[whatwg] RDFa

Ian Hickson ian at hixie.ch
Sat Aug 23 03:43:56 PDT 2008

On Sat, 23 Aug 2008, Julian Reschke wrote:
> Ian Hickson wrote:
> > On Sat, 23 Aug 2008, Julian Reschke wrote:
> > > Again you're confusing HTTP URLs with URIs.
> > > 
> > > Using URIs as identifiers allows lots of identification schemes 
> > > other than HTTP, in particular ones that are not based on DNS, or 
> > > that use DNS, but include a timestamp to address the concern of 
> > > "losing" a domain name (tag URI scheme).
> > 
> > Sure, but most people use HTTP URIs anyway for namespaces.
> > 
> > You can use any URI or any system you want with class="". The key is 
> > just to make it unique enough that clashes won't happen. In practice, 
> > names like "dc:title" are actually quite unique enough. But people can 
> > use much more unique ones if desired, all the way to full URIs.
> Yes, but unless they actually do use URIs, there's always the potential 
> of clashes. They may be unlikely, but they are possible -- that's one of 
> the reasons we have URIs, remember?

Worrying about clashes between "obviously unique" class names like 
"variable.example.org" or "dublincore:title" is like worrying about 
clashes between hash codes. Sure, they can happen, but unless someone is 
being malicious it is really not worth worrying about it.

Put it this way:

Using URIs is definitely a problem; people invent entire declaration 
syntaxes to route around them (c.f. XML namespaces).

Using unambiguous class names like Java does is maybe a problem due to 

Unless we can demonstrate that the clashes are more of a problem than the 
use of URIs, we would be foolish to put our eggs in the URI basket.

One good way to see whether it really is a problem is to look at the Java 
ecosystem. Have clashes been a big problem there?

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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