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Service MD - Coupled resources #3

Open ByronCinNZ opened 4 years ago

ByronCinNZ commented 4 years ago

A basic issue in service metadata is the nature of the relation the service and the data on which it acts. It makes a big difference to how we capture service metadata whether these data are loosely or tightly coupled. An number of sub-issues here -

  1. By ISO 19115-1, if the data is tightly coupled, like a data delivery service of some type, then the “couplingType” is a required element and the “coupledService” must(?) be provided. We do not currently recommend it this way and give preference to using the ‘operatedDataset’ option. I now feel this to be arguably out of alignment with ISO guidance. But the guidance is not as clear as it could be on this issue. Many orgs use different approaches.

  2. So - We need to standardise how one should capture information about tightly coupled resources. ISO 19115-1 provides too many ways to do so. The couplingType and couplerService seems to me to be the most straight forward. But there are other options such as operatedDataset and operatesOn. OperatedDataset should be avoided so as to keep to one identificationInfo package to one metadata record.

  3. How do we reference the related coupled resource. Depending on the approach taken above, the metadata requirements differ - is it a citation or a identificationInfo package? Because of the desirability of having one resource described per metadata record, having multiple indentificationInfo packages in a single metadata record does not seem to me to be a good idea. The best approach in my opinion would be to reference these coupled resources by the uri or url of their metadata record. This normalises the data and keeps to the one resource per metadata record rule. However, there seems to be no well described way to do this. Perhaps under coupledResource?

asedgmen commented 4 years ago

In GA's service metadata, the operatesOn element is used to reference the related coupled resources. A link to an ISO 19115-3 dataset metadata record is provided in the xlink:href attribute of the operatesOn element, rather than embedding dataset metadata in the operatesOn element. It has become apparent that this approach is invalid. Resolving the xlink content into the service record would introduce the entire ISO 19115-3 dataset metadata record at the root MD_Metadata element level. To be valid, only the MD_DataIdentification component of the record should exist under operatesOn element.