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Presented at the program: Law Libraries and the Semantic Web, Monday, 8:30-10:00 at the American Association of Law Libraries in Boston, MA.
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Law Libraries and Linked Data Vocabularies
Thriving in an Open World
AALL Boston 7/23/2012 2
Linked Data is About Machines
Traditional cataloging considers identification via text adequate (for physical things mostly) A ‘record’ aggregates statements, but
the identity of the resource being described is often squishy (a title? Title plus author? ISBN?)
Digital identity must be significantly clearer (a URI/URL?) because immediate access is expected
Our entry into the digital world is forcing us to look more carefully at our practices
AALL Boston 7/23/2012 3
Linked Data is Inherently Chaotic
Requires creating and aggregating data in a broader context There is no one ‘correct’ record to be made
from this, no objective ‘truth’ This approach is different from the
cataloging tradition BUT, the focus on vocabularies is one we can
work with In the SemWeb world vocabularies are
more complex than the thesauri we know
AALL Boston 7/23/2012 4
Model of ‘the World’ /XML XML assumes a 'closed' world (domain),
usually defined by a schema: "We know all of the data describing this
resource. The single description must be a valid document according to our schema. The data must be valid.”
XML's document model provides a neat equivalence to a metadata 'record’
AALL Boston 7/23/2012 5
Model of ‘the World’ /RDF RDF assumes an 'open' world:
"There's an infinite amount of unknown data describing this resource yet to be discovered. It will come from an infinite number of providers. There will be an infinite number of descriptions. Those descriptions must be consistent."
RDF's statement-oriented data model has no notion of 'record’ (rather, statements can be aggregated for a fuller description of a resource)
AALL Boston 7/23/2012 6
RDVocab: Most Important Goals
Bridge the XML and RDF worlds Ensure ability to map between RDA and
other element sets Provide a sound platform for extension of
RDA Vocabularies into new and specialized domains
Consider methods for expressing AACR2 structures in technical ways to ease the pain of transition to RDA
AALL Boston 7/23/2012 7
RDVocab Structure, Simplified RDA Properties declared in two separate
hierarchies: An ‘unconstrained’ vocabulary, with no explicit
relationship to FRBR entities A subset of classes, properties and
subproperties with FRBR entities as ‘domains’ Pros: retained usability in or out of
libraries; better mapping to/from non-FRBR vocabularies
Cons: still seems too complex to many SemWeb implementers (many using BIBO)
AALL Boston 7/23/2012 8
Why Unconstrained Properties? The ‘bounded’ properties should be seen as the
official JSC-defined RDA Application Profile for libraries What’s still lacking is the addition of the necessary
constraints: datatypes, cardinality, associated value vocabularies
Extensions and mapping should be built from the unconstrained properties Unconstrained vocabularies necessary for use in
domains where FRBR not assumed or inappropriate Mapping from vocabularies not using the FRBR model
directly to ones that do (and back) creates serious problems for the ‘Web of Data’
AALL Boston 7/23/2012 9
Property (Generalized, no FRBR relationship)
Subproperty (with relationship to one FRBR entity)
FRBR Entity
SemanticWeb
Library ApplicationsThe Simple Case:
One Property-- One FRBR Entity
AALL Boston 7/23/2012 10
Property (Generalized, no FRBR relationship)
Subproperty (with relationship to one FRBR entity)
Subproperty (with relationship to one FRBR entity)
FRBR Entity
FRBR Entity
SemanticWeb
Library ApplicationsThe Not-So-Simple Case: One Property—more than
One FRBR Entity
AALL Boston 7/23/2012 11
Roles: Attributes or Properties? In 2005, the DC Usage Board worked with LC to
build a formal representation of the MARC Relators so that these terms could be used with DC This work provided a template for the
registration of the role terms in RDA (in Appendix I) and, by extension, the other RDA relationships
Role and relationship properties are registered at the same level as elements, rather than as attributes (as MARC does with relators, and RDA does in its XML schemas)
AALL Boston 7/23/2012 12
Aggregated Statements
RDA (and MARC 21) include pre-coordinated, aggregated statements that have traditionally been handled as a whole, ex.: Publication, Distribution, Manufacture and Production statements, etc. These were originally pulled together for the efficient
display on catalog cards Some users will prefer to deal with the issue at the
display level, by using separate properties and configuring the display to manipulate the order
To deal with retrospective, transitional and (some) prospective needs, we must address the desire to continue this practice
AALL Boston 7/23/2012 13
Aggregated Statement (no domain or range)
Aggregated Statement Subproperty
Range: RDA Syntax Encoding Scheme (Subclass of RDF Datatype)
Dom
ain
: FRB
R E
ntity
Range: [Specific] Encoding Scheme (Subclass)
General Property (no domain or range)
Subproperty
Pre-coordinated Statements: Structure
AALL Boston 7/23/2012 14
Publication Statement (no domain or range)
Publication Statement (Manifestation)
Range: RDA Syntax Encoding Scheme (Subclass of RDF Datatype)
Dom
ain
: M
anife
statio
n
Range: Publication Statement Encoding Scheme (Subclass)
Place of publication (no domain or range)
Place of publication (Manifestation)
Pre-coordinated Statements: Example
AALL Boston 7/23/2012 15
Vocabulary Extension
The inclusion of unconstrained properties provides a path for extension of RDA into specialized library communities and non-library communities They may have a different notion of how FRBR
‘aggregates’ (For example, a colorized version of a film may be viewed as a separate work)
They may not wish to use FRBR at all They may have additional, domain-specific
properties to add, that could benefit from a relationship to the RDA properties
AALL Boston 7/23/2012 16
RDA:adaptedAs
RDA:adaptedAsARadioScript
hasSubprope
rty
AALL Boston 7/23/2012 17
RDA:adaptedAs
RDA:adaptedAsARadioScript
KidLit:adaptedAsAPictureBook
hasSubproperty
hasSubprope
rty
Extension using Unconstrained Properties
AALL Boston 7/23/2012 18
RDA:adaptedAs
RDA:adaptedAsARadioScript
KidLit:adaptedAsAPictureBook
hasSubproperty
hasSubprope
rty
KidLit:adaptedAsAChapterBook
hasS
ubprop
e
rty
Extension using Unconstrained Properties
AALL Boston 7/23/2012 19
Mapping
Building relationships between vocabularies is not necessarily a proprietary activity or tied to particular applications (not ‘crosswalking’ as we have understood that term)
http://MARC21rdf.info provides a beginning point for mapping library data that is easily shared and modified to meet a variety of needs
New approaches go beyond ‘sameAs’ and suggest the potential for more granular, nuanced relationships
Mapping in this context retains the original data ‘as is’ and provides a view through the lens of another structure (with minimal loss of richness)
AALL Boston 7/23/2012 20
AALL Boston 7/23/2012 21http://marc21rdf.info
AALL Boston 7/23/2012 22
Property Detail: Relator codes
http://marc21rdf.info/elements/1XXM1000_4
Tag: 100 (Main entry-Personal Name)
Ind2: # (no caption)Sub: 4 (Relator code)
AALL Boston 7/23/2012 23
RDF graph of 00X mapping pattern for an attribute with more than one valueand no significance in the order of values
AALL Boston 7/23/2012 24
Partial RDF graph of 00X mapping pattern for two or more attributes withmore than one value and significance in the order of values
The Bottom Line
Our big investment is (and has always been) in our data, not our systems
Over many changes in format of materials, we’ve always struggled to keep our focus on the data content that endures, regardless of differences in data management strategy or presentation format
We have made good progress in moving towards our common future, but we can’t be afraid to change, or afraid to fail
AALL Boston 7/23/2012 25
Thank you! Questions?
Contact info: [email protected]
Metadata Matters: http://managemetadata.com/blog
AALL Boston 7/23/2012 26