- From: Mark Birbeck <mark.birbeck@webbackplane.com>
- Date: Wed, 22 Apr 2009 22:57:47 +0100
- To: Toby A Inkster <tai@g5n.co.uk>
- Cc: RDFa <public-rdf-in-xhtml-tf@w3.org>, "public-rdfa@w3.org" <public-rdfa@w3.org>
Hi Toby, > Have you seen this? > > http://buzzword.org.uk/2008/jsonGRDDL/spec No I haven't...but it's very interesting. I take it that the goal is to work with JSON as one would do normally in our applications, and then if you want to serialise out those objects, to use jsonGRDDL to translate to RDF/JSON? If so -- and please correct me if I'm wrong -- my use cases are slightly different. My first use-case was actually to get RDFa into my applications from locations that caused cross-domain problems (parsing HTML documents from another domain with my parser doesn't work in all browsers). Much of the RDFa that I'm using contains JS functions, so when I wanted a JSON equivalent for my data, I wanted functions and other objects to be 'first-class' citizens. However, it's my second use-case that in my view is more interesting, and I think should explain why I didn't go for other JSON formats for my RDF, and that is that I want to be able to use RDF objects directly in my JS applications. Obviously there's no such thing as an 'RDF object', but what I mean by that is that by working out how JSON objects map to RDF, I can apply 'RDF features' to those objects. There are many ways I could illustrate this, but one I've just finished working on is a backward-chaining algorithm that operates over JSON objects; each property of the object is treated as a simple fact. I've only got simple rules working at the moment, such as checking for a specific value of a property, or checking that a property exists. But even with these two basic features I can do things like fill in missing properties in an object (i.e., infer them). For example, after setting the appropriate rules, I can start with this object: var vehicle = { engine: true, wheels: 4 }; and find out what what type of vehicle we have, by calling the backward-chaining function, like this: kb.bc("vehicleType", vehicle); Although my plan is to use forward-chaining on the object to actually keep the object up-to-date and add inferred properties -- hence the notion of 'semantic objects' that I've mentioned -- my focus for now is on adding more rule types for the backward-chaining. The reason is that I started this whole thing because I want to be able to 'validate' objects. Using backward-chaining my validation step will simply become: var foafPerson = { ... }; kb.prove( { name: "valid", value: true }, foafPerson ); and provided the correct rules appear in the knowledge base, I should be able to establish whether the JSON object is 'valid' or not. Of course, you've probably worked out that what I _really_ want to validate is RDFa documents, and the rules I'll be processing will be OWL constructs. :) This is because, amongst the various RDFa projects I'm involved with, a common problem I'm seeing is that people have no easy way to know if they have their RDFa laid out correctly at the RDF level. So, since I already have a parser that converts RDFa to triples, and I already have a rudimentary SPARQL-like way to query across those triples and create JSON objects with the results, then I figured that I might as well do backward-chaining against the JSON objects, and then put the whole sequence together to give me document validation. A long answer to a short question, I realise... All the best. Regards, Mark -- Mark Birbeck, webBackplane mark.birbeck@webBackplane.com http://webBackplane.com/mark-birbeck webBackplane is a trading name of Backplane Ltd. (company number 05972288, registered office: 2nd Floor, 69/85 Tabernacle Street, London, EC2A 4RR)
Received on Wednesday, 22 April 2009 21:58:32 UTC