[UML Forum] Activity Diagram: Different notations for parallelism and synchronisation?

[maurice_t]

Hello,

in activity diagrams I can use the fork and synchronisation symbol to
split up and rejoin threads. Often I see that to parallel transitions
lead directly into an action. As far as I know this is equivalent to a
synchronisation. Also it is possible in UML tools to start multiple
transitions from one action, but I never saw this in a diagram. Is
this a shorthand for a fork?

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[vincent...@atosorigin.com]

First of all, just to be sure that we talk about the same thing,
though we do not use the same language :
When you say "synchronisation symbol", you are talking about a Join
Node, right ?

On May 20, 12:52 am, maurice_t <maurice.huell...@googlemail.com>
wrote:

> Often I see that to parallel transitions
> lead directly into an action. As far as I know this is equivalent to a
> synchronisation. Also it is possible in UML tools to start multiple
> transitions from one action, but I never saw this in a diagram. Is
> this a shorthand for a fork?
>

Yes it is :

When several flows come into a same action, there is an implicit Join
node. Which means we wait for all flows before executing the action.
(see 12.3.2 Action > Semantics > [1] in UML Superstructure
Specification, V2.2)

When several flows go out of a same action, there is an implicit Fork
node. Which means we offer tokens to all outgoing flows, except if
this flow has a specific guard which prevent it. (see 12.3.2 Action >
Semantics > [4] in UML Superstructure Specification, V2.2)

[Maurice Huellein]

Thank you for your answer. Yes, i meant a join node. So in many cases you can just omit a fork/ join node,
like it could be done with this example:

http://www.tutorials.de/forum/attachments/sonstige-sprachen/27502d1167000571-27502attachment.jpg

So I am just wondering why the shorthand notation is not commonly used. Most times I see the explicit
use of the notation although it is not needed. But good to be sure now.

2010/5/20 vincent...@atosorigin.com <vincent...@atosorigin.com>