[whatwg] Link rot is not dangerous

Henri Sivonen hsivonen at iki.fi
Mon May 18 05:26:25 PDT 2009

On May 18, 2009, at 14:45, Dan Brickley wrote:

> On 18/5/09 10:34, Henri Sivonen wrote:
>> It seems to me that the positions that RDF applications should  
>> "Follow
>> Their Nose" and that link rot is not dangerous (to RDF) are
>> contradictory positions.
> That's a strong claim. There is certainly a balance to be found  
> between taking advantage of de-referencable URIs and relying on  
> their de-referencability. De-referencing is a privilege not a right,  
> after all.

If there's value in apps dereferencing namespace URIs, those URIs  
going undereferencable leads to loss of value. Hence, link rot would  
cause loss of value i.e. be 'dangerous' by breaking something.

> If I lost control of xmlns.com tommorrow, and it became un-rescuably  
> owned by offshore spam-virus-malware pirates, that doesn't change  
> history. For nine years, the FOAF documentation has lived there, and  
> we can use URIs to ask other services about what they saw during  
> that period: http://web.archive.org/web/*/http://xmlns.com/foaf/0.1/

Do any RDF consumer apps that dereference namespace URIs actually fall  
back on web.archive.org?

If I'm a FOAF author, what recourse do I have if URI dereferencing- 
based functionality breaks in some apps due to xmlns.com going  
unavailable when other apps have hard-coded xmlns.com URIs so if I  
simply changed my predicates I'd break existing apps? At least authors  
who rely on Y!/AOL/Google serving JS libraries can start using a copy  
of any JS library on another CDN without changing how the script runs.

> Since there is useful information to know about FOAF properties and  
> terms from its schema and human-oriented docs, it would be a shame  
> if people ignored that. Since domain names can be lost, it would  
> also be a shame if directly de-referencing URIs to the schema was  
> the only way people could find that info. Fortunately, neither is  
> the case.

I wasn't talking about people but about apps dereferencing NS URIs to  
enable their functionality.

>> That link rot hasn't been a practical problem to the Semantic Web
>> community suggests that applications don't really Follow Their Nose  
>> in
>> practice. Can anyone point me to a deployed end user application that
>> uses RDF internally and Follows Its Nose?
> The search site, sindice.com does this:


> Whether you consider sindice.com end-user facing or not, I don't know.

I wouldn't characterize it as an end-user app. It exposes terms like  
"RDF" and "triples" and shows qnames to the user.

Henri Sivonen
hsivonen at iki.fi

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