Linking Open Data is a grassroots project to use web technologies to expose data on the web. It is for many people synonymous with the semantic web - and while this isn’t quite true. It does, as far as I’m concerned, represent a very large subset of the semantic web project.
Although, curiously, it can also be thought of as the ‘the web done right’ - the web as it was originally designed to be.
But what is it?
Well it can be described with 4 simple rules.
The web was designed to be a web of things, not just a web of documents.
Those documents make assertions about things in the real world but that doesn’t mean the identifiers can only be used to identify web documents.
Just as a passport or driving license, in the real world, can be thought of as identifiers for people so URI can be used as identifiers for people, concepts or things on the web.
Minting URIs for things rather than pages helps make the web more human literate because it means we are identifying those things that people care about.
The beauty of the web is its ubiquitous nature - the fact it is decentralised and able to function on any platform. This is because of TimBL’s key invention the HTTP URI.
URI’s are globally unique, open to all and decentralised.
Don’t go using DOI or any other identifier - on the web all you need is an HTTP URI.
And obviously you need to provide some information at that URI. When people dereference it you need to give them some data - ideally as RDF as well as HTML.
Providing the data as RDF means that machines can process that information for people to use. Making it more useful.
And of course you also need to provide links to other resources so people can continue their journey.
And that means contextual links to other resources elsewhere on the web, not just your site.
And that’s it. Pretty simple.
And I would argue that, other than the RDF bit, these principles should be followed for any website - they just make sense.
Before the Web people still networked their computers - but to access that network you needed to know about the network, the routing and the computers themselves.
For those in their late 30s you’ll probably remember the film War Games - because this was filmed before the Web they had to find and connect to each computer and know about the computer’s location. If you remember, they plugged their phone into a modem and phoned up the computer.
The joy of the web is because it adds a level of abstraction - freeing you from the networking, routing and server location and letting you focus on the document.
Following the principles of Linked Data allows us to add a further level of abstraction - freeing us from the document and letting us focus on the things, people and stuff that matters to people.
It helps us design a system that is more human literate, and more useful.
This is possible because we are identifying real world stuff and the relationships between them.
Of course there are other ways of achieving this - lots of sites now provide APIs which is good just not great.
Each of those APIs tend to be proprietary and specific to the site. As a result there’s an overhead every time someone wants to add that data source.
These APIs give you access to the silo - but the silo still remains.
Using RDF and LOD means there is a generic method to access data on the web.
So what are we doing at the BBC?
First up it’s worth pointing out the obvious, the BBC is a big place and so it would be wrong to assume that everything we’re doing online is following these principles. But there’s quite a lot of stuff going on.
So what do we have?
Well the BBC’s programme support, music discovery and, soon, natural history content are all adopting these principles.
In other words persistent HTTP URIs that can be dereferenced to HTML, RDF, JSON and mobile views for programmes, artists, species and habitats.
That means a page for every programme brand the BBC broadcasts on TV and Radio.
Separate, addressable episode pages
Soon we’ll have pages about individual concepts within the natural history domain - like species.
And we have separate pages for every artist the BBC plays on the new music site.
But resources are webpages - web pages are documents. We wanted HTTP URIs for every concept - and an individual page is made up of multiple resource, multiple concepts.
So for example the previous artist page transcludes this resource - but the resource also has it’s own URI.
If it doesn’t have a URI it’s not on the web.
And news stories by artist.
Remember there’s only one web so we only have one URI for a resource but a number of different representation for that resource.
So the URI for this programme is:
Through content negotiation we are able to server an HTML
...or mobile document to represent that programme.
We then need to link all of this stuff up within the BBC.
So that, for example, you can go from a tracklist on an episode page of Jo Whiley on the Radio 1 site to the U2 artist page and them from there to all episodes of Chris Evans which have played U2.
Or from an episode of Nature’s great events to the page about Brown Bears to all BBC TV programmes about Brown Bears.
But obviously the BBC is only one corner of the web. So we also need to link with the rest of the web.
So for example here are all the URI we know about that are about an artist. Note this set is also at a URI.
Because we’re thinking on a webscale we’ve started to think about the web as a CMS.
Where URIs already exist to represent that concept we using it rather than minting our own.
So the new music site transcludes and links back to Wikipedia to provide biographical information about an artist.
Rather than minting our own URI for artist biographic info we use wikipedia’s.
Likewise when we want to add music metadata to the music site we add MusicBrainz.
That’s my URI
Linking bbc.co.uk to the linked data cloud
Linking bbc.co.uk to the Linked Open Data cloud
Linked Data “The web done right”
Linked Data cloud diagram http://www4.wiwiss.fu-berlin.de/bizer/pub/lod-datasets_2009-03-05_colored.png
Use URIs to identify things
not only documents
How it works: The Web http://ﬂickr.com/photos/danbri/2415237566/
Use HTTP URIs - globally unique names that
anyone can dereference
Colon Slash Slash http://www.ﬂickr.com/photos/jeffsmallwood/299208539/
Provide useful information [in RDF] when someone
looks up a URI
Information Desk http://www.ﬂickr.com/photos/metropol2/149294506/
Include links to other URIs to let people discover
Good Question http://www.ﬂickr.com/photos/emagic/56206868/
Make computers human literate
Liverpool Street station crowd blur http://www.ﬂickr.com/photos/victoriapeckham/164175205/
Free information from data silos
Linked Data at the BBC
Test Card X http://www.ﬂickr.com/photos/marksmanuk/3098983708/
One page per programme, artist, species and