Re: WSDL Import/Include Locations

The specification currently discusses the problem of circular imports 
and includes, which may address these questions (basically, it says 
that a processor *must* recognize when an import or include, even if 
nested, has been encountered before, and should not go into an infinite 
importation/inclusion loop).

Import and include are defined to have roughly the same semantic as in 
W3C XML Schema, with restrictions (no chameleons).  This has the 
advantage of providing readers and implementors of the specification 
with an external model, one which is hopefully well known.  Major 
changes to those semantics ought to have benefits at least equal to the 
expected familiarity, since they would presumably trade off the benefit 
of familiarity for the benefits introduced.

Given the existence of cataloging/registry/resolution APIs and software 
modules, I'm not certain that adding additional optional locations 
meets that standard of equal benefit.  However, I can be convinced, if 
it truly is the case that no one (else, that is) uses moderately 
sophisticated resolution/cataloging technologies.

On Jan 22, 2004, at 6:09 PM, Yaron Goland wrote:

> Both WSDL import and include only allow for a single location to be
> specified. Given the unreliable nature of the Internet would it not be
> appropriate to allow for more than one location to be specified?
> Given the permissive semantics of include it would be tempting to 
> specify
> multiple includes, all pointing to the same file but at different 
> locations
> as a way to make the WSDL definition more robust in the face of network
> failures. However this would needlessly waste system resources making
> unnecessary file requests. If the WSDL processor knows that a set of 
> URIs
> are equivalent then it need only make requests until it finds a URI 
> that
> works.
> In the case of import the specification doesn't actually define what 
> happens
> if someone writes two imports for an identical namespace. Although some
> limited definition redundancy is supported by the spec the support 
> would not
> appear to be robust enough to support importing the same WSDL 
> definition
> twice. Therefore putting in two imports as a way to provide redundant
> locations would appear illegal.
> But this begs the question - Is it illegal to specify two imports for 
> the
> same namespace? If so, shouldn't this be explicitly stated in the spec?
> What is the required behavior if it is impossible to successfully
> import/include an identified document? If this an unrecoverable error 
> that
> requires that the WSDL be rejected for processing? If so, then 
> shouldn't the
> spec explicitly state this?
> 	Thanks,
> 		Yaron

Received on Friday, 23 January 2004 11:59:05 UTC