W3C home > Mailing lists > Public > w3c-ietf-xmldsig@w3.org > July to September 2000

AW: Canonical XML Comment (CDATA)

From: Gregor Karlinger <gregor.karlinger@iaik.at>
Date: Wed, 13 Sep 2000 18:56:42 +0200
To: "John Boyer" <jboyer@PureEdge.com>, "XMLSigWG" <w3c-ietf-xmldsig@w3.org>
Message-ID: <NDBBIMACDKCOPBLEJCCDKENMCKAA.gregor.karlinger@iaik.at>
Hi John,

I agree with you, but maybe you could tweak the fourth paragraph of
section 2.1, so that it gets clear that the XML parser described there
is only a hypothetical model.

Regards, Gregor
---------------------------------------------------------------
Gregor Karlinger
mailto://gregor.karlinger@iaik.at
http://www.iaik.at
Phone +43 316 873 5541
Institute for Applied Information Processing and Communications
Austria
---------------------------------------------------------------



> -----Ursprüngliche Nachricht-----
> Von: John Boyer [mailto:jboyer@PureEdge.com]
> Gesendet: Mittwoch, 13. September 2000 18:33
> An: Gregor Karlinger; XMLSigWG
> Betreff: RE: Canonical XML Comment (CDATA)
>
>
> Hi Gregor,
>
> Thanks for writing.  Please respond to this letter even if you agree with
> its content since Joseph has asked that we document positive
> acknowledgement
> of the resolution of issues raised by the WG (esp. if we intend the
> resolution to be not to change anything).
>
> First, note that there is no requirement to use XPath to build
> the required
> part of C14N.  One's implementation must only behave in the same
> way, which
> includes replacing the CDATA sections with their character content.  The
> section about text nodes that you cited [XPath, Section 5.7]
> mentions CDATA
> sections in the discussion of text nodes, but it is in order to say
> *exactly* the same thing we are saying:
>
> "Character data is grouped into text nodes. As much character data as
> possible is grouped into each text node: a text node never has an
> immediately following or preceding sibling that is a text node."
>
> "Each character within a CDATA section is treated as character data."
>
> I believe it is best to make it clear up front that CDATA sections will be
> replaced rather than burying it in text node processing because
> it is easier
> for people who don't implement with XPath to see what must be
> done to make a
> logically equivalent structure appropriate to their purposes.
>
> My opinion is that the discussion of the processing model should
> be based on
> the data model, unencumbered by details of how to create the data
> model.  To
> me, this is esp. important given that some may choose to actually
> implement
> based on XPath (e.g. in order to perform document subsetting), and such
> people want to read the processing model to figure out how to process the
> data structure they have.
>
> As to your point about whether this concatenation is a common
> feature of XML
> processors, hopefully it is clear that it doesn't matter.
> Concatenation of
> successive blocks of character data is a trivial task.  Implementers can
> either choose to do it in their data structure, or they can
> acknowledge that
> since they are consecutive in the input, simply outputing the text as
> encountered suffices.
>
> It is important to note that while many processors may report separate
> character blocks for CDATA sections, they are not required (and
> some do not)
> distinguish that the text came from a CDATA section because:
>
> "CDATA sections may occur anywhere character data may occur; they are used
> to escape blocks of text containing characters which would otherwise be
> recognized as markup."
> [XML, Section 2.7]
>
> (In other words, CDATA sections are a simple escaping mechanism).
>
> [XML] http://www.w3.org/TR/1998/REC-xml-1998021
> [XPath] http://www.w3.org/TR/1999/REC-xpath-19991116
>
> John Boyer
> Development Team Leader,
> Distributed Processing and XML
> PureEdge Solutions Inc.
> Creating Binding E-Commerce
> v: 250-479-8334, ext. 143  f: 250-479-3772
> 1-888-517-2675   http://www.PureEdge.com <http://www.pureedge.com/>
>
>
>
> -----Original Message-----
> From: w3c-ietf-xmldsig-request@w3.org
> [mailto:w3c-ietf-xmldsig-request@w3.org]On Behalf Of Gregor Karlinger
> Sent: Wednesday, September 13, 2000 5:58 AM
> To: XMLSigWG; John Boyer
> Subject: Canonical XML Comment (CDATA)
>
>
> Hi John,
>
> In section 2.1 there are listed the requirements for an XML
> processor to be used to create a node set:
>
>  3. replace CDATA sections with their character content
>
> I am not sure, but I don't think this is standard behaviour of
> the widespread XML parser implementations.
>
> Wouldn't it be better to skip this requirement and instead
> add a sencence to the explanation how to serialize Text nodes
> in section 2.2?
>
> The XPath data model also mentions CDATA sections in the
> explanation of the data model [1].
>
> [1] http://www.w3.org/TR/xpath#section-Text-Nodes
>
> Regards, Gregor
> ---------------------------------------------------------------
> Gregor Karlinger
> mailto://gregor.karlinger@iaik.at
> http://www.iaik.at
> Phone +43 316 873 5541
> Institute for Applied Information Processing and Communications
> Austria
> ---------------------------------------------------------------
>
>
>
>
Received on Wednesday, 13 September 2000 12:55:45 GMT

This archive was generated by hypermail 2.2.0 + w3c-0.29 : Thursday, 13 January 2005 12:10:11 GMT