[tdwg-guid] Globally unique vs. globally locatable

Roderic Page r.page at bio.gla.ac.uk
Sat Jun 16 20:33:59 CEST 2007

On 13 Jun 2007, at 17:52, Ricardo Pereira wrote:

>    I would argue that, without loss of generality, any identifying  
> scheme considered by this group (LSID, DOI, Handles, ARK and any HTTP  
> URL based scheme) fulfill both use cases. Since we are interested in  
> sharing data, the 2nd use case is far more important for us than the  
> first. For that reason, I would suggest that any other scheme that  
> provide globally unique but non-locatable identifiers (i.e. that  
> fulfill use case #1 but not #2) would be irrelevant to this group.

Just to be contrary, I think case #1 will still be highly relevant,  
especially for the task of figuring out whether two GUIDs issued by  
different sources refer to the same thing. For example, many taxonomic  
database are likely to share the same publications, and if they issue  
their own identifiers for those then there will be multiple GUIDs for  
the same publication.

Some poor fool will have to reconcile these at some point. This is what  
I spend most of my time doing, and it is not fun. To give a concrete  
example, if the metadata for a journal article includes the ISSN of the  
journal and/or  a SICI for the article, then inferring that the two  
articles are the same is much easier. ISSNs and SICIs are both globally  
unique identifiers that are not, by themselves, resolvable.

In a sense this is an argument for separating identifiers from  
resolution mechanism, and for having a canonical representation of  
identifiers. For example, if I want to refer to a DOI in metadata for a  
publication, do I refer to this as:

http://dx.doi.org/10.1643/CH-04-083R1, or
doi:10.1643/CH-04-083R1, or
10.1643/CH-04-083R1, or
info:doi/10.1643/CH-04-083R1 ?

The INFO URI scheme addresses some of these issues. The first  
(http://dx.doi.org/10.1643/CH-04-083R1) seems problematic because if  
doi.org restructures their website this proxy may disappear (unlikely  
given the howls of protest that would ensure, but not impossible).

I guess my concern in all of this is that there are some items for  
which only a single GUID is likely to ever be issued (specimens in  a  
museum or institution database), and items where multiple GUIDs are  
likely (literature, names, concepts). It's the shared stuff that will  
make biodiversity informatics fly, so having mechanisms to avoid  
massive duplication of these would be desirable.



>    Such a scheme would still be important for cases other than sharing  
> data, but that discussion would be outside of the scope of this group.
>    If you are interested in discussing the best way to make your local  
> identifiers globally unique (which was the issue that started this  
> discussion I suppose), that's the subject of another (very relevant)  
> thread. For now the only thing I'll say about that is that there are  
> guidelines for making local identifiers globally unique in each  
> identifying scheme. In the particular case of LSIDs you may find  
> information about that in the following documents:
> * The LSID Specification - http://www.omg.org/cgi-bin/doc?dtc/04-05-01)
> * LSID Best Practices (Naming conventions) -  
> http://www-128.ibm.com/developerworks/opensource/library/os-lsidbp/
> * LSID Namespaces discussion -  
> http://wiki.tdwg.org/twiki/bin/view/GUID/LSIDResolverNamespaces
>    In any case, rest assured that we will sum up all those guidelines  
> into a section of the Bratislava Declaration ;)
>    Cheers,
> Ricardo
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Professor Roderic D. M. Page
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