UML Activity Diagram :loop on decision node

Question

I am learning UML and I would like to know if it is possible to loop on the decision node. Because in my cockburn I have :

3-Enter with ticket
3a1-Enter with card 3a2-Failure: return to 1

If it is possible, how can I do it with Visual Paradigm? Thanks!

What does "return to 1" mean? – Jim L. Apr 01 '17 at 14:09 — Jim L., Apr 01 '17 at 14:09

score 1 · Answer 1 · answered Apr 01 '17 at 17:35

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You can't do that in UML. A decision node is just for evaluation of a condition previously set in an action.

From your scenario it's not obvious how you want to establish a loop anyway. I would guess that the case "none selected" needs to be modeled. Just make your action above not deliver anything else but the ticket/card conditions.

answered Apr 01 '17 at 17:35

qwerty_so

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What do you mean by "Just make your action above not deliver anything else but the ticket/card conditions."?Thank you – Takichiii Apr 04 '17 at 22:23
The action above the decision is something like "ask for payment procedure" (I guess). And that will only continue after a choice is made. This choice is then evaluated in the decision node. That's the whole purpose of a decision node. It's not an action itself. – qwerty_so Apr 04 '17 at 22:27

score 0 · Answer 2 · answered Apr 01 '17 at 18:53

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I assume you're asking if it's possible to loop from a decision back to itself. Doing so would create an infinite loop. The reason is that the guard condition would never have a chance to change, so the token would cycle forever.

answered Apr 01 '17 at 18:53

Jim L.

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Why wouldn't it have a chance to change? There can be an action that changes the condition, no? – Takichiii Apr 04 '17 at 22:24
If you add another action, you no longer have a loop from a decision back to itself! – Jim L. Apr 05 '17 at 05:15

UML Activity Diagram :loop on decision node

2 Answers2