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Re: Same model for both Public and Private process ??

From: Ricky Ho <riho@cisco.com>
Date: Mon, 03 Feb 2003 11:21:41 -0800
Message-Id: <4.3.2.7.2.20030203103549.027f45d0@franklin.cisco.com>
To: Mayilraj Krishnan <mkrishna@cisco.com>, arkin@intalio.com
Cc: public-ws-chor@w3.org

Mayilraj, thanks for your response.  My comments are embedded

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
The external behavior can be modelled in both activity and transition 
diagram always.
(1) State Transition Diagram
Each action is taken when events are detected by the state machine. Action 
will get the inputs by the event.
Here emphasis given more to the states of objects and transitions of the 
states. In practice UML recommendation is
also to model the reactive objects(normally single)  by state transition.

<Ricky>
 From the perspective of "external behavior", I think the emphasis should 
be in "events", "transitions", "states".  I'm not sure about "action" 
because it seems to be exposing private implementation of how a party 
respond to an event.
</Ricky>

(2) Activity Diagram
Each action is taken when previous actions are completed or all the 
required inputs are available for the object.
Here emphasis given the order in which the actions are taken.

<Ricky>
Following my above argument that "action" is private implementation 
details, then the emphasis in "the order of actions taken" is certainly 
undesirable from a "public behavior" perspective.
</Ricky>

That is the reason I view better to model the external (abstract) behavior 
using activity diagram.
Notations:
Activity Diagram          State Transition
----------------------- ----------------------
Action          Simple State
Activity                State
fork/join               fork/join
transition              transition

<Ricky>
I have a different opinion.  It seems to me that an "ARC" in the state 
transition diagram should correspond to a "NODE" in the activity 
diagram.  On the other hand, an "NODE" in the state transition diagram 
should correspond to an "ARC" in the activity diagram.
</Ricky>

You can not define the swimlanes (does not have semantics in UML) in state 
transition
but the roles representation is clear using swimlanes and can be easily 
visualized in activity diagrams.

<Ricky>
I think it is easier to extend the "event definition" of the "state 
diagram".  E.g.  (Event is always "role X is sending a message M to role Y").
</Ricky>

I guess I'm talking about the opposite.  I think a "private process" is 
richer than a "public process".  By taking away the "process variables", 
"conditions", a "private process" will become a "public process".  Is that 
true ?

Here I agree with Asraf comment "The fine line between  public and private 
process  is computation intensive nature".
I think this computation intensive only you are calling richness. In that 
case yes, private process is richer than public process.
But if it is not computation intensive I don't know why we have to model 
the operation using activity or state transition
diagrams.
If you remove the states, actions, transitions from the state machines it 
becomes flowchart.

<Ricky>
I don't understand here.  What is left after removing states, actions, 
transitions from the state machines ?  How come it turn into a flow chart 
?  An example ??
</Ricky>

Best regards,
Ricky
Received on Monday, 3 February 2003 14:22:33 UTC

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