This section has now been locked for editing and a draft version have been moved into the draft document.
See page: https://ies-svn.jrc.ec.europa.eu/projects/metadata/wiki/DraftVersionsMIWP-8
Further discussions and comments should be done on the draft
TG Requirement 6 suggests to use RS_identifier for the encoding of the resource identifier. This is a poor choice as it is (a) against the foreseen semantic in the ISO standard, which defines it as an “identifier used for reference systems” and (b) because it is not a CSW-queryable. As foreseen by the ISO-Standard the MD_Identifier (a “value uniquely identifying an object within a namespace”) should be suggested, which is also CSW-queryable. The task will be to recommend an “MD_Identifier” (a “value uniquely identifying an object within a namespace”).
Martin Seiler (Leader)
Part B, 1.5 Unique resource identifier¶
A value uniquely identifying the resource.
The value domain of this metadata element is a mandatory character string code, generally assigned by the data
owner, and a character string namespace uniquely identifying the context of the identifier code (for example, the
OpenGIS® Catalogue Services Specification 2.0.2 - ISO Metadata Application Profile¶
Table 10: The CSW-queryable 'ResourceIdentifier' ('Identifier of the resource') is mapped to 'MD_Metadata.identificationInfo. AbstractMD_Identification.citation.CI_Citation.identifier.MD_Identifier.code'
Technical Guidelines based on EN ISO 19115 and EN ISO 19119¶
(see attached files for now)
Issues / Tasks:¶
- Check semantics of identifiers in ISO 1915
- Definition in section 2.2.5 is not inline with IR
- TG: "Value uniquely identifying an object within a namespace"
- IR: "A value uniquely identifying the resource"
- TG section 2.2.5 is inconsistent with suggestion of metadata element to use
- In the table "205. MD_Identifier" is suggested
- in TG Requirement 6 RS_Identifier is suggested.
- Need to ensure consistency with TG section 2.2.6 Coupled Resource and examples in the annex
What problems causes current solution ?¶
What can be a solution on current problem (proposed)?¶
- Namespace and code of the Unique Resource Identifiers shall be encoded (at least) in: MD_Metadata/identificationInfo/MD_DataIdentification/citation/CI_Citation/identifier/MD_Identifier.code (e.g. https://namespace/code)
- Unique Resource Identifiers should not change/be deleted. If necessary additional identifiers should be added
- Requirements (Input for MIWP 4a : Set sub-group on Persistent Identifiers (PID))
- Unique Resource Identifiers shall be in the http(s)-scheme
- Unique Resource Identifiers should be dereferenceable
Use Cases for Unique Resource Identifier?¶
- Uniquely identify a resource in the SDI
- Realize data-service coupling
- the operatesOn element in a metadata set describing a service points to the Unique Resource Identifier of the resource provided in the metadata set describing the resource
How does it relate to IR ?¶
How will the solution affect existing tools ?¶
What other issues in MIWG-8 is related to this change ?¶
What other groups within MIG-related workgroups could be linked to this issue ?¶
Findings / Ideas / Solutions:¶
- #1: As per ISO, an MD_Identifier is “value uniquely identifying an object within a namespace”, whereas its direct subclass RS_Identifier is an “identifier used for reference systems”. From an encoding perspective one can use an instance of RS_Identifier in lieu of an MD_Identifier instance, but this is not intended by ISO; hence, an RS_Identifier shall be used as an identifier for reference systems only (e.g. as defined by MD_CRS or MD_ReferenceSystem). Thus, regarding the TG it is clear, that only an instance of MD_Identifier is applicable to identify the resource.
- #2: The TG is an implementation of requirements defined by the IR. This includes a representation of INSPIRE concepts in the ISO world, and that's what is happens here: the IR demands for a means to define "A value uniquely identifying the resource". This requirement is adressed by using the ISO elemtent MD_Identifier as its realization. Hence the ISO definition of MD_Identifier is a "value uniquely identifying an object within a namespace". So this is not an inconsistancy, but a mapping between the INSPIRE semantics (defined by the IR) and the semantics as defined by ISO.
- #3: put both the codespace and the code in one string in MD_Identifier, interpret the last part of the string after a seperator as 'code', e.g. 'urn:eu:europa:ec:jrc:rdsi:id:dataset:ccm2.1:lakes'
- codeSpace: 'urn:eu:europa:ec:jrc:rdsi:id:dataset:ccm2.1'
- code: 'lakes'
- # ...
- # ...