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- Update current default 'dc' schema in DSpace metadata registry to current qualified Dublin Core (QDC)
- Background:
- The default DSpace metadata registry ships with one schema - the 'dc' schema (which is the default DSpace metadata schema). It was designed to comply with the Dublin Core Libraries Working Group Application Profile, modeled on the flat, extensible Qualified Dublin Core standard. Soon after, the Dublin Core Metadata Initiative (DCMI) updated its Qualified Dublin Core (QDC) standard.
- [The default DSpace metadata registry schema is "namespace" = http://dublincore.org/documents/dcmi-terms/ and "name" = dc. This use of "dcmi-terms" should not be confused with DCMI Metadata Terms. It is a qualified 'dc' schema for DSpace based on an application profile (Dublin Core Libraries Working Group Application Profile (LAP)). DSpace used the LAP as the starting point for its application of Dublin Core, borrowing most of the qualifiers from it and adapting others to fit. Some qualifiers were also added to suit DSpace needs.The 'namespace' it is declaring is not a DCMI namespace. The default DSpace schema is not dc: namespace http://purl.org/dc/elements/1.1/ (the collection of legacy properties that make up the Dublin Core Metadata Element Set, Version 1.1 [DCMES]) or dcterms: namespace http://purl.org/dc/terms/ (the collection of all DCMI properties, classes and encoding schemes (other than the properties in the Dublin Core Metadata Element Set, Version 1.1 [DCMES], the classes in the DCMI Type Vocabulary [DCMI-TYPE] and the terms used in the DCMI Abstract Model) http://purl.org/dc/terms/)]
- [The default DSpace metadata registry schema is "namespace" = http://dublincore.org/documents/dcmi-terms/ and "name" = dc. This use of "dcmi-terms" should not be confused with DCMI Metadata Terms. It is a qualified 'dc' schema for DSpace based on an application profile (Dublin Core Libraries Working Group Application Profile (LAP)). DSpace used the LAP as the starting point for its application of Dublin Core, borrowing most of the qualifiers from it and adapting others to fit. Some qualifiers were also added to suit DSpace needs.The 'namespace' it is declaring is not a DCMI namespace. The default DSpace schema is not dc: namespace http://purl.org/dc/elements/1.1/ (the collection of legacy properties that make up the Dublin Core Metadata Element Set, Version 1.1 [DCMES]) or dcterms: namespace http://purl.org/dc/terms/ (the collection of all DCMI properties, classes and encoding schemes (other than the properties in the Dublin Core Metadata Element Set, Version 1.1 [DCMES], the classes in the DCMI Type Vocabulary [DCMI-TYPE] and the terms used in the DCMI Abstract Model) http://purl.org/dc/terms/)]
- The default DSpace metadata registry ships with one schema - the 'dc' schema (which is the default DSpace metadata schema). It was designed to comply with the Dublin Core Libraries Working Group Application Profile, modeled on the flat, extensible Qualified Dublin Core standard. Soon after, the Dublin Core Metadata Initiative (DCMI) updated its Qualified Dublin Core (QDC) standard.
- Desirability of and demand for QDC and DCTERMS compliance:
- Updating QDC to the latest standard of DCMI and Standardizing the default namespaces were identified as priorities in the October 2011 community survey on improving metadata support authored by DCAT at the request of the DSpace Committers/Developers. These updates were seen as standardizations that "would help compatibility with other systems and benefit from information gathered by the DCMI community" and would address the problem of broken compliance with the standard Dublin Core, which had affected portability to/from a repository.
- Updating QDC to the latest standard of DCMI and Standardizing the default namespaces were identified as priorities in the October 2011 community survey on improving metadata support authored by DCAT at the request of the DSpace Committers/Developers. These updates were seen as standardizations that "would help compatibility with other systems and benefit from information gathered by the DCMI community" and would address the problem of broken compliance with the standard Dublin Core, which had affected portability to/from a repository.
- Examples:
- Updates range from the very basic (change dc.identifier.citation to dc.identifier.bibliographicCitation; dc.description.provenance to dc.provenance; dc.date.copyright to dc.date.copyrighted) to the addition of QDC elements like dc.accrualMethod and dc.audience. If we are continuing to allow qualifiers to be added to QDC elements in the 'dc' schema, we may also continue to support the current qualified elements that are not specifically compliant with QDC (e.g., dc.contributor.editor). A preliminary mapping can be found here: https://wikidocs.duraspacegoogle.orgcom/download/attachments/32478705/DCAT+QDC+preliminary+%28posted+to+DCAT+8.15.2012%29.xlsxspreadsheet/ccc?key=0AgU-htsSmo31dEtaM1M1Q2E1NlRxNG11ZHFrSkMxNFE#gid=0
- Updates range from the very basic (change dc.identifier.citation to dc.identifier.bibliographicCitation; dc.description.provenance to dc.provenance; dc.date.copyright to dc.date.copyrighted) to the addition of QDC elements like dc.accrualMethod and dc.audience. If we are continuing to allow qualifiers to be added to QDC elements in the 'dc' schema, we may also continue to support the current qualified elements that are not specifically compliant with QDC (e.g., dc.contributor.editor). A preliminary mapping can be found here: https://wikidocs.duraspacegoogle.orgcom/download/attachments/32478705/DCAT+QDC+preliminary+%28posted+to+DCAT+8.15.2012%29.xlsxspreadsheet/ccc?key=0AgU-htsSmo31dEtaM1M1Q2E1NlRxNG11ZHFrSkMxNFE#gid=0
- Background:
- Add DCTERMS as new, parallel schema in the default metadata registry
- Background:
- DCMI has not updated its Qualified Dublin Core standard since 2005. The community standard has shifted towards DCMI Metadata Terms, which, unlike QDC, is not a flat schema based on the schema.element.qualifier format. DCTERMS include range and domain values. A particular term may link to another term that it refines or is refined by (for example: the dcterm "hasPart" refines "relation"; "created" refines "date").
- Rationale:
- DCTERMS is the currently maintained DCMI standard.
- As Sarah Shreeves recently commented:
"I want to strongly urge the group to look at conforming with DCMI terms (http://dublincore.org/documents/dcmi-terms/) - even if we can't conform to the vocabulary, etc, this is the most up to date and current form of the namespace. If we use the dc qualifiers document we will be perpetuating the same problem, IMO. I think we can, as Tim suggests, have a graceful path forward. I will admit that a real part of my fear of just moving to DC Qualified is that DSpace--in terms of metadata--will continue to be seen as out of touch with where much of the metadata world is headed." - Also, from http://dublincore.org/documents/dces/:
"Since 1998, when these fifteen elements [dc: namespace] entered into a standardization track, notions of best practice in the Semantic Web have evolved to include the assignment of formal domains and ranges in addition to definitions in natural language. Domains and ranges specify what kind of described resources and value resources are associated with a given property. Domains and ranges express the meanings implicit in natural-language definitions in an explicit form that is usable for the automatic processing of logical inferences. When a given property is encountered, an inferencing application may use information about the domains and ranges assigned to a property in order to make inferences about the resources described thereby.Since January 2008, therefore, DCMI includes formal domains and ranges in the definitions of its properties. So as not to affect the conformance of existing implementations of "simple Dublin Core" in RDF, domains and ranges have not been specified for the fifteen properties of the dc: namespace (http://purl.org/dc/elements/1.1/). Rather, fifteen new properties with "names" identical to those of the Dublin Core Metadata Element Set Version 1.1 have been created in the dcterms: namespace (http://purl.org/dc/terms/). These fifteen new properties have been defined as subproperties of the corresponding properties of DCMES Version 1.1 and assigned domains and ranges as specified in the more comprehensive document "DCMI Metadata Terms" [DCTERMS].Implementers may freely choose to use these fifteen properties either in their legacy dc: variant (e.g., http://purl.org/dc/elements/1.1/creator) or in the dcterms: variant (e.g., http://purl.org/dc/terms/creator) depending on application requirements. The RDF schemas of the DCMI namespaces describe the subproperty relation of dcterms:creator to dc:creator for use by Semantic Web-aware applications. Over time, however, implementers are encouraged to use the semantically more precise dcterms: properties, as they more fully follow emerging notions of best practice for machine-processable metadata."
- As Sarah Shreeves recently commented:
- DCTERMS is the currently maintained DCMI standard.
- Examples:
- The ultimate goal, as described below, is to implement full compliance with DCTERMS, which would involve supporting the standard's range and domain values. This goal, however, is not possible with the current DSpace data model. For now, DCTERMS could be provided as a flat schema. Unlike our proposal for the updated 'dc' (QDC) schema, the DCTERMS schema will not be an update of what currently ships with DSpace but a whole new set of properties. Some of these terms, however, are easily mapped between the existing 'dc' (QDC) schema. For example, dc.date.created maps to dcterms:created. dc.format maps to dcterms:format. dc.date.updated maps to dcterms:modified.
- Some of these mappings remain to be decided and finalized. For example, DCTERMS provides a controlled list of syntax and vocabulary encoding schemes. QDC and "DCMI Terms" have often designated vocabulary and syntax encoding specifications as qualifiers (e.g., dc.subject.mesh, dc.identifier.uri). If we flatted DCTERMS, do we similarly extend with qualifiers (e.g., dcterms:subject.mesh)?
- A preliminary mapping can be found here: https://wikidocs.duraspacegoogle.orgcom/download/attachments/32478705/DCAT+QDC+preliminary+%28posted+to+DCAT+8.15.2012%29.xlsxspreadsheet/ccc?key=0AgU-htsSmo31dEtaM1M1Q2E1NlRxNG11ZHFrSkMxNFE#gid=0
- Background:
- Lockdown schemas offering migratory tools to pull out local customizations and push into new local schema. Make it possible but not easy to delete or edit elements in 'dc' (QDC) and DCTERMS schemas. Continue to enable the addition of qualifiers in the 'dc' (QDC) schema.
- For staging purposes, we recommend that DSpace ship with 3 registries, to support ultimate migration to DCTERMS, allow for the continuing use of QDC, and standardize namespaces by pushing local customizations not compliant with QDC or DCTERMS into a local schema.:
- 1) 'dc' (QDC) - which will be an update of the current default 'dc' schema, and will be set as the default metadata schema
- 2) 'dcterms' (DCTERMS) - which will be an optional metadata schema, ultimate goal of replacing 'dc' (QDC) at some point in the future
- 3) Local schema - which would ship with some elements migrated out of 'dc' because not compliant with QDC, and enabled for the purpose of local customizations
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