W3C home > Mailing lists > Public > public-html@w3.org > July 2008

Re: [author-guide] Character Entity References Chart

From: Henri Sivonen <hsivonen@iki.fi>
Date: Tue, 22 Jul 2008 11:53:10 +0300
Cc: Karl Dubost <karl@w3.org>, Lachlan Hunt <lachlan.hunt@lachy.id.au>, public-html WG <public-html@w3.org>
Message-Id: <933592C5-7426-4EA5-A51E-EA9D493A6467@iki.fi>
To: Jirka Kosek <jirka@kosek.cz>

On Jul 22, 2008, at 11:39, Jirka Kosek wrote:

> Henri Sivonen wrote:
>> On Jul 22, 2008, at 03:45, Karl Dubost wrote:
>>>> Without an official DTD, no other references can be reliably used  
>>>> in XHTML 5.  Even if you provide your own custom DTD and DOCTYPE,  
>>>> most browsers don't use validating parsers and so won't be able  
>>>> to dereference the entity references.
>>> That is a false assumption. Browsers *can*, if they implement it,  
>>> deference the *named* entity references.
>> Implementing it is not feasible.
>> * It would cause a massive DDoS attack on www.w3.org.
>> * It would make www.w3.org a single point of failure for the Web.
>> * It would be bad for XML parsing performance.
>> * It would break compatibility with existing content (IIRC MIT  
>> courseware, for example) that refers to a DTD that is not namespace- 
>> well-formed (i.e. has colons in PI targets).
>> * New documents authored with the assumption that DTDs get fetched  
>> would break very ungracefully in existing Gecko and WebKit instances.
> Not that I'm fan of DTDs, but you can solve those problems by using  
> XML catalogs:
> http://www.oasis-open.org/committees/download.php/14809/xml-catalogs.html
> Each browser then will have local copies of well known DTDs and will  
> fetch only custom created ones.

How do catalogs address:
  * older browsers performing a DDoS on www.w3.org when a new DTD that  
isn't in the catalog is published
  * www.w3.org as a single point of failure when a DTD isn't in the  
  * parsing performance other than network
  * colons in PI targets
  * ungraceful behavior in existing Gecko and WebKit instances
  * the fact that the very reason why the XML spec doesn't require XML  
processors to process the DTD is to cater for browsers (see http://www.xml.com/axml/testaxml.htm) 
, so failing to exercise the opportunity not to process DTDs would be  
defeat the intent of the XML spec

Henri Sivonen
Received on Tuesday, 22 July 2008 08:53:55 UTC

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