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I've found an exercise online that shows an activity diagram with some boxes:

enter image description here

And then it asks the following questions:

  1. The diagram represents 2 actors each represented by a partition" Possible Answers: "False" "True"

  2. This diagram represents the activities of how many use cases?" Possible Answers: "6" "1" "2" "none"

  3. This diagram has 2 conditional tests" Possible Answers: "False" "True"

So with this question, I'm wondering if it can represent a use case, and if it does have actors

Christophe
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Synthy Jericho
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1 Answers1

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  1. A partition does not necessarily correspond to actors, and every actor does not necessarily correspond to a partition. Moreover Student could correspond to the behavior of a Machine learning component internal to a larger system. So this question cannot be answered with certainty.

    However, assuming that this activity diagram was designed on the base of a use-case and that we can trust the names of the reagion, there would be only one actor: Student, since System would be the subject.

  2. Use cases correspond to objectives of the actors and not actions. Moreover a sequence of actions could correspond to a scenario with included or extend use-case and unclear boundaries. Again, we cannot answer this question for sure.

    However, considering that use-cases should be independent and not sequenced, we see that there is only one set of connected activities and one initial node. So if it represents use cases, it would be only 1.

  3. This diagram has 2 decision nodes that can each make choices. So the two "conditional tests" do not seem wrong, but it's not UML terminology.

As a side remark, unrelated to your question: The “Select Billets…” activity will never start, because activity diagrams are not flowcharts. Two incoming flows on an activity require both flows to deliver a token before the activity can start. But the rest of the diagram only allows a token to appear on one of the edge, thus leading to a never-ending wait. More explanations here.

Christophe
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    The 2nd action top left will never start. You might explain why... – qwerty_so Jul 01 '21 at 08:39
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    @qwerty_so Indeed. I must say that two outgoing edges are in my mind clearly an implicit fork; but for two incoming flows I always hesitate. Personally I prefer to avoid multiple incoming/outgoing flows and make fork/joins and merges explicit. I edited and added a link to your perfect explanations ;-) – Christophe Jul 01 '21 at 17:04