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Difference between "extends" and "generalize"!!!
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Posted By:   Mario_Tigua
Posted On:   Saturday, September 11, 2004 09:38 AM

Hi everyone, I have the following questions: 1. Whats difference between extends and generalize? Could you explain me this with an example? Exists a rule what says "Apply generalize when you identify a new business rule" but I don´t understand this. 2. Is possible to communicate an actor with an extended use case? In what case is recomendable do this? 3. Is possible to communicate an actor with an include use case? In what case is recomendable do this? 4. Is possible to communicate an actor with an specialized use case? In what case is recomendable do this? 5. If an actor have access to a base use case, by means of a communicaton line, he have access to a extended use case too?    More>>

Hi everyone, I have the following questions:

1. Whats difference between extends and generalize? Could you explain me this with an example?
Exists a rule what says "Apply generalize when you identify a new business rule" but I don´t understand this.

2. Is possible to communicate an actor with an extended use case? In what case is recomendable do this?

3. Is possible to communicate an actor with an include use case? In what case is recomendable do this?

4. Is possible to communicate an actor with an specialized use case? In what case is recomendable do this?

5. If an actor have access to a base use case, by means of a communicaton line, he have access to a extended use case too?
Actor-------Base <-----Extended.


Thanks,
Mario.


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Re: Difference between "extends" and "generalize"!!!

Posted By:   Guruprasad_LR  
Posted On:   Tuesday, September 21, 2004 04:58 AM

The basic difference between extends and generalize is that both of them are opposites. To extend is to specialize a use case.





Basically when you are extending an use case which is generic, you will add specifications which will work under a given set of circumstances and hence you are making it specialized.





Let us take a simple use case of a passenger trying to buy a subway train ticket from a ticket vending machine.



Passenger ----> Deposit Money



Now Deposit Money can be extended by two use cases namely "Deposit Coins" and "Deposit Notes".



These individual use cases are now extended use cases of the generic use case "Deposit Money"





However the reverse will happen when you are generalizing. You take a specific interaction , remove all the circumstantial specifications from it, then you have a generalization.





The same relationship can be envisaged as a generalization or a specialization(extend) based on the direction of traversal of the relationship.





Hope this helps


Regards

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