RE: Proposal to Simplify the UML

OK, if you think cardinalities are really important, I think you should
be a lot more careful about whether you use * or 1,..  It appears to me,
and I think that Chris Ferris is agreeing, that 1,.. is actually correct
in a bunch of places you have *.  I tried to point out a few by asking
questions based on the existing *'s, but I did not try to do so
exhaustively.  You have a lot of *'s and I really suspect that a large
number of them should be 1,..  If one actually is making the distinction
they are not at all the same -- one implies that a spec MUST require
that something is there (generally if something else is there), the
other implies that a spec MUST allow something to be missing (even if
something else is there).  Both can be non-trivial requirements.
 
Yes, my suggestion below is indeed counter to the previous one, which
was to use the terms consistently as per standard definition.  I suggest
below that we define our own, non-standard usage that allows a looser
cardinality than in the standard but also supports the more restrictive
terms when we are sure that we mean them.
 
I still think that putting in all these cardinalities is going to get us
involved in a bunch of discussions that are more detailed than they need
to be, but it seems to me that this is certainly a view upon which
reasonable people can differ.
 
-----Original Message-----
From: Martin Chapman [mailto:martin.chapman@oracle.com] 
Sent: Friday, June 13, 2003 11:19 AM
To: Cutler, Roger (RogerCutler); www-ws-arch@w3.org
Subject: RE: Proposal to Simplify the UML


 

	-----Original Message-----
	From: www-ws-arch-request@w3.org
[mailto:www-ws-arch-request@w3.org]On Behalf Of Cutler, Roger
(RogerCutler)
	Sent: Thursday, June 12, 2003 6:02 PM
	To: www-ws-arch@w3.org
	Subject: Proposal to Simplify the UML
	
	

	In accordance with the expression on the concall today that we
should not incorporate excessive detail into the UML, I would like to
propose the following guidelines (which I am perfectly willing to admit
are phrased loosely):

	1 - Cardinalities should be omitted unless they are really
obvious (and contribute to understanding the sense of what is going on
-- often where there is a "1")  or where they are really non-trivial and
we have discussed and agreed on them (as one hopes will happen with the
number of receivers or paths). 

	The tool I use doesn't give me much choice in eliminating some
of the "1", which I agree is redundant. If someone elee wishes to redraw
in another tool to eliminate the "1"s then they are welcome to do that, 

	2 - We adopt a convention, for the purposes of this document
only and documented prominently (since it is nonstandard), that "*"
means "0 or more OR 1 or more, we are not specifying which".  When we
really know which we mean and want to make a point of it, we always use
"0,.." or "1,..". 

	What is not standard? * means 0 or more. This is now counter to
the changes you suggested yestereday (to elimitae 0..*) 

	There are two reasons for this.  To avoid: 

	1 - Endless fruitless arguments about arcane issues (like
whether a message exists if it has not been read ... does a sender exist
if he has not sent ... does a ... uh, SLAP! ... gotta stop ...) 

	Why is this fruitless. It helps to fully understand what is
going on. 

	2 - The possibility of people down the line saying things like: 
	   A:"The WSA DEMANDS that if a spec will allow a FOO it must in
all cases tell you how to have a BAR";   
	   B:"The WSA DEMANDS that the spec MUST be capable of having a
MEAL without a BARF".  

	and the problem with this is?

	  
	Well, maybe in the latter case it's reasonable, but surely you
see what I'm talking about.  Both cases are, in fact, silly if we never
really thought about how FOO's and MEAL's relate to BAR's and BARF's. 

	The point of doing this execrise is exactly to consider all such
issues. Its not just about pretty pictures. 

	Let's keep the detail down to things we really mean.  

	So after we finish this current excercise of modelling soap, we
need to decuide what detail to elimiate for our doc.

	I suggest that cardinalities are imporant and we should be
looking to supress some of the boxes and relationships.