Roger
I agree that PURLs are a perfectly good option for our GUID needs, and that they would probably be one of the easier technologies to get "working".
Like you I really had to think again to work out the benefits of LSIDs over PURLs, expecially considering the disadvantage you have mentioned.
Some of the benefits of LSIDs include: - clearly separate data and metadata services (as you have mentioned) - separation from domain names - as far as I understand, the PURL still requires domain name resolution of the actual ID url to obtain the resolution server address - this ties you to a particular url format - LSID assigning service can be managed by provider organisation ("ownership" of data and IDs is often high on a data provider's requirements list) - LSIDs provide a "standard" technology for resolving and serving up data objects - ie every provider will have the LSID authority services running on their server that will serve up data and metadata (+ other services if required) in the same way, for every provider - related to the previous point, a standard mechanism for third party annotations of LSIDs is provided with every LSID server implementation - same URN LSID can be used for resolution of http, ftp, soap and tcp protocols (unsure how PURLs handle this?) ...other cool stuff, I'm sure, that I cant think of right now - too late at night
Probably best to avoid LSIDs for RDF class identfiers etc, but do the semantic web tools you are talking about have no way of recognising different url resolution types - I'm wondering if you can "plug in" lsid resolution into these tools?
Kevin
Roger Hyam roger@tdwg.org 05/03/06 10:29 PM >>>
Hi Rod,
From the meeting report - which I am struggling to get back to - these two bullet points sum it up I think
· There are certain things for which LSIDs are not appropriate. It would be legal to use them for RDF resource identifiers for controlled vocabularies and XML Schema locations BUT we would have to extend existing software libraries to do this which is not desirable.
· *Recommendation:* LSIDs are not used for controlled vocabularies, ontologies or XML Schema locations. LSIDs should be used to refer to instances.
Basically it was felt that if we used LSIDs for things like rdfs:Class definitions then any library that went off to fetch the definitions automatically would have to be extended so that it understood LSID resolution. On the other hand it was felt that use of LSIDs for real resources (things we are actually describing like specimens and people) was fine. Once an ontology is loaded then it is all fine though so to an extent this may be a false problem.
We spent a long time talking about what is part of the ontology and what isn't and went round in circles (please lets not do it again). Basically class and property descriptions should be URL type URIs but instance URIs can be LSIDs. If you want to define the genus /Rhododendron/ as being an OWL DL class retrieved remotely then you should probably give it a URL. If you want to define it as a data item then use a LSID.
I think Gregor's worries (correct me if I am wrong Gregor) are that in SDD (possibly our whole domain) many things could be considered classes and properties. i.e. Things you want your reasoner to use in the reasoning rather than simply reason about. In this case it may be better to have URLs for everything.
There is a niggling doubt (in my mind) that we may come across 'cool' tools and libraries that assume that *all *resource URIs are URLs and that we would not be able to use them or would need to extend them if we use LSIDs. Imagine a semantic web browser where you click on a node and it fetches the associated resource to expand itself.
I do occasionally struggle to see the advantages of LSIDs as GUIDs over just conventions for use of URLs but these may be matters of personal faith. Another bullet point in the report says:
· *Recommendation: *GUIDs Group should issue a document clearly justifying adoption of GUID technology. The advantages need to be clearly explained.
I'll try and get this report out ASAP but it looks very similar to the wiki page here:
http://wiki.tdwg.org/twiki/bin/view/TAG/TagMeeting1ReportDraft
Obviously would be grateful for your thoughts.
Roger
Roderic Page wrote:
Dear Gregor,
For the benefit of those not at TAG 1, can you please explain why "LSIDs are not interoperable with semantic web technologies"?
Regards
Rod
On 2 May 2006, at 16:44, Gregor Hagedorn wrote:
Note that part of my concern about the use of concept when talking about classes/properties/data elements is that I more and more believe we will want to use ontology reasoners for uses other than software design, i.e. as part of what we currently consider data (taxon names, concepts, rank hierarchy, parts of organisms, properties of organisms, etc.). All these are ontological concepts, and efforts www.plantontology.org do use OWL to reason on them.
The SDD presentation (the one not held in EDI, attached) contained some examples how we might want to query our data - in ways that OWL-for-software- design seems not to cover - and which using LSIDs would even prevent.
Please discuss:
http://wiki.tdwg.org/twiki/bin/view/TAG/WhyWeShouldNotUseLSIDs
http://wiki.tdwg.org/twiki/bin/view/TAG/UsePURLsAsGUIDs
Gregor
Gregor Hagedorn (G.Hagedorn@bba.de) Institute for Plant Virology, Microbiology, and Biosafety Federal Research Center for Agriculture and Forestry (BBA) Königin-Luise-Str. 19 Tel: +49-30-8304-2220 14195 Berlin, Germany Fax: +49-30-8304-2203
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