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NEED FEEDBACK TODAY RE: Comments for Transform

From: John Boyer <jboyer@uwi.com>
Date: Thu, 9 Dec 1999 10:45:17 -0800
To: "TAMURA Kent" <kent@trl.ibm.co.jp>, <w3c-ietf-xmldsig@w3.org>
Cc: "Joseph M. Reagle Jr." <reagle@w3.org>, "Donald E. Eastlake 3rd" <dee3@torque.pothole.com>, "Dave Solo" <dsolo@alum.mit.edu>, "Ed Simon" <ed.simon@entrust.com>
Message-ID: <NDBBLAOMJKOFPMBCHJOIMEKDCCAA.jboyer@uwi.com>
Document order is, in fact, defined in XPath.  The XPath spec says that
attribute and namespace nodes are in application dependent order, and within
the DSig application of XPath, the XPath Transform section defined that
order to be document order.

In the telecon this morning, I only had a minute to read the emails before
the call, and so I didn't remember at the time why I had selected document
order for attributes and namespaces.  I now recall that we had some feedback
that low-resource environments could, perhaps, respond more efficiently with
document order since it would be possible to react to the XML document as a
stream of bytes rather than having to put it through an XML processor on a
low-resource device.  The programming on the device could be quite specific
to the application, and hence probably quite small.

The main thing I need feedback on is whether document order is too
inconvenient for the majority of uses.  I know that a number of APIs tend to
put attributes in alphabetic order, and I do not know whether the document
order is recoverable (I don't think it is).

I need to know this before we decide to change the XPath transform section
to impose a different order.  The only other reasonable order seems to be
the order defined in the c14n spec [1].  Naturally, if the input to XPath is
canonicalized, then this is the same as document order, but for
uncanonicalized documents, this order would have to be imposed by the
(recommended) core behavior as part of interpreting the XPath.

[1] http://www.w3.org/TR/xml-c14n#sec-namespaces

Unfortunately, this decision implies non-local changes since namespace
propogate down to descendants that actually use them.  The non-local changes
are what lead me to select document order.

John Boyer
Software Development Manager
UWI.Com -- The Internet Forms Company


-----Original Message-----
From: w3c-ietf-xmldsig-request@w3.org
[mailto:w3c-ietf-xmldsig-request@w3.org]On Behalf Of TAMURA Kent
Sent: Thursday, December 09, 1999 12:39 AM
To: John Boyer; w3c-ietf-xmldsig@w3.org
Cc: Dave Solo
Subject: Re: Comments for Transform



In message "RE: Comments for Transform"
    on 99/12/07, "John Boyer" <jboyer@uwi.com> writes:
> Step #3 states that the node-set will be interpreted in document order,
> which is clearly defined in the XPath specification [1].
>
> [1] http://www.w3.org/TR/xpath#dt-document-order

No.  Order in a set of attribute nodes or namespace nodes is
implementation-dependent.

In http://www.w3.org/TR/xpath#dt-document-order
	....  The relative order of namespace nodes is
	implementation-dependent. The relative order of
	attribute nodes is implementation-dependent. Reverse
	document order is the reverse of document order.

--
TAMURA Kent @ Tokyo Research Laboratory, IBM
Received on Thursday, 9 December 1999 13:47:26 GMT

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