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RE: targetResource wording

From: VAMBENEPE,WILLIAM (HP-Cupertino,ex1) <vbp@hp.com>
Date: Thu, 19 Jun 2003 17:17:08 -0400
Message-ID: <68157FD469848D45B9CBC2833AD5528002159483@xsun02.ptp.hp.com>
To: "'David Booth'" <dbooth@w3.org>, www-ws-desc@w3.org
Cc: Mark Baker <distobj@acm.org>, Sanjiva Weerawarana <sanjiva@watson.ibm.com>, "Champion, Mike" <Mike.Champion@SoftwareAG-USA.com>


+1. Excellent summary David.

William

> -----Original Message-----
> From: David Booth [mailto:dbooth@w3.org] 
> Sent: Thursday, June 19, 2003 12:14 PM
> To: www-ws-desc@w3.org
> Cc: Mark Baker; Sanjiva Weerawarana; Champion, Mike
> Subject: Re: targetResource wording
> 
> 
> 
> It looks to me like there is some misconception of what the 
> targetResource 
> means, partly (I think) because some of the statements in 
> this discussion 
> have been a little imprecise.
> 
> The targetResource attribute has nothing to do with describing a 
> service.  It is used to indicate a relationship *between* 
> services.  Its 
> purpose is to allow two WSDL <service> descriptions, d1 and 
> d2, to assert 
> that (behind the scenes) the services s1 and s2 that they 
> describe are 
> actually "manipulating" the same resource.  In other words, 
> if d1 and d2 
> both state "targetResource='u'", where u is some URI, then they have 
> asserted that s1 and s2 "manipulate" the resource r that is 
> identified by 
> URI u.
> 
> As we know from RFC2396[1], a resource can be anything -- a physical 
> object, an abstract concept -- anything.  So what does it 
> mean to say that 
> s1 and s2 "manipulate" the same resource r?  Without knowing 
> the semantics 
> of d1 and d2 you don't know.  That is not defined by the WSDL 1.2 
> specification.  (Nor should it be, IMO.)  Until you know the 
> semantics of 
> d1 and d2, the only concrete thing you can conclude is that 
> s1 and s2 are 
> somehow related to each other through r.
> 
> (Just in case there is confusion about this, the "targetResource='u'" 
> attribute is NOT asserting that s1 and s2 are the same 
> resource as each 
> other, nor is it asserting that s1 and s2 are the same resource as r.)
> 
> Does this vagueness present a problem?  No.  Different 
> applications will 
> know what they wish to do with this.  (The canonical example is a 
> printDocument service s1 and a managePrinter service s2, both 
> manipulating 
> the same physical printer r.)  The reason the WG described the 
> targetResource as "manipulating" the same resource was to give users 
> guidance about its intended use, even though the precise 
> meaning of the 
> word "manipulate" is impossible to nail down in this context.
> 
> Regarding the name "targetResource", u does identify a 
> resource, so the 
> "Resource" part of the name definitely is appropriate.  Furthermore, 
> proponents of the targetResource attribute like to think of r 
> as being the 
> ultimate "target" of interactions with s1 or s2; hence the name 
> "targetResource".
> 
> I hope this helps to clarify the situation.
> 
> 
> 1. RFC2396: http://www.ietf.org/rfc/rfc2396.txt
> 
> 
> -- 
> David Booth
> W3C Fellow / Hewlett-Packard
> Telephone: +1.617.253.1273
> 
Received on Thursday, 19 June 2003 17:17:11 GMT

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