Dan Brickley wrote:
+cc: Norm Walsh
On 25/6/09 19:39, Juan Sequeda wrote:
So... then from what I understand.. why bother with content negotiation,
right?
Just do everything in RDFa, right?
We are planning to deploy soon the linked data version of Turn2Live.com.
And we are in the discussion of doing the content negotiation (a la
BBC). But if we can KISS, then all we should do is RDFa, right?
Does every major RDF toolkit have an integrated RDFa parser already?
And yep the conneg idiom isn't mandatory. You can use # URIs, at least
if the .rdf application/rdf+xml mime type is set. I believe that's in
the Apache defaults now. At least checking here, a fresh Ubuntu
installation has "application/rdf+xml rdf"
in /etc/mime.types (a file which I think comes via Apache but not 100%
sure).
But yes - this is a major problem and headache. Not just around the
conneg piece, but in general. I've seen similar results to those
reported here with "write yourself a FOAF file" exercises. Even if
people use Leigh Dodd's handy foaf-a-matic webforms to author a file
... at the end of the session they are left with a piece of RDF/XML in
their hands, and an instruction to "upload it to their sites". Even
people with blogs and facebook profiles and twitter accounts etc. can
find this daunting. And not many people know what FTP is (or was).
My suggestion here is that we look into something like OAuth for
delegating permission tokens for uploading files. OAuth is a protocol
that uses a Web/HTML for site A to request that some user of site B
allow it to perform certain constrained tasks on site B. Canonical
example being "site A (a printing company) wants to see non-public
photos on site B (a photo-sharing site)". I believe this model works
well for writing/publishing, as well as for mediating information access.
If site A is an RDF-generating site, and site B is a generic hosting
site, then the idea is that we write or find a generic OAuth-enabled
utility that B could use, such that the users of site B could give
sites like A permission to publish documents automatically. At a
protocol level, I would expect this to use AtomPub but it could also
be WebDAV or another mechanism.
But how to get all those sites to implement such a thing? Well
firstly, this isn't limited to FOAF. Or to any flavour of RDF. I think
there is a strong story for why this will happen eventually. Strong
because there are clear benefits for many of the actors:
* a data-portability and user control story: I don't want all my music
profile info to be on last.fm; I want last.fm to maintain
http://danbri.org/music for me.
* a benefits-the-data source story: I'm sure the marketing teams of
various startups would be very happy at the ability to directly push
content into 1000s of end-user sites. For the Google/Link karma,
traffic etc.
* benefits the hosts story: rather than having users share their FTP
passwords, they share task-specific tokens that can be managed and
rolled back on finer-grained basis
So a sample flow might be:
1. User Alice is logged into her blog, which is now AtomPub+OAuth
enabled.
2. She clicks on a link somewhere for "generate a FOAF file from your
music interests", which takes her to a site that asks some basic
information (name, homepage) and about some music-related sites she uses.
3. That site's FOAF generator site scans her public last.fm profile
(after asking her username), and then does the same for her Myspace
and YouTube profiles.
4. It then says "OK, generated music profile! May we publish this to
your site? It then scans her homesite, blog etc via some
auto-discovery protocol(s), to see which of them have a writable
AtomPub + OAuth endpoint. It finds her wordpress blog supports this.
5. Alice is bounced to an OAuth permissioning page on her blog, which
says something like:
"The Music Profile site at example.com would like to
have read and write permission for an area of your site:
once/always/never or for 6 months?"
6. Alice gives permission for 6 months. Some computer stuff happens in
the background, and the Music site is given a token it can use to post
data to Alice's site.
7. http://alice.example.com/blog/musicprofile then becomes a page (or
mini-blog or activity stream) maintained entirely, or partially, by
the remote site using RDFa markup sent as AtomPub blog entries, or
maybe as AtomPub attachments.
OK I'm glossing over some details here, such as configuration, choice
of URIs etc. I may be over-simplifying some OAuth aspects, and
forgetting detail of what's possible. But I think there is real
potential in this sort of model, and would like a sanity check on that!
Also the detail of whether different sites could/would write to the
same space or feed or not. And how we can use this as a
page-publishing model instead of a blog entry publishing model.
I've written about this before, see
http://markmail.org/message/gplslpe2k2zjuliq
Re prototyping ...
There is some wordpress+atompub code around, see
http://74.125.77.132/search?q=cache:KcriYA9UohcJ:singpolyma.net/2008/05/atompub-oauth-for-wordpress/+wordpress+oauth&cd=3&hl=en&ct=clnk&client=firefox-a
Also I just found
http://rollerweblogger.org/roller/entry/oauth_for_roller
And in http://danbri.org/words/2008/10/15/380 there is a point to some
Google announcements from last year.
I hope someone on these lists will find the OAuth/AtomPub combination
interesting enough to explore (and report back on). I've also Cc:'d
Norm Walsh here who knows AtomPub inside out now.
Is this making sense to anyone but me? :)
Dan,
It has always made sense to me. I call what you describe a Data Space
(others also use the term: Dataspace) :-)
A Data Space is limited to one activity of the artifacts resulting from
said activity. You should be able to put Blogs, Wikiwords, Photos,
Feeds, Calendars, Address-Books etc. in to a Data Space. You should also
be able generate conversation around any item of data that exists in a
Data Space (multi-dimensional objects of sociality etc..).
A Data Space would support a plethora of protocols (including OAuth,
FOAF+SSL, OpenID, AtomPub, and others).
OpenLink Data Spaces [1] has always been about all of the above and
some :-)
Links:
1. http://tr.im/pQuJ - An old ODS presentation (Slidy + RDFa based)
2. http://ods.openlinksw.com/dataspace/dav/wiki/ODS - Home Page
3. http://ods.openlinksw.com/dataspace/dav/wiki/ODS/VirtOAuthControllers
- OAuth support in ODS
Kingsley
cheers,
Dan
--
Regards,
Kingsley Idehen Weblog: http://www.openlinksw.com/blog/~kidehen
President & CEO
OpenLink Software Web: http://www.openlinksw.com
