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Confession
• I don’t know much about identifiers• I do know what I could do with them• Two communities
– Those who want to define the functional specifications of persistent identifiers and their resolvers
– Those who don’t care about that, but want to do things that are only possible if identifiers work in the background
Persistent Identifiers
• Why?– Benefits
• To the owner • To others
• How?– Technologies– Processes
Imagine…
• You have just been asked to create a new medical course (Brain Surgery 101)
• A colleague in another university passes you the identifier of a reading list she has used
• You locate the list and find a useful learning object• You use a web service to find the most current version of the
learning object• You use another web service to search for every course in
which that learning object is used• You use another web service to locate secondary metadata
(reviews, comments, annotations, usage statistics) for the object and the courses
• You use another web service to differentiate the right (terms and conditions of use) of the courses and all their components
• You build a course based on high-quality, well-used, elements of different courses which are free and whose use is not time-limited, adding your own material
• You make your own course available
Previous work
• ERPANet: Persistent identifiers– Electronic Resource Preservation and Access
Network– Cork, 17-18th June 2004– Surveyed identifiers and their users
• CETIS: Learning object identifiers– Centre for Educational Technology
Interoperability Standards– London, 21 Oct 2003– Surveyed uses for identifiers
ERPANet CETIS
• Publishers• Archives• Libraries• Repositories
• Mechanisms• Persistence• Resolvability• Tools
• E-learning• Self-publishing• Repositories• Federations of
repositories
• Uses• Format• Actionability• Persistence
Identifiers needed for
• Digital material– E-publications– Learning objects– Media object– Data – Metadata
• Non-digital material– Books – Journals– People– Organisations– Locations– Events
Stakeholders
• Libraries• Publishers• Archives• Repositories• Object creators• Object users
Just do it
• A system needs identifiers, choose one, and make it work
• A community needs identifiers– Many independent decisions-makers– Many proprietary and non-proprietary
systems– Some degree of local autonomy needed– How are decisions reached– How are processes standardised
• Lessons from ISBN?
CETIS Metadata SIG list
• “Do I need identifiers for both objects and metadata in my repository”
• “It depends on what you want to use them for”
• “You shouldn’t need to worry too much, appropriate identifiers should be generated automatically by your repository”
Focus on learning objects
• Is a learning object complicated?– Granularity– Versions– Relating metadata to entities– Relating entities to entities– Dynamic entities
• Complications similar to scientific data
Create and Deposit
Metadata
REPOSITORY Z
rdn.ac.uk
Metadata
Entity-identifierrdn.ac.uk/z-67890
Metadata-identifierrdn.ac.uk/z-meta-1234
New version
Metadata
REPOSITORY Z
Metadata
Metadata
Entity-identifierrdn.ac.uk/z-62847
Metadata-identifierrdn.ac.uk/z-meta-1367
Relation-identifierisVersionOf
rdn.ac.uk/z-67890
rdn.ac.uk
Metadata
Entity-identifierrdn.ac.uk/z-67890
Metadata-identifierrdn.ac.uk/z-meta-1234
Relation-identifierhasVersion
rdn.ac.uk/z-62847
Duplicate in another repository
REPOSITORY Z
Metadata
rdn.ac.uk
Metadata
REPOSITORY X
Metadata
Entity-identifierrdn.ac.uk/z-67890
Metadata-identifier
bath.ac.uk/z-meta-set23
bath.ac.uk
New entry in metadata catalogue
REPOSITORY Z
Metadata
Metadata
CATALOGUE A
Metadata
Entity-identifierrdn.ac.uk/z-67890
Metadata-identifier
ltsn.ac.uk/217461 rdn.ac.uk
ltsn.ac.uk
Aggregate and store
REPOSITORY Z
rdn.ac.uk
Metadata
Metadata
REPOSITORY V
MetadataMetadata
MetadataMetadata
Metadata
gla.ac.uk
Metadata
Entity-identifiergla.ac.uk/ab.123.x
Metadata-identifiergla.ac.uk/cf.657.m
Relation-identifierhaspart
rdn.ac.uk/z-67890
Metadata
Entity-identifierrdn.ac.uk/z-67890
Metadata-identifiergla.ac.uk/ce.311.m
Relation-identifierispartof
gla.ac.uk/ab.123.x
Move aggregation - disaggregate
rdn.ac.uk
REPOSITORY Z
Metadata
Metadata
REPOSITORY V
Metadata
Metadata
Entity-identifiergla.ac.uk/ab.123.x
Metadata-identifierrdn.ac.uk/z-meta-3999
Relation-identifierhaspart
rdn.ac.uk/z-67890 gla.ac.uk
Multiple metadata for one LO
REPOSITORY Z
Metadata
rdn.ac.uk
Grant Cocks, Simulacra
Metadata
CATALOGUE A
Metadata
Metadata
Entity-identifierrdn.ac.uk/z-67890
Metadata-identifierltsn.ac.uk/890
ltsn.ac.uk
Metadata
Entity-identifierrdn.ac.uk/z-67890
Metadata-identifierltsn.ac.uk/891
Multiple resolutions in one LO
Metadata
REPOSITORY Z
rdn.ac.uk
Metadata
Entity-identifierrdn.ac.uk/z-67890
Metadata-identifierrdn.ac.uk/z-meta-1234
locationresolution-low.avi
resolution-medium.aviresolution-high.avi
Gayle Calverley, U of Manchester
Metadata
Metadata
Metadata
REPOSITORY Z
ed.ac.uk
Metadata harvesting
Phil Barker, CETIS
REPOSITORY Z
rdn.ac.uk
Metadata
Metadata
Metadata
The HUB
ltsn.ac.uk
Metadata
REPOSITORY X
bath.ac.uk
Metadata
Metadata
Metadata
Metadata
Metadata
Metadata
Metadata
MetadataMetadata
Metadata
Metadata
Metadata
Metadata
Metadata
MetadataOAI-PMH
Some duplicate objectsbut not duplicate metadatarecords – different descriptions
Multilingual, multibrand, multiversion
Metadata
Metadata
Metadata
REPOSITORY Z
c.com
REPOSITORY Z
b.com
Metadata
Metadata
Metadata
Metadata
REPOSITORY X
a.com
Metadata
Metadata
Metadata
Metadata
Metadata
Metadata
Metadata
MetadataMetadata
Metadata
Metadata
Metadata
Metadata
Metadata
Metadata
Dan Rehak, Carnegie-Mellon
Metadata
PreferencesSearches based on:Object identifierBrand styleLangauge (LIP)
BrandStyle
Issues
• Don’t define the solution until you have defined the problem
• Defining processes for using identifiers is as/more important than choosing identifiers
• Many, diverse “publishers”• Cost/effort at point of issue• What needs an identifier (ephemeral –
permanent)?• Properties of identifiers (Uniqueness, Persistence,
Action)• Automatically generated when needed• Services built on use of identifiers• Does it matter which identifier?
OpenURL
