Connector control nodes?

[ericf]

UML 2.0 defines a number of "control nodes" that can be used in activity diagrams, but I don't see how to do some of them with EA.

Specifically, the following is in Chapter 13 of "UML 2.0 for Dummies" (a pretty good book, despite the series title):

"Control node: You use control nodes to guide the flow of control [...] through a group of activities and actions.  Control nodes come in a variety of forms. [... They] are as follows:

[...]

* Connector: If you run out of room on your diagram and you need to continue the flow of control to another page, use a connector -- a small circle with a label inside.  The connector indicates that the flow picks up at another location in the diagram or on another page where you find a connector with the same label."

EA has "Initial" nodes which are *one* kind of control node, but I don't see anything that meets the above description.  

Any pointers to what I'm missing?

[sargasso]

Hi Eric,

I thought that's what the "Synch" nodes were for - maybe I'm wrong?

Bruce

[ericf]

One of our guys thought so too, but that's not what the EA documentation suggests (to me):

"A synch state is useful for indicating that concurrent paths of a state machine will be synchronized. After bringing the paths to a synch state, the emerging transition will indicate unison."

So "synch" nodes are more for concurrency scenarios than for showing connections across models.  Another colleague described the intent of connectors as being like Star Trek wormholes....

[KP]

Try this...

Draw a control flow between two activities or actions. Right-click on the control flow and select "Toggle Line Point at Cursor". Repeat. You will now have a control flow made up of three segments. Right-click on the middle segment and select "Suppress Line Segment". Give the control flow a name and it will appear in the segment ends.

Is this what you were after?

[ericf]

That's it!  Thanks so much!!!

[ericf]

PS -- will this work across EA diagrams?  Could I break a large model up into two diagrams and have control flow from an activity in one diagram to another via one of these named connectors?  What you've described works great *within* a diagram -- just like to understand how to use it *across* diagrams.

[thomaskilian]

EA is full of wonders. I can't imagine how many features there are that I still haven't explored  

[KP]

PS -- will this work across EA diagrams?  Could I break a large model up into two diagrams and have control flow from an activity in one diagram to another via one of these named connectors?  What you've described works great *within* a diagram -- just like to understand how to use it *across* diagrams.

I just knew you were going to ask that! I've had a look through the UML2.0 specification, and found this: "Every connector with a given label must be paired with exactly one other with the same label on the same activity diagram." which precludes using this mechanism for off-page connectors.

So I'm not really sure what the best solution is. Maybe you can borrow from Interaction Overview diagrams and drag the referenced diagram across onto the current diagram and then put a control flow going to it? A useful side-effect of this approach is that it gives you a hyperlink to the referenced diagram.

[sargasso]

  I suppose this raises the metaphysical issue of just what constitutes a "diagram"?  

To be serious, what you have both found is a hassle, regardless of whether the intent is to provide a connector that is related

* on-page (obviously in the same diagram, and inserted to simplify crossovers)

* off-page on a multipage diagram ( inserted to assist the reader in tracing across page breaks)

* between diagrams ( which I still maintain is a valid use of "synch" regardless of whether they are activity or state diagrams)

It seems absolutely crazy to me that OMG have completely obfuscated one of the simplest elements of a flowchart (the "off-page conector") The use of a circle with a label in it has been around since Grace Hopper was a little girl.  It is understandable, commonly used etc etc ...

so I say  SCR ::)W 'EM - lets use the synch element.


B