Mash-ups are cool – ever since Ordnance Survey, Google, Yahoo! and Microsoft launched there various mapping APIs we’ve seen quite a few of them. This weekend I’ve been experimenting with creating a map mesh-up. I’m not sure if there is any strict definition of a mesh-up, but Kinglsey Idehen gave a pretty good account of mesh-up versus mash-up in this blog entry. I’ll leave it up to you the reader to decide if what I have done is truly a mesh-up, but I like to think I did the best I could given the current semantic web infrastructure.
Given my day job I thought it would be cool to do some kind of map mesh-up around regions in the UK (however being a typical researcher I’ve only done four locations so far just to prove the concept). The new version of Ordnance Survey’s mapping API (OS OpenSpace) provides easy API calls to let you display the boundaries of administrative regions in Great Britain (except for civil parishes and communities). This made OS OpenSpace a no brainer for this mesh-up (and of course the superior cartography is an added bonus :)). In order to process the RDF I used the ARC PHP library.
I’ll now explain how I did each of the various mesh-ups starting with the most straightforward one – the basic map with region information (e.g Southampton). This basic map mesh-up was made using the Ordnance Survey RDF for administrative units in Great Britain. This is hosted as linked data on the rkbexplorer site and has a SPARQL endpoint. This RDF data contains topological relations and name information for the administrative regions in Great Britain. For example, take a look at Southampton. For a given region the ARC library was used to issue a SPARQL query to find the bordering regions, contained regions and containing regions along with the area of the region. The result of these queries was then displayed in the map information pop-out. So to find the bordering regions for Southampton the query is very straightforward:
<http://os.rkbexplorer.com/id/osr7000000000037256> admingeo:borders ?border .
The family tree mesh-up was done in a similar way. I documented in a previous blog entry how I had started converting my family tree into RDF. In fact since my last blog entry I now have that data available as linked data (this was done using Paget, for example: http://www.johngoodwin.me.uk/family/I0002). The data was stored on the Talis Platform and again ARC was used to do a SPARQL query. You may notice for the Birmingham family tree map I list members of my family that were born in Birmingham and died in Birmingham. I also list relatives that were born in areas bordering Birmingham. I was able to do this because my family tree data was connected to the Ordnance Survey boundaries RDF. So from the OS data I could find all areas bordering Birmingham, and then return all family members born in these areas from my family tree data. Because the data was linked over the web is was easy to do this in a very simple SPARQL query:
SELECT ?s ?name
?place admingeo:borders <http://os.rkbexplorer.com/id/osr7000000000000018>.
?s dbpedia-owl:birthplace ?place .
?s foaf:name ?name
The BBC mesh-ups are arguably more interesting. The BBC recently announced a SPARQL endpoint for its RDF data. An example of the queries you can do are given here. The observant amongst you will notice that the BBC data does provide location information, but the URIs for the location are currently taken from DBpedia and not from the Ordnance Survey data. To get round this I used a new service called sameas.org. The sameas.org service offers a service that helps you to find co-references between different data sets. You can use this to look up other sources that represent your chosen URI. For example http://os.rkbexplorer.com/id/osr7000000000037256 has the equivalent URIs given here.
However, I didn’t want to hard code the equivalent URIs in my code. I’ll explain what I did using the Southampton example. First I issued a call to sameas.org to look up coreferences for the Ordnance Survey Southampton URI. I returned the URIs as an RDF file and used the ARC library to parse the RDF file for equivalent resources from dbpedia. I then issued a SPARQL query using the dbpedia URIs to return the artist/programme information from the BBC SPARQL endpoint. So in a nutshell:
- take Ordnance Survey URI
- issue a look-up for that URI to sameas.org
- return URIs in an RDF file
- parse the RDF file using ARC for dbpedia URIs
- issue query to BBC endpoint using the dbpedia URIs.
The revyu mesh-up was done in a similar way.
I hope this all made sense. Comments and questions welcome – though please no comments on my HTML/web design being very 1995. It’s all about the RDF for me :)
The mesh-up is here http://www.johngoodwin.me.uk/boundaries/meshup.html