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Subject: RE: [wsn] AI from telecon 10/11
- From: Steve Graham <sggraham@us.ibm.com>
- To: Susan Malaika <malaika@us.ibm.com>
- Date: Mon, 18 Oct 2004 08:36:58 -0400
Susan:
It is my understanding that there are
intermediaries in use that in fact do "modify" the namespace
declarations (often for efficiency). Elements in scope that are typed
as QNames get fixed up (I think), but QNames contained within strings don't.
That is what I believe is the heart of the matter.
Thanks indeed for cross posting, a very
good idea.
++++++++
Steve Graham
(919)254-0615 (T/L 444)
STSM, On Demand Architecture
Member, IBM Academy of Technology
<Soli Deo Gloria/>
++++++++
Susan Malaika/Santa Teresa/IBM
10/18/2004 01:24 AM
|
To
| "Patil, Sanjay"
<sanjay.patil@sap.com>
|
cc
| Steve Graham/Raleigh/IBM@IBMUS,
wsn@lists.oasis-open.org
|
Subject
| RE: [wsn] AI from telecon
10/11Link |
|
I find the description slightly confusing. Do processors
sometimes modify the prefixes specified in namespace declarations and sometimes
modify the prefixes used in expressions?
In any case, for interest - I am cross posting the
entry I just placed on the WSRF mailing list describing the approach the
XQuery group are taking to try to isolate the scope of namespaces through
the use of prologs.
Susan Malaika
.................................................................................................................................................................................................................................................................................................
To:
wsrf@lists.oasis-open.org
cc:
Subject:
[wsrf] Issue
WSRF24: Should the XPath evaluations in WSRF specs be made in the context
of some namespaces defined or not
I'd like to draw your attention to the approach the
W3C XQuery group took in http://www.w3.org/TR/xquery/
Note that XQuery uses XPath.
XQuery defines a host environment- What's outside
the line in Figure 1 here http://www.w3.org/TR/xquery/#id-processing-model
In general, XQuery takes what the host environment
gives it, adds or overrides with prolog directives, and then evaluates
the XQuery expression.
Each prolog directive is different. For variables,
adding a new binding will occlude a binding from the environment. (occlude
: the inner scope hides the outer scope for these variables). See the tables
here
http://www.w3.org/TR/xquery/#id-xq-context-components
The WSRF TC may want to contact the XQuery co-chairs
before (or perhaps instead of) writing to the W3C as a whole. I've already
spoken to Andrew Eisenberg (one of the XQuery co-chairs) about issue WSRF24
- so the XQuery group won't be surprised to hear from the WSRF TC.
Susan Malaika
................................................................................................................................................................................................................................................................................................
To:
Steve Graham/Raleigh/IBM@IBMUS,
wsn@lists.oasis-open.org
cc:
Subject:
RE: [wsn] AI
from telecon 10/11
Following is my proposed text for this new issue. Please
review.
Thanks,
Sanjay
WSN2.31: Namespace prefix change may result into
unbound QNames
Some of the message components (such as TopicExpression
and Selector) may include QName strings in their value. The
namespace prefixes used in the QNames are normally declared by some
in-scope parent element.
It is possible that toolings modify the namespace
declarations and change the prefix values without necessarily updating
the QName strings appearing in the message content, resulting into
unbound QNames.
Specifications
Proposed Recommendations
Steve made the following proposal via email - http://www.oasis-open.org/archives/wsn/200410/msg00021.html
For each message exchange that describes a component
that may include a QName embedded in a string, the following normative
text be included in the description of that component:
If the value of the component contains QNames, then the
namespace declarations that specify the mapping of the QName's prefix
to an actual namespace URI can be found amongst any namespace declaration
in scope for the component. Note: Some XML processors MAY modify
the namespace declarations. Designers should be aware that such transforms
exist and may render the expression incoherent, as it is likely the
change in namespace declaration will not update a QName embedded
within a string.
Notes
http://www.oasis-open.org/archives/wsn/200409/msg00031.html
Status: Open
Date: Oct 11, 2004
Contact:
Igor Sedukhin
Cross Reference:
WSN2.12 raises a related issue.
-----Original Message-----
From: Steve Graham [mailto:sggraham@us.ibm.com]
Sent: Monday, Oct 11, 2004 10:37 AM
To: wsn@lists.oasis-open.org
Subject: [wsn] AI from telecon 10/11
I took an AI to suggest resolution text to the proposed
problem:
>Problem with the use of namespace prefixes in
topic and selector expressions. Client tooling may modify the the
>prefixes used
>in a web service request, so prefixes used in
these expressions may become unbound. Igor has observed a similar
>problem in WS-E[6]
I propose the resolution be as follows:
For each message exchange that describes a component
that may include a QName embedded in a string, the following normative
text be included in the description of that component:
If the value of the component contains QNames, then
the namespace declarations that specify the mapping of the QName's
prefix to an actual namespace URI can be found amongst any namespace
declaration in scope for the component. Note: Some XML processors
MAY modify the namespace declarations. Designers should be aware
that such transforms exist and may render the expression incoherent, as
it is likely the change in namespace declaration will not update
a QName embedded within a string.
sgg
++++++++
Steve Graham
(919)254-0615 (T/L 444)
STSM, On Demand Architecture
Member, IBM Academy of Technology
<Soli Deo Gloria/>
++++++++
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