[IPT] How to add his own/custom extension

Tim Robertson [GBIF] trobertson at gbif.org
Fri Mar 14 16:32:11 CET 2014

Hi Julien,

Thanks for your question.  It really depends on what you are trying to publish.  We can add extensions of course, but without knowing the specifics it is difficult to comment.

However, a “specimen, event, location” DB model would typically map to an Occurrence core with no extensions required - this is the most common use case of Darwin Core and the IPT.  An Occurrence core is basically a denormalized view of the data.

If I were the data manager, I would probably consider that I was publishing a “DwC Occurrence view” of my more complex model and as such would keep a view in the database along the lines of:

CREATE VIEW view_dwc_occurrence AS
  specimen.bar_code AS occurrenceID,
  specimen.name AS scientificName,
  location.latitude AS decimalLatitude,
  location.longitude AS decimalLongitude,
  event.year AS year
  JOIN event ON … 
  JOIN location ON …
  <insert any conditions for record inclusion, such as non endangered etc>

Then in my IPT I would simply do “SELECT * FROM view_dwc_occurrence”.  Here you are flattening the normalised model into a denormalized DwC view of the data.

Maintaining a view in the database layer as opposed to a custom mapping in the IPT benefits you by:
  i) catching issues early with database schema changes since the DB will likely stop you with an error
  ii) offering an easy mapping of DB table field names, to DwC terms in a language I find very familiar (SQL)
  iii) a super simple IPT mapping, as all columns will map automatically in the IPT since they are DwC recognised terms already

Does that help in any way?  If not, could you please elaborate on the model and what you are trying to achieve and we’ll do all we can.



On 14 Mar 2014, at 16:06, Julien Husson <biology.info at gmail.com> wrote:

> Hi,
> I use Dwc-A to feed my BD.
> We know the limits of the Dwc star schema to represent a relationnal database.
> For example in the case of 1-n cardinality :  specimen --- event/record --- location.
> If i understand the concept, I need to use the Darwin Core Occurrence extension, denormalize my relational model in a big raw model and transform / re-normalize this model to match with my DB model.
> In order to reduce cost, dev and optimize sql statement, it will be grandly appreciate to add custom extension. In this case, i can to be very close of my relational database model and avoid multiple step of dev.
> I discovered this link but explanantion is now deprecated
> http://dag-endresen.blogspot.fr/2009/06/adding-extension-for-germplasm-to-gbif.html
> Thanks,
> J.
> _______________________________________________
> IPT mailing list
> IPT at lists.gbif.org
> http://lists.gbif.org/mailman/listinfo/ipt

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