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Subject: RE: [wsbpel] Issue - 46 - Namespace for the document fragment representing a part


Thanks for chiming in.

I believe, for clarity, we need more examples.  It may be clear to the
experts how a bpel engine should reconstitute a document fragment when
it is transmitted in any binding.  However I am not sure it is clear to
everyone else.  Let's make sure it is clear so that the queries that
user's write will not result in failures based on the engine they are
using or the partner's binding they are dealing with.  IMO we need to
spell it out with examples or we will end up with problems.  There are
too few examples of query usage given how heavily people will rely on
The other issue with these document fragments being reconstituted from
any binding is that they can be modified by assign activities.  If we
aren't careful it will be difficult to validate these modified

In summary if the only outcome of this issue is that we add a few more
examples. And state precisely what a part/query context is (for both
part as type and part as element) so that it is unambiguous under any
binding (as bpel is binding independent).  Plus as a real nice to have
make sure that the resulting parts can be validated even after use
within a <to> assign.  Then it was worth raising the issue.

-----Original Message-----
From: Sanjiva Weerawarana [mailto:sanjiva@watson.ibm.com] 
Sent: Thursday, August 07, 2003 3:10 PM
To: chris.keller@active-endpoints.com; 'Ugo Corda';
Subject: Re: [wsbpel] Issue - 46 - Namespace for the document fragment
representing a part

As the culprit behind the XPath stuff in BPEL 1.1, I'd like to weigh
in on this. I was also on the XSLT WG where XPath 1.0 was defined.

"Chris Keller" <chris.keller@active-endpoints.com> writes:
> Sorry if the wording of my replies misled you.  My Issue is not really
> about the part as type and property alias queries, but also XPath 1.0
> vs. XPath 2.0 and the queries within bpel assignments and expressions.
> Even if we assume no namespaces in the document fragment under the
> as type case (which we should think hard about as validation would be
> issue), many of the messages would most definitely contain namespaces
> and as such require qualification in XPath 1.0. 

XPath 1.0 does not require qualification unless the element/attribute
itself is qualified. How else could it work??

What's the validation for unqualified stuff? I don't know of any myself.

So as Ugo said, if the schema for the complex type that part/@type
is referring to has qualified stuff, then stuff that follows
would indeed be qualified. If not it would not be. That's it.

Since we're still dealing with XPath 1.0 let's just focus on that and
not worry about what XPath 2.0 does or says. In particular, I'm not
qualified to debate that as I left the WG and haven't had the time
to follow the specs. I'm sure there are more expert people here who
can comment.

W.r.t. the general issue of what namespaces are in scope for an XPath
expression, XPath defines a notion of a context. So when evaluating
an XPath expression the namespaces defined by the context are assumed
to apply to the XPath expression as XPath itself has no way to define
namespaces. In particular, in BPEL when you say
say, the "bpel" prefix is resolved w.r.t. the namespaces visible on 
the element which contains an attribute whose value this expression is.

So I don't think there is any issue whatsoever w.r.t. the namespaces 
of part names or any other name used in any XPath expression in BPEL.
I'm not sure whether the spec clearly says how the XPath context should
be computed (IIRC something was added to clarify that) but there's 
only one meaningful way to do it (see above paragraph) IMO.



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