[foaf-dev] is foaf graph limited to obtaining its bearer document from the uri of the named object in the graph?

Toby Inkster tai at g5n.co.uk
Tue Oct 27 11:38:22 CET 2009


On Tue, 2009-10-27 at 03:18 -0700, Peter Williams wrote:
> Or, is using a locator service just as valid a way of telling folks
> HOW to deference a webid - as is simply getting the document implied
> by the webid  name using HTTP GET directly?

If I give something (a person, a document, an abstract concept,
whatever) the URI <http://example.net/foo> then the RDF model allows for
data about <http://example.net/foo> to be made available anywhere. You
could provide data about <http://example.net/foo> at
<http://yourservice.example.org/describe?http://example.net/foo> and I
might provide some different data about <http://example.net/foo> at
some different address.

However, the data at <http://example.net/foo> itself is most easily
findable, so when possible, it is certainly preferable to put it there.

There is a social expectation -- especially within the Linked Data
movement -- that publishers of data, when minting URIs for things, will
arrange things so that the URIs are dereferencable and relevant data can
be retrieved from them.

> Now, if I were to go around telling folks that the foaf file of some
> friend is NOT to be obtained by simply following a webid name, but is
> to be located by doing an HTTP GET on the URI
> http://domainname/getfoaffiles?uri=<webid>, would that locator scheme
> be “contrary to semweb” doctrine? Is it contrary to foaf doctrine or
> linked data doctrine?

This would violate the principles of linked data, but there's no law
that says you're not allowed to violate the principles of linked data.
It's more important to understand the principles and why they are useful
than it is to blindly follow them.

The principle that URIs should be dereferencable is a useful one because
it allows user agents to find data easily without having to know about
site-specific conventions for retrieving data.

But sometimes there are other considerations that need to be taken into
account. If you need to publish some data about me, then short of
cracking into my server, there's no way for you to do it in a way that's
dereferencable from my WebID (<http://tobyinkster.co.uk/#i>) so you're
going to have to publish it somewhere else. And if I'm feeling kind, I
might provide an rdfs:seeAlso link to your data to help user agents find
it.

-- 
Toby A Inkster
<mailto:mail at tobyinkster.co.uk>
<http://tobyinkster.co.uk>



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