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Fedora migration considerations
Juliet L. HardestyMetadata Analyst, Indiana University
Open Repositories, June 15, 2016
Fedora 3 diagram key
Repository object
Structural metadata datastream
Descriptive metadata datastream
Other metadata datastream
Indiana University President's Office records, 1937-1962. Subject files, 1937-1962. Aeons, Board of, 1939-1940.
Fedora 3 - documents
VAA8877-06169 Fedora DC
RELS-EXT METS
VAA8877-U-03624 Fedora DC
RELS-EXT PDF
VAA8877-U-03624-001Fedora
DCRELS-EXT MASTER
Derivatives
MASTER-MIX
Folder
Document in folder
Page in document
isMemberOfCollection
isPartOf
isPartOf
Portable soft drink stand at Bowling Green
Fedora 3 - images
P02668 Fedora DC
RELS-EXT METSPURL
Redirect
isMemberOfCollection
DCMODS
Image
[Program, 2013-2014, no. 117]
Fedora 3 – time-based media
avalon:22187Fedora
DCRELS-EXT MODSRIGHTS
SECTIONS TECH/DISPLAY
WORKFLOW
Fedora DC
RELS-EXT
STRUCTURE MATTERHORN
avalon:22191
Fedora DC
RELS-EXT
STRUCTURE MATTERHORN
Item
CD 1 CD 2
avalon:22189
isMemberOfCollection
TECH/DISPLAY
TECH/DISPLAY
isPartOf
isPartOf
Focusing on Fedora 3 structure
• RELS-EXT defines structure going up• METS or special datastreams required to
define structure going down• All in XML as datastreams on objects that
connect together down to the digital file
https://github.com/duraspace/pcdm/wiki
PortlandCommonDataModel
Document example in PCDM
Wilcox, David and Andrew Woods. “Hands-On: Seeing Fedora 4 Firsthand.” Fedora 4 Training Workshop. Open Repositories 2015.
METS: fileSec
METS: structMap
VAA8877-06169 VAA8877-U-03626 VAA8877-U-03626-page1
filesdocuments pages
VAA8877-U-03626Proxy VAA8877-U-03626-page1Proxythumb.jpg
screen.jpg
large.jpg
pcdm:hasMember
pcdm:hasMember
Fedora 4 structure diagram
http://localhost:8080/fcrepo/rest/VAA8877-U-03625/pages/VAA8877-U-03625-page1Proxy
METS as PCDM in Fedora – SPARQL query
select DISTINCT ?document ?firstPage ?nextPage where {{ <http://localhost:8080/fcrepo/rest/VAA8877-06169> pcdm:hasMember ?document . ?document iana:first ?firstPageProxy . ?firstPageProxy ore:proxyFor ?firstPage . } union { <http://localhost:8080/fcrepo/rest/VAA8877-06169> pcdm:hasMember+ ?page . ?page pcdm:hasFile ?f . ?f ebucore:hasMimeType "image/jpeg"^^xsd:string . ?pageProxy ore:proxyFor ?page . ?pageProxy iana:next ?nextPageProxy . ?nextPageProxy ore:proxyFor ?nextPage . }}
SPARQL query results for structure of folder VAA8877-06169
Transforming METS to PCDM
• Consider structure for collections using METS• fileSec and structMap– @GROUPID, @ID, @FILEID (unique identifiers
from both sections) in combination with <div> structure within structMap can point to grouping and ordering structure for objects
• Migrating easier if identifiers brought over
Considerations for structural metadata
• RELS-EXT in Fedora 3 migrated to Fedora 4• Other structure datastreams are on you to
map• METS – possible to map programmatically but
maybe not in a standard way
Descriptive Metadata - IU
MODS
Fedora 4 options for descriptive metadata: Option 1
• Migration tools– migration-utils– fedora-migrate gem
Neither really takes advantage of Fedora 4/external triplestoreunless original is already RDF; fedora-migrate requires Hydra
Available now, keeps all metadata, nothing lost; can have RDF statements on object if already in RDF (fedora-migrate)
Descriptive metadata to Fedora 4: Option 2
• Map only simple statements to RDF– Minimal descriptive metadata (title, date) or
descriptive metadata indexed for discovery (title, date, creator, type, subject, genre, language)
– Use ontologies that allow for simple statements
X X XNot MODSRDF
Descriptive metadata to Fedora 4: Option 2
• Map only simple statements to RDF– Minimal descriptive metadata (title, date) or
descriptive metadata indexed for discovery (title, date, creator, type, subject, genre, language)
– Use ontologies that allow for simple statements
Not all metadata is in RDF; changes in ontologies/standards might not be 1:1 match with original
Creates RDF statements in Fedora 4/external triplestore; great option if metadata is DC or other non-hierarchical standard
Descriptive metadata to Fedora 4: Option 3
• Map complex/hierarchical information into external triplestore– All RDF statements (simple and complex) go into
external triplestore but only simple statements are on Fedora 4 object
Cushman photograph – Fedora 4
Cushman photograph – external triplestore
Descriptive metadata to Fedora 4: Option 3
• Map complex/hierarchical information into external triplestore– All RDF statements (simple and complex) go into
external triplestore but only simple statements are on Fedora 4 object
Separates metadata between repository and triplestore,problematic if original metadata not kept in repository
More/all metadata available as RDF; updates easier to managethrough triplestore/Fedora 4 functionality
Descriptive metadata to Fedora 4: Almost Option 4
• MODS “unofficial standard” mapping to RDF– MODS and RDF Group’s mapping/transformation
scenario (http://mods2rdf.xyz/) – Available as conversion code to see MODS mapped
into Fedora 4
Work in progress (not always up, transforming few elements); you might not agree with suggested mappings
Available now to try; might offer standard way to transform MODS similarly across institutions
Considerations for descriptive metadata
• Current state of descriptive metadata• Management needs of Fedora 4• Transform to RDF statements or also to Linked
Data• Decision: keep original descriptive metadata
or not?– At IU, keep original descriptive metadata (for full
item view)
