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#description

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.