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Subject: RE: [wsbpel] Issue - 88 - Import Errata


Hi Paco,

I agree with you that the WSDL 1.1 wording is ambiguous. The phrase "WSDL allows associating a namespace with a document location using an import statement" seems to imply that the whole purpose of the import is to establish the document location. Fortunately WSDL 1.2 is much more clear in this respect, by stating that the namespace attribute is required and the location attribute is optional. So the import is meaningful whether a file location is specified or not.

Regarding the import itself being optional, WSDL 1.2 is again much more clear in this respect. It says "Using the import construct is a necessary condition for making components from another namespace available to a WSDL description. That is, a WSDL description cannot refer to components in a namespace other that the target namespace unless an import statement for that namespace is present".

We don't necessarily need to follow the Schema and WSDL 1.2 directions, but it might be a good idea to conform and say that our import is also required.

Ugo

> -----Original Message-----
> From: Francisco Curbera [mailto:curbera@us.ibm.com]
> Sent: Thursday, December 04, 2003 8:33 PM
> To: Ugo Corda
> Cc: wsbpel@lists.oasis-open.org
> Subject: RE: [wsbpel] Issue - 88 - Import Errata
> 
> 
> 
> 
> 
> 
> Hi Ugo,
> 
> I think you have spotted an important difference in approach 
> that had not
> surfaced before.  I think this relates to whether we make 
> imports required
> or not - and what "honor" means.
> 
> Nothing in WSDL 1.1 says that imports are required (as they are for
> instance in XSD). The only statement made in WSDL 1.1 is that import
> "allows associating a namespace with a location". So the notion of
> "honoring" import is a very vague one: if the association is not used
> (because we cached the file or whatever) then the import is 
> ignored, but
> this does not mean that definitions from that namespace (or 
> from namespaces
> not imported) are not processed. External definitions are 
> referenced using
> qualified names, and XML namespace mechanisms are there to 
> allow unique
> identification - how they are found and retrieved is up to 
> each processing
> environment.  Import statements just make life a little 
> easier by providing
> an associated location.
> 
> XML Schema does require an import clause for every external namespace
> containing definitions. Maybe it then makes more sense to talk about
> "honoring" an import because a processor can rely on 
> inspecting imports
> clauses to preprocess all external definitions it depends on, 
> instead of
> relying on XML namespace mechanisms.
> 
> So I would say that there is a legitimate issue here, but that it goes
> beyond the strict wording that you mention. I think we need  
> to address of
> whether imports are required for every external definition used by the
> process. I can imagine there will be different opinions.
> 
> Paco
> 
> 
> 
> 
>                                                               
>                                                               
>             
>                       "Ugo Corda"                             
>                                                               
>             
>                       <UCorda@SeeBeyond        To:       
> <wsbpel@lists.oasis-open.org>                                 
>                  
>                       .com>                    cc:            
>                                                               
>             
>                                                Subject:  RE: 
> [wsbpel] Issue - 88 - Import Errata                           
>              
>                       12/03/2003 07:08                        
>                                                               
>             
>                       PM                                      
>                                                               
>             
>                                                               
>                                                               
>             
> 
> 
> 
> 
> > What happens if an engine chooses not to honor the import?
> > The current text of the BPEL spec states that the BPEL engine
> > is not required to import the files it is pointed at.
> 
>  I don't think that not importing the files necessarily 
> implies that the
> import is not honored.
> 
> The original statement in the resolution of Issue 7 was:
> 
> "A <bpel:import> location element will be interpreted as a 
> hint for BPEL
> processors. In particular, processors are not required to retrieve the
> imported document from the specified location".
> 
> So it only says that the location information is a hint (but 
> the import
> statement could still be satisfied by other means).
> 
> The statement appearing in the latest draft is more ambiguous:
> 
> "The presence of an <import> element should be interpreted as 
> a hint to the
> BPEL4WS processor. In particular, processors are not required 
> to retrieve
> the imported document from the location specified on the 
> <import> element".
> 
> Now it is saying that the <import> element itself is a hint. 
> Not sure what
> exactly that means.
> 
> Ugo
> 
> 
> 
> 


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