Some Strawman Amendments to the Identifier WD

• Part A.
• Part B.
• Part C.
• Part D

Part D. Persistant Dataset Identifiers (PDI) and ADEC Compatibility.

This proposal is intended to provide compatibility between the ADEC Dataset Verification and Resolution Services (DVRS) (http://ads.harvard.edu/www/dv/) and VO Registries. It recommends a choice for ADEC dataset identifiers that will allow a VO registry to locate the services for accessing that dataset. It makes use of LogicalIdentifiers proposed in Part B. and assumes that a dataset may or may not be explicitly registered.

• If the dataset is explicitly registered, then the URN form of the VO LogicalIdentifier should be given as the ADEC identifier.

• If the dataset is not registered, then the data collection should be registered. It is recommended that the provider implement a data resolver service as defined in the ADEC DVRS framework and include a reference to the service in the data collection's metadata.

If the data collection is not registered, then a service that serves that dataset (e.g. a data resolver service) should be registered.

The recommended ADEC identifier in this case should be LogicalIdentifier of the data collection or service, followed by a pound sign (#) and a unique dataset name.

• Given a VO-compliant ADEC identifier, one can resolve the identifier with the following recipe:
  1. The portion of the identifier prior to the # can be given to a searchable registry in by-LogicalIdentifier look-up query which would return one or more resources that can provide access to the dataset.
  2. If a matched resource is a DataCollection, its metadata is examined for a data resolver service.
  3. If a matched resource is a data resolver service or one was located from a matched DataCollection, the data resolver service can be called to get access to the dataset.
  4. If a data resolver service is not available, any of the matched DataCollections or Services can be returned to the user; however, further automated resolution may not be possible.

To make this proposal work, we recommend to ADEC the following:

• that VO Persistant Dataset Identifiers be accepted as ADEC identifiers.

Note that the current suggested, two-component form of ADEC identifiers may be used as an IVOA resource identifier, and thus, a PDI.

• that the DataResolver service be defined as a standard VO service.

• that the ADS use the standard DataResolver service to query data centers.