Hi, I have a couple of issues, I'm going to be terse, I don't have a lot of time today. 1) There are a couple of RDF initiatives to directed at fostering reuse and management of vocabularies; Dublin Core's DCMI and the Ontology Metadata Vocabulary (OMV). I'm not sure if they are mutually exclusive, complimentary or if they are interoperable. We need to determine the impact to our work. Maybe Roger Menday can help clarify ? 2) We need to take a close look at the html's RDFa's mapping. We should try to eliminate as much overlap as possible between elements and attributes that are already defined html and especially the items that affect browser renderings. See number 4 below 3) We need to decide whether the RDFa content is visible to browsers or we use JS to access RDFa elements and attributes. I had initially decided to make the RDFa invisible and use JS to reference information needed to be rendered. If we allow direct rendering, we will need to implement item list as number 4. 4) We also need to decide on the approach take to indicate relationships between occi objects. RDFa will allow a server to project one or more a occi graphs in a document or reference graphs across documents. Graphs may not be top down. We need a way to represent the references and type of relationship between graph elements. I was using the rel, rev, and href to indicate relationships between information elements and the backbone of decoupled graphs. Today, none of these attributes impact the rendering of content in browsers Although in certain areas we are back fitting RDFa mapping into the RDF vocabulary, I don't see a way to RDFa without remapping the RDF to RDFa vocabulary. cheers, gary Edmonds, AndrewX wrote:
You are more than welcome!
Just a little note: The Link entity is incorrectly modeled for those that have checked things out there's a bunch of attributes hanging off it. They should not. I'll update the python and owl files when committing to svn (2xTODOs)
Andy
-----Original Message----- From: Roger Menday [mailto:roger.menday@uk.fujitsu.com] Sent: Thursday, June 24, 2010 11:53 AM To: Edmonds, AndrewX Cc: occi-wg Subject: Re: [occi-wg] RDF, RDFa and HTML
hi Andy
thanks for posting this. I'm digesting (and I hope others are too). I am very interested in seeing where OCCI can go with this - I hope to get back to you soon.
Roger
On 23 Jun 2010, at 12:44, Edmonds, AndrewX wrote:
Hi all,
I've been looking into how OCCI can expose itself through a HTML serialization and to demarcate machine readable, semantic content. To demarcate that content we already decided that we would use RDFa [1]. In order to truly and correctly use RDFa we need to be able to point to the ontology (model) in which subject, predicate and object triplets are defined. Defining the ontology is somewhat easy, we have it already with the OCCI model; it's just a matter of expressing it in RDF. With an ontology in hand, we can define semantically marked-up HTML with the ontology's vocabulary using the facilities of RDFa. I've worked on 2 ways of expressing the OCCI model in RDF.
1. Using python [2]. 2. Using a modeling tool (Protégé) [3][4][5]. Note these owl files may need their imports modified in Protégé.
The only difference in the two is that occi.owl (core spec), occi- infrastructure.owl (infrastructure spec) and occi-sla-at-soi.owl (SLA@SOI extensions) are defined in separate files with the Protégé approach. This should give folks an idea of how extensions for OCCI can be introduced. However in both examples, occi-core, occi- infrastructure and slasoi-infrastructure are separated by namespace.
As RDFa does not explicitly define a rigorous structure for HTML documents, and it shouldn't, we need to be able to express 2 basics forms:
1. A concrete OCCI Kind instance (Compute, Storage, Network). I have an example here [6]. 2. A collection of OCCI Kind instances. I have an example here [7]. In this example values of objects are exposed using the 'content' RDFa attribute [8].
Each example may not be 100% perfect but what's most interesting is when you run the each HTML rendering through a RDFa parser [9] (examples here [10] [11]). The RDF extracted is quite along the lines of what some might expect an OCCI POX format to be. Note, I'm not advocating POX, just pointing to the flexibility of RDFa. There are still some aspects to be worked out but I will follow up on these in a separate mail (this one is long enough!).
If you want to see how all of this visually looks then see here: ontology only [12], ontology and graph instance [13].
I'd really appreciate and love to hear people's comments, opinions on this! :-)
Andy
[1] http://www.w3.org/TR/rdfa-in-html/ [2] http://dl.dropbox.com/u/165239/occi-rdf.py [3] http://dl.dropbox.com/u/165239/occi.owl [4] http://dl.dropbox.com/u/165239/occi-infrastructure.owl [5] http://dl.dropbox.com/u/165239/occi-sla-at-soi.owl [6] http://home.edmonds.be/occi-html5-rdfa-one.html [7] http://home.edmonds.be/occi-html5-rdfa-list.html [8] http://www.w3.org/TR/2010/WD-rdfa-core-20100422/#s_syntax [9] http://www.w3.org/2007/08/pyRdfa [10] http://www.w3.org/2007/08/pyRdfa/extract?uri=http%3A%2F%2Fhome.edmonds.be%2F... [11] http://www.w3.org/2007/08/pyRdfa/extract?uri=http%3A%2F%2Fhome.edmonds.be%2F... [12] http://dl.dropbox.com/u/165239/occi-rdf-graph-rev2.png [13] http://dl.dropbox.com/u/165239/occi-rdf-graph-inst-rev2.png
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