sequence-diagramuml
The most likely answer is no, but I've come with this doubt. Can an actor act as a class?
I know actors trigger events and can have prompts, but if there's a class modeling an actor (such as an user class) can we call methods over them? Or is this a complete misunderstanding of the actor role, which is getting mixed with the representative class?
Supposed as correct:
Doubt if correct:
They seem to be correct enough to understand what is going on, which in my opinion is all you need for UML. However if you want to be more technically correct:
Request membership card appears to be a return when it should presumably be a message with provide membership card as a return? confirm membership may not need to go back to the person, but a request for the book name probably shouldOne way is to use Fragments like this:
But honestly: code is much clearer for such purposes. Avoid using a graphical representation where a few lines of (pseudo) code can clarify what a 1000 pictures obfuscate. Once (in the 80s) I also though that programming graphically would be an advantage. But now I'm old an wise and know that this was wishful thinking. It's simply stupid ;-)
Regarding the IOException this heavily depends on runtime behavior. Usually this is a message sent from c which is not a return message but will produce a call stack in a. This can be placed in an alt Fragment.
Best Answer
In UML, an Actor is always something (a system or person) that is outside the scope of the system/software that you are building. It would be completely wrong to equate an actor with an instance/object of a class that happens to model certain aspects of the actor in your system.
In the shown UML diagrams, the actor "User" (with it's stick-figure icon) represents the real-world human being that operates your system. The class
Userrepresents a model of that person that captures the characteristics that are relevant for you. This class only exists within your system.This makes that the class and the actor are two distinct entities and should also be shown as such in your diagrams.