Messages

31

Uml Process / Re: UML relationship between cluster and server

« on: February 27, 2013, 02:17:19 am »

The three of them (association, aggregation, and composition) are valid, and the subtleties are a good topic for a pub conversation :-)

I use this rule of thumb:

1) If the association is between parts and a whole, I tend to use aggregation or composition, instead of simple association.

2) If, in the view you are trying to depict, a part's existence has no sense outside the whole, I tend to use composition, instead of aggregation.

3) If the part may be a part of another whole, you can use composition only for one of those relationships; for the other ones, you must use aggregation.

In your case, if your server will always be part of one and only one cluster, I'd use composition.

32

Uml Process / Re: Squence Diagrams with embedded Components

« on: February 13, 2013, 06:39:47 am »

Wow, I missed that one. Time to update my sequence diagrams :-)
Thanks!

33

Uml Process / Re: Squence Diagrams with embedded Components

« on: February 12, 2013, 12:42:58 am »

This feature seems quite useful, but it is not standard UML, is it?

34

Uml Process / Re: Merge node missing?

« on: July 27, 2012, 08:46:25 pm »

Enterprise Architect 9.3.933 (Build: 633) - Unicode.
System Engineering Edition

Project --> New Diagram --> UML Behavioral --> Activity
In the tools panels (left): Activity Patterns: Basic Activity

Well, if nobody here sees this as an error, that means that nobody here sees this as an error

35

Uml Process / Re: Merge node missing?

« on: July 27, 2012, 06:05:54 pm »

I agree that, normally, there is no real ambiguity if you look at the whole diagram, but if you focus only in the area containing the 'future' action (which may be far away from the decision node) you can make wrong interpretations, especially if there are several decision, merge, join, and fork nodes around.

I am more concerned here with (syntax) correctness. I have dared downloading and reading the standard  , and I've found the following (in formal/11-08-06_supra):

12.3.2 Action
[...]
An action may have sets of incoming and outgoing activity edges that specify control flow and data flow from and to other nodes. An action will not begin execution until all of its input conditions are satisfied. The completion of the execution of an action may enable the execution of a set of successor nodes and actions that take their inputs from the outputs of the action.
[...]
Except where noted, an action can only begin execution when it has been offered control tokens on all incoming control flows and all its input pins have been offered object tokens sufficient for their multiplicity.
[...]
An action execution is created when all its object flow and control flow prerequisites have been satisfied (implicit join). Exceptions to this are listed below.
[...]
See ValuePin and Parameter for exceptions to rule for starting action execution.
[...]
12.3.50 ValuePin
[...]
ValuePins provide values to their actions, but only when the actions are otherwise enabled. If an action has no incoming edges or other way to start execution, a value pin will not start the execution by itself or collect tokens waiting for execution to start. When the action is enabled by other means, the value specification of the value pin is evaluated and the result provided as input to the action, which begins execution. This is an exception to the normal token flow semantics of activities.
[...]
12.3.41 Parameter
[...]
All required non-stream inputs must arrive for the behavior to be invoked. If there are only required stream inputs, then at least one must arrive for the behavior to be invoked.

If I have interpreted the standard correctly, the exceptions do not apply to the general cases I have presented. So, I think that the "Basic activity" pattern in EA 9.3 has an error.

36

Uml Process / Merge node missing?

« on: July 27, 2012, 03:27:06 am »

I have always thought that, when you have a branch (decision node) in an activity diagram, and the flows reunite in a future action, you must use a merge node before that future action. Otherwise, that future action will wait (by default) for a token on each of the arriving edges, an event that will never happen. In other words, two edges arriving at one action are equivalent to an implicit join, not an implicit merge.

But in the "Activity Pattern" named "Basic Activity" provided in EA 9.3, you can find this very error! Who is mistaken, me or "EA 9.3"?

You can see the same (presumed) error in http://commons.wikimedia.org/wiki/File:Activity_Diagram_1.jpg (in "Attivita 5") or in http://upload.wikimedia.org/wikipedia/commons/e/e7/Activity_conducting.svg (in "Explain problem").

37

Automation Interface, Add-Ins and Tools / UML profile for safety analysis

« on: September 15, 2010, 10:33:00 pm »

Has anyone developed a profile for performing safety analysis, similar to that developed by Bruce Douglass for Rhapsody? (see http://www.ibm.com/common/ssi/fcgi-bin/ssialias?infotype=SA&subtype=WH&appname=SWGE_RA_SY_USEN&htmlfid=RAW14124USEN&attachment=RAW14124USEN.PDF)

I'm specially interested in FTA.

And is (s)he willing to share it?  

38

Automation Interface, Add-Ins and Tools / Re: MDG's SysML Add-In

« on: September 15, 2010, 10:13:30 pm »

I'm using EA Systems Engineering Edition (which implements SysML 1.1 internally, no with add-ins) and it seems rather SysML compliant.