Concept of "Is Return" message in sequence diagram

[Silvester Rößner]

Hello everyone,

I have a problem to understand the concept of the checkbox "Is Return" of dialog "Message Property" on sequence diagrams.

In my opinion I should be able to select an operation from the called object as message if I check "Is Return". But I can only select an operation from the caller.

Another possibility would be that EA reverts the arrow if I select "Is Return".

But neither is the case.

Am I missing the point here?


In more detail:

- I have two Objects: A and B
- Object B has an operation: calculate(float, float): float
- I draw a message from A to B and select this operation as message
- EA shows the signature of this message.

Now I want to model the return value explicitly

- I draw a message from B to A
- and tick "Is Return".
  But I can't select an operation from Object B.
  So I would have to add the same operation to A
  in order to show the correct signature.
  But this is semantically wrong.
  A doesn't have this operation at all - it uses it.

or

- I draw a message from A to B
- and select the operation from B
- EA shows the correct signature -
  but the arrow points in the wrong direction
  and the complete diagram semantics is wrong now.

[Kevin G. Watson]

Hi'ya....  There's a hint of something assumed; Settings | Tools | Options ... Sequence in the option tree... 'Assume message returns' just above 'auto garbidge collection'....

All them auto draw dotted lines whizzing about, really made seeing the actual messages being sent obscure.  Not the idea at all.... so

Graphic to follow.... but just do ya call;  then draw another line and just click the 'Is return'  will simulate the effect I think you are seeking.

I haven't tried it, but just filling out the vairable thingie thats the target of your return value, I think it's called assign.... of the dotted line symbol thingie.... you probably need to have an attribute all ready defined ( declared.... how you show placeholders for yet to be used object instance fields? (UML Class Property - formally Attributes)... yet to be used message ( the one with all the cost )....

If your sending a  synchronious message, then the line has a top and bottom ... you send on the top and return on the mono-rail.  The focus of control does not continue ( it an't there it's bouncing around at obB).

The folks who argued that all them return messages... they was a little confussed about asynchronious messaging ( was it a signal ) .

Kevin [smiley=2vrolijk_08.gif]

[Kevin G. Watson]

Promised picture

 [smiley=grin.gif] Kevin

[Kevin G. Watson]

Just thought... would a Jing presentation help?

Kevin