Tom Morris gave a lightning talk on 'How to use Semantic Web data in your hack' (aka SPARQL and semantic web stuff).
He's since posted his links and queries - excellent links to endpoints you can test queries in.
Semantic web often thought of as long-promised magical elixir, he's here to say it can be used now by showing examples of queries that can be run against semantic web services. He'll demonstrate two different online datasets and one database that can be installed on your own machine.
First - dbpedia - scraped lots of wikipedia, put it into a database. dbpedia isn't like your averge database, you can't draw a UML diagram of wikipedia. It's done in RDF and Linked Data. Can be queried in a language that looks like SQL but isn't. SPARQL - is a w3c standard, they're currently working on SPARQL 2.
Go to dbpedia.org/sparql - submit query as post. [Really nice - I have a thing about APIs and platforms needing a really easy way to get you to 'hello world' and this does it pretty well.]
[Line by line comments on the syntax of the queries might be useful, though they're pretty readable as it is.]
'select thingy, wotsit where [the slightly more complicated stuff]'
Can get back results in xml, also HTML, 'spreadsheet', JSON. Ugly but readable. Typed.
[Trying a query challenge set by others could be fun way to get started learning it.]
One problem - fictional places are in Wikipedia e.g. Liberty City in Grand Theft Auto.
Libris - how library websites should be
[I never used to appreciate how much most library websites suck until I started back at uni and had to use one for more than one query every few years]
Has a query interface through SPARQL
Comment from the audience BBC - now have SPARQL endpoint [as of the day before? Go BBC guy!].
Playing with mulgara, open source java triple store. [mulgara looks like a kinda faceted search/browse thing] Has own query language called TQL which can do more intresting things than SPARQL. Why use it? Schemaless data storage. Is to SQL what dynamic typing is to static typing. [did he mean 'is to sparql'?]
Question from audence: how do you discover what you can query against?
Answer: dbpedia website should list the concepts they have in there. Also some documentation of categories you can look at. [Examples and documentation are so damn important for the update of your API/web service.]
Coming soon [?] SPARUL - update language, SPARQL2: new features
[These are more (very) rough notes from the weekend's Open Hack London event - please let me know of clarifications, questions, links or comments. My other notes from the event are tagged openhacklondon.
Quick plug: if you're a developer interested in using cultural heritage (museums, libraries, archives, galleries, archaeology, history, science, whatever) data - a bunch of cultural heritage geeks would like to know what's useful for you (more background here). You can comment on the #chAPI wiki, or tweet @miaridge (or @mia_out). Or if you work for a company that works with cultural heritage organisations, you can help us work better with you for better results for our users.]
There were other lightning talks on Pachube (pronounced 'patchbay', about trying to build the internet of things, making an API for gadgets because e.g. connecting hardware to the web is hard for small makers) and Homera (an open source 3d game engine).