- From: McBride, Brian <bwm@hplb.hpl.hp.com>
- Date: Fri, 7 Apr 2000 10:55:51 +0100
- To: "'www-rdf-interest@w3.org'" <www-rdf-interest@w3.org>
Dan and Sergey, Thanks for the prompt responses. I think the heart of my difficulty is that I don't understand the role of anonymous resources. Let me replay my understanding of the answers to expose the bits I don't yet get: 1) What entitities can have digest URI's a) models b) statements c) otherwise anonymous resources Sergey wrote: >On the syntactic level, digests can be used to give explicit URIs to >"unnamed" resources used in some serialization syntax My reading of the spec is that anonymous resources appear in the model, not just in the syntax [m&s fig2, fig7]. Yes? No? This is the heart of my problem. 2) What are they for? Model URI's give us a digest to sign a model's content. [A digest algorithm would be sufficient for this - doesn't have to be a URI - Yes/NO? What advantage does making it a URI bring?] Statement digests improve interoperability? [I don't get this one yet. How? But they are needed to be able to compute the model digest - and a standard way to do that seems like a good thing.] Unnamed resources can be referred to. [I don't get that either. The algorithm for referring to unnamed resources depends on a particular seriliazation. If I've plonked an anonymous resource directly into a model in a database how do I compute its digest? Does this have knock on effect? The digests for statements referring to the unknown resource depends on the digest for that resource, and the digest for the model depends on the digests for those statements. So maybe the idea is: If a resource is added into a model by a program, then it is required to give it a URI - a guid or whatever. But since people are not very good at generating guid's, when a human writes some RDF serialization which includes an anonymous resource, then the parser has a standard algorithm for calculating a URI for that resource. If that is the case, then is this really a suggestion to remove anonymous resources from the RDF model?] 3) What does a digest URI denote What I was getting at here was the difference between variables and values. Digest URI's denote values, i.e. <Temperature, San Francisco, 10>, not "the current temperature in San Francisco" which is a variable. Obvious I guess, I was just trying to be careful. Brian McBride HPLabs
Received on Friday, 7 April 2000 05:55:56 UTC