Rnair
Ranch Hand

Joined: Mar 22, 2010
Posts: 308

I think you should correct the relationship in your domain model and explain it in your assumptions
I did so and I passed anyways I hadd Utility Intl assignment
They deliberately make errors in SCEA domain models ; As an architect, it is your responsibility to correct it with something which makes sense
Fernando Franzini
Ranch Hand

Joined: Jan 09, 2009
Posts: 486
    
    2

Thanks Rajeev

I will summarize:

I've got 2 problems...

First is that I have 4 entities in my diagram with no information about them in which I have no idea what to do with them. All use case descriptions do not mention anything about any of them.

Second, 2 these 4 entities has wrong relationships.

So what to do?

Option 1 - do nothing - just put them in my class diagram and explain that they came in the diagram of the document but without any information. I will not need to correct the wrong relationships because I'm not doing anything with them. Here I will totally disregard the 4 entities outside the scope of my project. I'm concerned that assignment says that I must consider all entities in my project ... I really do not know ...

Possibility 2 - fix relationships, making the assumption of how and where to use, designing something with them ...Here also is complicated because I have to invent something to provide some implementation for these four entities ... that will increase my diagrams and design solutions.

you have any other possibility?
Regards.
Fernando Franzini
Ranch Hand

Joined: Jan 09, 2009
Posts: 486
    
    2

I'm seriously considering using option 1.
What do you think?
Regards.
Rajeev Rnair
Ranch Hand

Joined: Mar 22, 2010
Posts: 308

Are you sure the above mentioned entities are NO way related to others in the domain model?
Are they totally out of place with other entities?
None of the above entities can be used with respect to your use cases with certain assumptions?

If the answer is Yes, it is strange! There must be a reason for the examiners to put them in the domain model

To be honest I cannot answer your question without seeing the domain model and description of assignment
If it can be connected anyway with other classes / use cases, I will go with option #2

Fernando Franzini
Ranch Hand

Joined: Jan 09, 2009
Posts: 486
    
    2

Hi Rajeev
My domain model diagram has 16 classes. All classes are properly related. The descriptive use cases provide information only about 12 classes in this diagram. What I mean is that they gave me a diagram with 16 classes and use cases using only 12. I'm lost because leftovers 4 classes that I do not know what to do ... Make assumptions about these 4 classes will increase my solution and my diagrams. And that is a path I'd like to avoid getting ... inventing things there and then having to create solutions to this.
The feeling I have is that these classes should not be in the diagram because use cases are simply not using.
Thanks for help.....
 
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