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RE: WSDL Import/Include Locations

From: Martin Gudgin <mgudgin@microsoft.com>
Date: Mon, 15 Mar 2004 01:37:50 -0800
Message-ID: <DD35CC66F54D8248B6E04232892B63380179F756@RED-MSG-43.redmond.corp.microsoft.com>
To: <ygoland@bea.com>
Cc: <paul.downey@bt.com>, <ryman@ca.ibm.com>, <www-ws-desc@w3.org>

Yaron,

I think it's OK for a WSDL processor to process imports
opportunistically. That is, not resolve any imports until it sees a
reference to a component in a given namespace, then process imports in
order until it finds that component. And so on.

Gudge

> -----Original Message-----
> From: Yaron Y. Goland [mailto:ygoland@bea.com] 
> Sent: 12 March 2004 19:52
> To: Martin Gudgin
> Cc: paul.downey@bt.com; ryman@ca.ibm.com; www-ws-desc@w3.org
> Subject: Re: WSDL Import/Include Locations
> 
> Although I now believe I understand the distinction I believe 
> this is something subtle enough to deserve a specific call 
> out in part 1.
> 
> Section 4.2 current contains the sentence "Directly imported 
> means that component importation is not transitive; 
> components imported by one of the imported documents are not 
> available to the original importing document unless the are 
> imported directly by that document."
> 
> I would propose inserting an additional sentence after this 
> one that reads "Note, however, that if a directly imported 
> document includes another document then the components in the 
> included document are available to the original importing document."
> 
> This then brings up another scenario that I'm not even sure is legal. 
> Imagine I have a WSDL namespace FOO and two files, FileA and 
> FileB that both define components in namespace FOO. The two 
> files do not define any common components and the two files 
> do not include each other. In other words, each file is 
> completely stand alone. In that case if a WSDL for namespace 
> BAR should have:
> <import namespace="f:oo" location="http://example.com/fileA"/>
> <import namespace="f:oo" location="http://example.com/fileB"/>
> 
> And if the WSDL should optimize by only successfully 
> downloading one of the two links then components needed by 
> WSDL BAR would not be downloaded.
> 
> This scenario presumes however that it is legal to have two 
> completely independent files defining non-overlapping 
> components in the same namespace that do not reference each 
> other. Is that legal?
> 
> 	Thanks,
> 
> 		Yaron
> 
> Martin Gudgin wrote:
> 
> > If A includes B then when C imports A all the constructs in A and B 
> > are visible to C. The text you refer to in Section 4.2 is about 
> > components that A *imports* not components that A *includes*
> > 
> > Gudge
> > 
> >  > -----Original Message-----
> >  > From: Yaron Y. Goland [mailto:ygoland@bea.com]  > Sent: 12 March 
> > 2004 00:28  > To: Martin Gudgin  > Cc: paul.downey@bt.com; 
> > ryman@ca.ibm.com; www-ws-desc@w3.org  > Subject: Re: WSDL 
> > Import/Include Locations  >  > Let's say that I have a WSDL 
> namespace 
> > FOO that is defined by  > two different files, A & B. File 
> A includes 
> > File B.
> >  >
> >  > I now want to define a WSDL namespace BAR and I want to use  > 
> > components that are defined in namespace FOO. One could  > 
> imagine an 
> > import statement of the form:
> >  > <import namespace="f:oo" location="http://example.com/fileA"/>
> >  >
> >  > However it turns out that one of the components I want to  > 
> > directly reference is defined in file B. Per section 4.2 in 
>  > part 1 
> > I can't directly reference any components in file B  > 
> unless I import 
> > it. So now the import section will have:
> >  > <import namespace="f:oo" location="http://example.com/fileA"/>
> >  > <import namespace="f:oo" location="http://example.com/fileB"/>
> >  >
> >  > Gudge, if I understood your previous point you suggested 
> that  > if 
> > one had multiple imports for the same namespace then one  > 
> was free 
> > to assume that they all point to the same infoset  > content and so 
> > one only needed to download one of the links,  > thus 
> neatly solving 
> > my concerns about redundancy and performance.
> >  >
> >  > But in this case that assumption doesn't appear safe. If the  > 
> > WSDL system only imported one of the two links from 
> namespace  > FOO 
> > then the WSDL definition would miss referenced components  
> > and fail.
> >  >
> >  > Did I miss something?
> >  >
> >  >       Thanks,
> >  >               Yaron
> >  >
> >  > paul.downey@bt.com wrote:
> >  >
> >  > > Yaron wrote:
> >  > >
> >  > >  > One of the most common ways to deal with 
> unreliability is to  
> > >  > > make information available at distinct locations. The  > 
> > advantage  > of  > > making data available at distinct locations is 
> > that not  > only  > does  > > it provide reliability in the face of 
> > endpoint failures but  >  > it also  > > provides 
> reliability in the 
> > face of network failures.
> >  > >
> >  > >
> >  > > Actually something that has always bothered me about 
> the /list/ 
> > of  > > locations in WSDL and Schema: if a list is essential for 
> > resilience  > > then why don't other languages such as HTML have a 
> > list of  > URIs in <a  > > href='...' etc ?
> >  > >
> >  > > My most common use for the location /list/ has been to 
> put  > a 
> > relative  > > URI followed by an absolute URI so that a the same 
> > schema  > may be used  > > stand alone on my laptop before being 
> > deployed on Web  > server elsewhere.
> >  > >
> >  > > Also I have a competing use-case against multiple locations:
> >  > >
> >  > > Before signing-off a Web service we test and validate 
> the service  
> > > > using a captured WSDL saved in our configuration 
> management system.
> >  > > This captured WSDL must be stand-alone since the WSDL  > 
> > published by the  > > service may later change. It's also not 
> > acceptable to store a  > > serialisation of the infoset 
> since this is 
> > different to the actual  > > published documents, invalidating any 
> > regression testing.
> >  > >
> >  > > So we need to not only store the root document but any 
>  > other 
> > documents  > > referenced and in a way that emulates how a 
> consumer of 
> > the actual  > > service would have worked.
> >  > >
> >  > > Here the redundancy lists only exasperates this difficulty  > 
> > since it is  > > possible for two test runs to be presented 
> with two  
> > > different sets of  > > documents.
> >  > >
> >  > > So a single URI in the location and having some  > 
> environmental 
> > change  > > to subvert the processor (a 'PATH' variable) 
> would be  > 
> > preferable here  > > rather than having to edit the WSDL 
> document and 
> > invalidate our  > > regression tests.
> >  > >
> >  > > Just another reason why concentrating on what is a 
> valid  > WSDL 
> > document  > > rather than the behaviour of a WSDL 
> processors is very 
> > useful.
> >  > >
> >  > > Paul
> >  > >
> >  > > --
> >  > > Paul Sumner Downey
> >  > > Web Services Integration
> >  > > BT Exact
> >  > >
> >  > >
> >  >
> > 
> 
Received on Monday, 15 March 2004 04:38:42 GMT

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