PREMIS Implementation at The Royal Library of Denmark by Eld Zierau.
Implementation of PREMIS in METS Rebecca Guenther Sr. Networking & Standards Specialist, Library of...
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Transcript of Implementation of PREMIS in METS Rebecca Guenther Sr. Networking & Standards Specialist, Library of...
Implementation of PREMIS in METS
Rebecca GuentherSr. Networking & Standards Specialist, Library of [email protected]
PREMIS Implementation FairSan Francisco, CAOctober 7, 2009
METS records the (possibly hierarchical) structure of digital objects, the names and locations of the files that comprise those objects, and the associated metadata
A METS document may be a unit of storage (e.g. OAIS AIP) or a transmission format (e.g. OAIS SIP or DIP)
METS is extensible and modular METS uses the XML Schema facility for combining
vocabularies from different Namespaces The METS Editorial Board has endorsed PREMIS as an
extension schema Many institutions trying to use PREMIS within the METS
context
Structure of a METS file
ArchivalInformation
Package
DescriptiveInformation
ContentInformation
described by
derived from
delimited by
identifies
further described by
RepresentationInformation
DataObject
Semantics
ProvenanceInformation
ReferenceInformation
FixityInformation
ContextInformation
PreservationDescriptionInformation
PackagingInformation
Structure described by
<dmdSec>
<fileGrp>
<techMD>
<METS>
<digiProvMD><sourceMD>premis:event<techMD>
<structMap>
MODSMARCXML
DC
premis:object
metsRightspremis:rights
<rightsMD>
File formats premis:objecttextMD
MIX
<file>
<amdSec>
OAIS, METS and PREMIS
Legend
Black Arial = OAISRed Times New Roman = METS Primary SchemaBlue Times New Roman Italics = Extension Schema
<mdRef>
METS extension schemas
“wrappers” or “sockets” where elements from other schemas can be plugged in
Provides extensibility Uses the XML Schema facility for combining vocabularies from
different Namespaces Endorsed extension schemas:
• Descriptive: MODS, DC, MARCXML• Technical metadata: MIX (image); textMD (text)• Preservation related: PREMIS
Why do we need guidelines for using PREMIS with METS?
Contents of each information package may vary depending on its function within a repository
Need to determine how to include representation metadata and associate it with package components
PREMIS data entities (objects, events, rights, agents) do not map perfectly to METS categories for representation metadata (techMD, digiProvMD, rightsMD, sourceMD)
There are redundant elements between the two standards Both have extensibility mechanisms Flexibility of both standards requires implementation
choices
Development of Guidelines for Using PREMIS with METS for Exchange PREMIS in METS Guidelines Working Group
• Consists of PREMIS and METS experts• Focuses on the METS document as a mechanism of exchange
of digital objects and their metadata (SIP or DIP)• Facilitates communication when internal requirements and
technical environments vary Tension between flexibility and being prescriptive to facilitate
interoperability• Consider usage scenarios• If a SIP it may get unwrapped and stored in different structures• If a DIP it is converted from internal structures to PREMIS• A more liberal approach is possible for a SIP than a DIP
Establishing guidelines, a METS profile, and exampleshttp://www.loc.gov/standards/premis/guidelines-premismets.pdf
Implementation issues in using PREMIS with METS
Location of PREMIS metadata within METS documents Whether to record elements redundantly if they occur in
both PREMIS and METS Relationship of different structural metadata mechanisms in
PREMIS and METS How to record PREMIS Agent entities in METS documents Use of identifiers to link elements in PREMIS and METS How to record elements that are also part of a format
specific technical metadata schema (e.g. MIX)
Some recommendations from Guidelines
METS sections• Use Object in techMD or digiProvMD• Use Event in digiProvMD• Use Rights in rightsMD• Use Agent in digiProvMD or rightsMD
PREMIS Container -- use only if keeping all PREMIS metadata together. Do not use if separating PREMIS metadata into different amdSec subelements
PREMIS and METS redundancies -- Choosing which options to use is an implementation decision, document in profile e.g. METS <size> element attributes and subelements of <objectCharacteristics> in PREMIS
Recommendations (cont.)
Structural relationship elements -- use the METS structMap to record structural relationships, use PREMIS relationship elements to record preservation and derivation relationships and structural if desired
ID/IDREF and PREMIS identifier elements -- use METS ID/IDREF mechanisms, best practices for using these ID/IDREF mechanisms apply
Use PREMIS extensibility mechanism for format specific technical metadata
Document decisions in METS profiles
<fileSec><fileGrp><file ID="FID1" SIZE="184302" ADMID="TMD1PREMIS TMD1MIX DP1EVENT
DP1AGENT“ CHECKSUM="4638bc65c5b9715557d09ad373eefd147382ecbf" CHECKSUMTYPE="SHA-1">
<FLocat LOCTYPE="OTHER" xlink:href="BXF22.JPG" /></file></fileGrp></fileSec><techMD ID="TMD1PREMIS"> <mdWrap MDTYPE="PREMIS"> <xmlData>
<premis:object > <objectCharacteristics> <fixity> <messageDigestAlgorithm>SHA-1 </messageDigestAlgorithm> <messageDigest>4638bc65c5b9715557d09ad373eefd147382ecbf
</messageDigest> <messageDigestOriginator>EchoDep/messageDigestOriginator> </fixity> <size>184302</size> </objectCharacteristics>
Elements defined in both METS and PREMIS:• METS: Checksum, Checksumtype
• attribute of <file>• not repeatable
PREMIS: fixity• also includes messageDigestOriginator• allows multiples
<fileSec><fileGrp><file ID="FID1" ADMID="TMD1PREMIS DP1EVENT DP1AGENT“
MIMETYPE="image/jpeg" <FLocat LOCTYPE="OTHER" xlink:href="BXF22.JPG"/></file></fileGrp></fileSec>
<techMD ID="TMD1PREMIS“ <mdWrap MDTYPE="PREMIS"> <xmlData> <premis:object> <objectCharacteristics> <format> <formatDesignation> <formatName>image/jpeg</formatName> <formatVersion>1.02 </formatVersion> </formatDesignation></format> </objectCharacteristics>Elements defined both in METS and PREMIS:• METS: MIMETYPE
• attribute of <file>• optional
PREMIS: <format> • more granular; includes name and version (although name may be MIMETYPE)• mandatory
<fileSec> <fileGrp> <file ID="FID1" ADMID="TMD1PREMIS TMD1MIX DP1EVENT DP1AGENT"><techMD ID="TMD1PREMIS"> <linkingEventIdentifier> <linkingEventIdentifierType>ECHODEP Hub Event </linkingEventIdentifierType> <linkingEventIdentifierValue>echo12345</linkingEventIdentifierValue> </linkingEventIdentifier><digiprovMD ID="DP1EVENT"> <premis:event> <eventIdentifier> <eventIdentifierType>ECHODEP Hub Event</eventIdentifierType> <eventIdentifierValue>echo12345 </eventIdentifierValue> </eventIdentifier> <eventType>ingestion</eventType> <eventDateTime>2006-05-02T15:12:53 </eventDateTime></event>
Elements defined both in METS and PREMIS METS ID/Idref: used to associate metadata in different sections and for different
files PREMIS identifiers: explicit linking between entity types
<structMap TYPE=“physical”> <div ORDER="1" TYPE="text"> <:fptr FILEID="FID9"/> <div ORDER="1" TYPE="page" LABEL=" Page [1]"> <fptr FILEID="FID1"/></mets:div> <div ORDER="2" TYPE="page" LABEL=" Page [2]"> <fptr FILEID="FID2"/></mets:div> </div>
<relationship> <relationshipType>structural</relationshipType> <relationshipSubType>is sibling of </relationshipSubType> <relatedObjectIdentification> <relatedObjectIdentifierType>UCB</relatedObjectIdentifierType> <relatedObjectIdentifierValue>FID2</relatedObjectIdentifierValue> <relatedObjectSequence>1</relatedObjectSequence>
Elements defined both in METS and PREMIS: METS: structMap
• details structural relationships and is the heart of the METS document• hierarchical, so may be more expressive than PREMIS semantic units• links the elements of the structure to content files and metadata
PREMIS: <relationship> • details all kinds of relationships, including structural• data dictionary says that implementations may record by other means
Some METS profiles with PREMIS
UCSD simple and complex object UC Berkeley ECHO Dep Generic METS Profile for Preservation and Digital
Repository Interoperability LC Profile for Recorded Events Australian METS Profile TIPR … many others
Additional changes to Guidelines
Make extensibility mechanism consistent with METS• significantPropertiesExtension• objectCharacteristicsExtension• creatingApplicationExtension• environmentExtension• signatureInformationExtension• eventOutcomeDetailExtension• rightsExtension
Additional changes to Guidelines (cont.)
Add the same elements and attributes as in METS to PREMIS extension elements in schema and data dictionary• mdRef, mdWrap• binData, xmlData• Attributes: ID, LABEL, MDTYPE, MIMETYPE, SIZE,
CREATED, CHECKSUM, CHECKSUMTYPE
Allow URI or string for MDTYPE Add use cases/examples to illustrate choices made Clarify structural relationships
Implementing an Exchange Standard
PREMIS Implementation Tool• Some tools documented on the PREMIS website
http://www.loc.gov/standards/premis/tools_for_premis.php
• PiM tool developed by Florida Center for Library Automation
• Further work to generate metadata from digital files in PREMIS elements