Feeler for SML (Simple Markup Language)

Tim Bray tbray at textuality.com
Mon Nov 15 18:45:39 GMT 1999


At 01:11 PM 11/15/99 -0500, Simon St.Laurent wrote:
>At 09:57 AM 11/15/99 -0800, Tim Bray wrote:
>>Hmm.... just specify the use of a nonvalidating processor.  These have the 
>>right to ignore external entities, not to barf, just to ignore them.  
>
>Nope, sorry, not that easy, unless you ...
>put big warning labels throughout indicating that external
>entities should not be used.  

Right, that's it exactly.  Even if you happen to be using a processor
that might try to resolve them.  Sorry, I just don't see this as a big deal.

>Otherwise, some brillant techie who built a
>system on Aelfred or MSXML will start using external entities for things
>like company identification headers and everyone else's systems will barf
>when they find &mycompany; in place of <company
>participant="z75006">....</company>.

Doing this kind of thing might make excellent sense if you define
your entities in the internal subset.  Save bandwidth, potentially.

But anyone who uses external parsed entities in an e-commerce application
is just stupid.  Yes, the XML 1.0 spec would be greatly improved if there
were some syntactic signal in the XML declaration saying "I promise not
to reference any external entities".  

But in fact there are all sorts of really stupid things you can do in
XML (remember the billion laughs?) and the spec won't stop you.  Using 
external entities inappropriately is just one of them.

I repeat my claim; for EDI-style messaging, XML 1.0, used appropriately,
doesn't get in the way.  It also doesn't lead us auto-magically to the
next generation of ssssssssssssssssssseamless new-paradigm next-gen
e-everything.  But it doesn't get in the way, and claims that we need
to split XML into multiple incompatible versions as part of a solution
to this non-problem are just silly. -Tim


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