Wednesday, December 21, 2005

Spiral mySQL Schema 

Semantic Planet :: Spiral mySQL Schema: "I've been reading Benjamin Novack's writing on exploding triple stores with interest and took some time to speak with him about it at ISWC this year. It prompted me ot take another look at the mySQL triplestore used by Spiral. This is a little write up of the design of that triplestore database.

First, let me explain a little about the RDF representation used in Spiral which might be a little different to other frameworks. Spiral is resource-centric rather than graph-centric. In concrete terms Spiral has a Resource class which has zero or more graph nodes associated with it. A graph node can only be associated with a single resource. Without smushing or reasoning each resource always has one node. The smushing process generally finds nodes that denote the same resource and so these associations can simply be updated.

The TripleStore interface provides various methods to deal with either resources or graph nodes and their associations. For example there's a GetResourceDenotedBy method which gives you the resource that a particular graph node denotes. Conversely there's a GetBestDenotingNode method which gives you a graph node for a particular resource. Generally this will give you a URI if the store knows of one, otherwise you'll get a blank node (I'm ignoring literals here). You can also get a list of all nodes for a resource using GetNodesDenoting. Finally you can build associations by using AddDenotation which takes a graph node and a resource pairing.

This is the model we wanted to follow when designing the mySQL support in Spiral. We already had a memory based triple store working well but we knew we wanted to support much larger persistent stores.

In Spiral a triplestore is equivilent to a named graph. Each mySQL database can store multiple triplestores. We use a Graphs table to partition the space. Each graph has a unique id. I'd like to see this changed to a URI to be more consistent with other implementations of named graphs."

Tuesday, December 20, 2005

Timothy Grayson's Articles on Identity 

Timothy Grayson's Articles on Identity: "The pieces available on this page are the running development of my thinking about a rapidly developing commercial and social subject area. Because I'm not a technologist, it may be that the ideas put forth are more robust and broadly relevant. Alternatively, they could be gibberish. That's your problem. What I can promise is a little logic, some history, a few laughs, and alternative perspectives (not realities -- one's quite enough for me, thank you very much)."

Sunday, December 18, 2005

Yahoo Web Services and JavaScript Object Notation 

O'Reilly Radar > eval( '(' YahooWebServices ')' );: "Our friend Jeff McManus over at the Yahoo! Developer Network clued us in to Y! Web Services now being available in a delicious new flavor: JSON--JavaScript Object Notation. Say bye-bye to XML parsing and the need for (very much) intermediary code when building Web 2.0 or single-page applications using Y!'s services and data. Simply fetch a wodge of JSON representing serialized results from Yahoo!'s servers, eval() (pronounced 'evaluate') to turn it back into a JavaScript object, and your application is dealing with ordinary JavaScript objects. And even if you're not writing your code in JavaScript, there's most likely a JSON parser for your programming language of choice, allowing you to skip all the XML bits and get on with your application."

URI crisis solved! 

Xam.de - Personal KM with Semantic Wikis: URI crisis solved!: "URI crisis solved! Finally, after some ciders and an enlightening talk from Sir Tim Berners-Lee himself at the ISWC2005, we solved the URI crisis *again*. Timbl insisted on '#' hash instead of '/' slash at the end of URIs. If we agree that web URLs denote the location of a document or anything that can be represented as a document and that the fragment identifiert (anything after the '#') is just some nice and funny thing browsers to within a particular kind of documents (in HTML pages they scroll down a bit), well then we can conclude: Everything with a '#' is a URI. Thus we can link to the page dog in Wikipedia via 'http://en.wikipedia.org/wiki/Dog' and to the concept described in that page via 'http://en.wikipedia.org/wiki/Dog#' or if thats illegal we use 'http://en.wikipedia.org/wiki/Dog#c' with a 'c' for concept. Of course, in RDF we still have to state the relationship between the two. Ah, and we can make it even cooler: 'http://en.wikipedia.org/rdf/Dog#' could refer to the concept and 'http://en.wikipedia.org/rdf/Dog' would be the location of the RDF document of the same data."

what do URIs identify? 

Semantic World and Cyberspace: uri crisis - what do URIs identify?: "Still, we don't use the Semantic Web in broad and I think one problem is, that we don't find the right uris to identify ideas/people/things - concepts from the real world. The discussion about the URI crisis does not happen in conferences and articles, but everytime somebody proposes a new uri scheme to identify books, lifescience terms, etc. Then masses of people flame each other on mailinglists.

There are nifty approaches about to cure the identity crisis (like this here) but they all fail the problem because the problem is much deeper.

I usually then write one email saying 'uri crisis again' to point out that the problem is unsolved.

So, what is the Uri crisis about?"

URI crisis and some good points of view 

Casual.info.in.a.bottle - Blog Archive - URI crisis and some good points of view: "My 2 cents

I'm thinking on it and from an RDF point of view i have already some troubles with URIs...

In fact when i want to make a statement about something that has an URL that's no problem... But what about something not in the Net, something like love or a person or a concept...

My understand of RDF world allows me to use my own domain - dagoneye.it - to make URI about all i want and that's it...
Than if i'll found another URI that indicates and identifies the same thing i can make a triple using owl:sameAs property for example...
Remembering the open nature of RDF model...

But if i don't have a domain?

And as we can see using an URI with the http protocol is correct or is it a better solution using the urn prefix?

A URI doesn't have any implicit meaning, but a social meaning derivated from the people use of that URI: the idea of using Wikipedia and Wordnet URLs for concepts identification is a social solution that IMHO it's a very good idea...

We can think that from the project and the efforts of a Semantic Wikipedia where every URL returns the content for the humans but also for the machines ( in RDF of course ) is a permanent evolution of the Web and offers us the URIs to identify things accepted from the community...

And using XRI maybe... [ i don't know enough this initiative to comment on it ]

Another example of the bottom-up design of Internet and the Web

So using this social implication of URIs, better tools and a clear way of producing RDF resources it's the next step: and the comprehension that RDF is still usable alone in small world applications like Shelley Powers efforts show us.."

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