RE: Why do we have a component model?

Arthur, 
 
My understanding is that Z notation was introduced after the last call
not as a result of some last call requirement, but to simplify for the
test suite and illustrate the inconsistencies based on formal
verification. From this perspective, I personally do not regard it as a
must have for the spec, but a nice to have. This has been my consistent
view about the Z notation. Sorry :-(
 
The current discussion about the component model appears to be about
whether the component model is necessary and whether makes it
easier/harder to understand the semantics of the spec. On top of this
discussion, which is separate than Z notation, we have Z notation
sprinkled in the specification. A reader is somewhat overwhelmed by the
introduction of the mathematical formulae just looking at the spec. I
noticed that it was even hard for the wg to search for sections during
the f2f meeting skipping over sections that contained Z notation. 
 
I am not sure how many people in the wg are even using the Z notation
themselves (I don't), but we would expecting developers to follow to
spec and not be discouraged to understand it. I personally do not want
to read yet another xml.com articles perhaps titled "WSDL 2.0 spec gave
me the ZZzz".  ;-) I am wondering whether we could actually utilize the
Z notation in an adjunct document, but not in the specification itself.
Just a thought. 
 
After all WS-I used plain English...
 
--umit

 

  _____  

From: Arthur Ryman [mailto:ryman@ca.ibm.com] 
Sent: Tuesday, Mar 08, 2005 8:15 AM
To: Sanjiva Weerawarana
Cc: Anish.Karmarkar@oracle.com; bparsia@isr.umd.edu;
jean-jacques.moreau@crf.canon.fr; paul.downey@bt.com; Yalcinalp, Umit;
www-ws-desc@w3.org; www-ws-desc-request@w3.org
Subject: Re: Why do we have a component model?



Sanjiva, 

I understand your reservations about Z Notation and agree it would be
better if the spec didn't need it. However, I think it does. I'd like to
clarify the purpose of the Z Notation. 

The WSDL 1.1 was great in that it was short and got the Web services
wave going, but it did have some problems. 

My experience as a tool implementer working with WSDL 1.1 pointed out
how easy it is for people to misinterpret a spec. We ran into many
problems where one team generated WSDL 1.1 that they thought was valid,
only to find that other tools could not process it. This was an
industry-wide problem. It led to the creation of WS-I. The WS-I BP 1.0
[1] contains around 89 clarifications to the WSDL 1.1 spec. I don't
think any of us wants to see that repeated for WSDL 2.0. 

Z Notation is simply a QA technique to expose problems in the spec, and
I think it has already found quite a few of them. I am confident that if
we produce a spec that has a consistent Z description, then we will have
far fewer problems in implementations. 

[1]
http://www.ws-i.org/Profiles/BasicProfile-1.0-2004-04-16.html#descriptio
n 

Arthur Ryman,
Rational Desktop Tools Development

phone: +1-905-413-3077, TL 969-3077
assistant: +1-905-413-2411, TL 969-2411
fax: +1-905-413-4920, TL 969-4920
mobile: +1-416-939-5063, text: 4169395063@fido.ca
intranet: http://labweb.torolab.ibm.com/DRY6/ 



"Sanjiva Weerawarana" <sanjiva@watson.ibm.com> 
Sent by: www-ws-desc-request@w3.org 


03/08/2005 10:25 AM 


To
<paul.downey@bt.com>, <umit.yalcinalp@sap.com>,
<jean-jacques.moreau@crf.canon.fr>, <bparsia@isr.umd.edu> 

cc
<Anish.Karmarkar@oracle.com>, <www-ws-desc@w3.org> 

Subject
Re: Why do we have a component model?

	





Hi Paul,

> seems to me that we spend most of our time trying to fix bugs in the
component
> model, in particular the area of composition.

Can you back that up with real info please? I'd be impressed if you
could
indeed
show that we spend most of our time on component model problems. IIRC
very few of our LC comments are about the component model *per se*; of
course they have component model implications as that's how WSDL is
defined.

If you want to claim that the Z notation stuff has brought up lots of
problems,
well, then the problem is that we decided to retrofit an abstraction on
top
of
an abstraction.. not the other way around. Record will show that I was
against
doing the Z notation from day one.

>The engineer in me wants to find a
> simpler solution rather than continue to add more sticky tape and
chewing
gum.

Well so do I. I hardly find this particular assault on the component
model a
good reason to throw it all away and start with a new mess.

As was re-asserted at the F2F, the spec as its written was explicitely
not
written for end-users (read as people implementing services) but rather
for
implementors (read as people implementing WSDL tools/runtimes, SOAP
stacks, etc.). The component model provides a degree of rigour to that;
so
read with the runtime and tooling engineer in you rather than the Web
service
author engineer in you. I know you have at least two engineers in you!
;-)

> i'm drawn to the idea of spec which is focused on the document rather
than
the
> processing model, even if that meant losing import (but keeping a
lexical
include).

Been there, done that. Again, with all due respect, you need to read the
archives and see how we got here. I personally was against adding
import/
include but lost. Such is the world of design by committee; somethings
you
like, some that you don't. The other option is design in a closed room;
would
you prefer that (esp. if you didn't happen to be in the room)?

Sanjiva.