Author Topic: Difference between sequence and object instances?  (Read 3071 times)

Martyn

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Difference between sequence and object instances?
« on: June 22, 2004, 03:22:31 am »
Wondered if anyone could help - with a question about the difference between object and sequence instances on a sequence diagram  (EA 4.00.729).

Can create:

* Sequence instance - lifeline dragged from the sequence diagram toolbox.  

* Object instance - by dragging a class from somewhere in the model and "pasting" it as an instance (object).  

The difficulty I am having, appreciating, is why I can't convert a sequence instance to an object instance.  I can "Set Instance Classifier" of a sequence instance to a class and then I would have thought it was an object instance.  But it remains a sequence instance.  I've also tried changing the "type" of a sequence instance to object instance after and it doesn't allow me to change it.

I don't know if I'm fighting UML or EA.

Any comments would be appreciated.

thanks
Martyn

Josť Farinha

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Re: Difference between sequence and object instances?
« Reply #1 on: July 21, 2017, 02:50:43 am »
I have this same question.

Does it mean that an object instance represents a specific object, while a sequence instance represents a variable that may might reference different objects along the way? UML doesn't establish such a differentiation, but I've been feeling that these are two distinct semantics for lifelines, and both are useful.

Thanks for your attention
Josť

qwerty

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Re: Difference between sequence and object instances?
« Reply #2 on: July 21, 2017, 05:59:46 am »
The difference is EAUI. Lifelines represent objects. Don't care that EA has two methods to create them.

q.