1. Digital Preservation Seminar
Using MPEG-21 DIDL to Represent Complex Digital Objects in the Los Alamos National Laboratory Digital Library
Authors:
Jeroen Bekaert, Patrick Hochstenbach & Herbert Van de Sompel
Presenter:
Rabia Haq
1/14/2019
Digital Preservation Seminar

2. Digital Preservation Seminar
Introduction
Digital Objects in the LANL Repository
MPEG-21 Digital Item Declaration Language - DIDL
Use of MPEG-21 DIDL to represent LANL Repository
Conclusion
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Digital Preservation Seminar

3. Digital Objects at LANL
XML-packaging required that supports
Datastreams of various media-types
Secondary data – metadata supporting
- discovery
- digital preservation
- rights management
Persistent Identifiers
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4. Digital Preservation Seminar
MPEG-21 DIDL
A DIDL complex object – Digital Item Declaration (DID)
Each received data item is a DID
All DIDs wrapped into one large XML file
Note: data items are enclosed within <didl:Container> tags
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5. Digital Preservation Seminar
DIDL – Data Model
Container <didl:Container>
Item <didl:Item>
Component <didl:Component>
Resource <didl:Resource>
Descriptor <didl:Descriptor>
LANL defined a DIDL profile conforming to
- MPEG-21 DIDL Schema &
- self-defined Schematron Schema
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Digital Preservation Seminar

6. Digital Preservation Seminar
DIDL – Data Model
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Figure 1 from Bekert, Hochstenbach, Sompel

7. Digital Preservation Seminar
Descriptors
Provide flexibility to the Data Model
Associated with parent entity
Convey secondary information such as
- Identification Information -MPEG-21 Part 3 : DII
- Processing Information -MPEG-21 Part 10: DIP
- Rights Information MPEG-21 Part 5: REL/
Part 4 : IPMP
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Digital Preservation Seminar

8. DII – Digital Item Identification
Descriptors used to assign persistent identifiers to all entities
- Container, Item, Component,
Descriptor
<dii:Identifier>
Important, as the DIDL profile is id-centric
Terry Harrison mentioned that a data item is useless without any code, or processing Item to access that data item. The PI serves that purpose. Good from a digital preservation point of view.
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Digital Preservation Seminar

9. Digital Preservation Seminar
DII - example
<didl:Item> <didl:Descriptor>   <didl:Statement mimeType="text/xml;
charset=UTF-8">     <dii:Identifier
xmlns:dii="urn:mpeg:mpeg21:2002:01-DII- NS">        urn:isbn: </dii:Identifier>     </didl:Statement>   </didl:Descriptor>     … </didl:Item>
dii:Identifier (Item level)
Table 2 from Bekert, Hochstenbach, Sompel
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Digital Preservation Seminar

10. DIP – Digital Item Processing
Provides architecture for disseminating DIDs
New Item introduced – Processing Item (PI)
- <dip:…>
ObjectType – link between entity and Processing Item
<dip:ObjectType> value = <dip:Argument> of PI
An entity can have multiple ObjectTypes
A PI can bind to more than one entity
1/14/2019
Digital Preservation Seminar

11. Digital Preservation Seminar
DIP - example
<didl:Item> … Content
<!-- ObjectType of Item -->
<didl:Descriptor>     <didl:Statement mimeType="text/xml; charset=UTF-8">       <dip:ObjectType xmlns:dip="urn:mpeg:mpeg21:2002:01-DIP-NS">       urn:my:Argument</dip:ObjectType>     </didl:Statement>   </didl:Descriptor>
…</didl:Item> Processing Item
<didl:Item>
 …    
<didl:Descriptor>
<!-- Argument of processing method -->
<didl:Statement mimeType="text/xml; charset=UTF-8">   <dip:Argument xmlns:dip="urn:mpeg:mpeg21:2002:01-DIP-NS">       urn:my:Argument</dip:Argument>   </didl:Statement>
</didl:Descriptor>
<didl:Resource mimeType="…">…Link to processing code…</didl:Resource>  …
</didl:Item>
Excerpt from Table 3 from Bekert, Hochstenbach, Sompel
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Digital Preservation Seminar

12. REL – Rights Expression Language
Descriptor associates rights expressions with DIDs and contained entities
MPEG-21 Intellectual Property Management and Protection (IPMP)
- provides tools to enforce rights
expressions declared by REL
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Digital Preservation Seminar

13. Digital Preservation Seminar
REL/IPMP - example
<didl:Item>     …
<didl:Descriptor> <didl:Statement mimeType="text/xml; charset=UTF-8">   <r:license xmlns:r="urn:mpeg:mpeg21:2003:01-REL-R-
NS">   <!-- optionally, specific rights can be added here.-->     <r:otherInfo>       <dc:rights
xmlns:dc="         Copyright 2003; American Physical
Society</dc:rights>
        </r:otherInfo>     </r:license>   </didl:Statement>
</didl:Descriptor>     …
</didl:Item>
Table 4 from Bekert, Hochstenbach, Sompel
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Digital Preservation Seminar

14. MPEG-21 DIDL usage at LANL – DIDL Profile
LANL DIDs compliant with both MPEG21 and self-defined schemas
types of DIDs in examples
- a PDF technical Report
- a MARC record
- an XML representation of the MARC record
All three considered independent data items
Relationships established through self-defined Descriptors
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15. DIDL profile DID structure
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Figure 2 from Bekert, Hochstenbach, Sompel
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16. LANL’s usage of Descriptors
Identifiers – mandatory for all DIDs
PlaceHolders for Processing Items
Defining Relationships
Creation Date
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Identifiers
<dii:Identifier>
Two types of DID Identifiers
- DID identifier
of entities – Container, Item, Processing Item…
DID identifier :
urn:uuid:10ba6842-ec45-3b19-8kub-
hy8ff58c58a8b
- Content identifier
of content - technical reports, MARC records...
Technical Report Identifier:
urn:bar:
Identifiers from Table 5 from Bekert, Hochstenbach, Sompel
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Digital Preservation Seminar

18. PlaceHolders for Processing Items
A change in Processing Item of an entity requires a DIDL update.
Each update results in a new DIDL version
Inappropriate for LANL’s static data items
PLaceHolders for Processing Items
- <diph:PlaceHolder>
- PlaceHolders replaced with ObjectType and Processing Item during dissemination of DID
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19. Digital Preservation Seminar
Relationships
Descriptor to express relationships between entities
- Container, Item, Component …
- entities and resources external to that entity
A Digital Item Relations XML – Namespace
- <dir:Relations>
Contains Resource Descriptive Framework (RDF) statements, “isDerivationOf”, “isPartOf”, “isTranslationOf”, “isDescriptiveMetadataOf”, etc.
more statements can be defined as required
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Digital Preservation Seminar

20. Relationships - example
<didl:Item> …
<didl:Descriptor>
<didl:Statement mimeType="text/xml; charset=UTF-8"> <dir:Relations xmlns:dir="     <rdf:RDF xmlns:rdf="                 xml:base="urn:uuid:10ba6842-ec45-3b19-8kub-hy8ff58c58a8b">       <rdf:Description rdf:about="#//didl:Item[1]”>
        <a:isPartOf xmlns:a="           <rdf:Description rdf:about="info:sid/library.lanl.gov:lanl-opac">           <b:hasType xmlns:b="            rdf:resource="          </rdf:Description>          </a:isPartOf>        <rdf:Description>        <rdf:Description rdf:about="#//didl:Item[1] ">          <b:isDescriptiveMetadataOf   xmlns:b="
rdf:resource="#//didl:Item[2] "/>
       </rdf:Description>     </rdf:RDF>   <dir:Relations> </didl:Statement>
</didl:Descriptor>     …
</didl:Item> Table 8 from Bekert, Hochstenbach, Sompel
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Creation Date
Descriptor to contain creation datetime of each entity – Container, Item, Component
Digital Item Date Time Namespace
<didt:Created>
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Creation Date
<!-- Creation-datetime of Container -->
<didl:Descriptor>
<didl:Statement mimeType="text/xml; charset=UTF-8">   <didt:Created xmlns:didt=" 09/MPEG-21/DIDT">     T21:51:01Z</didt:Created> </didl:Statement>
</didl:Descriptor>
Excerpt from Table 9, from Bekert, Hochstenbach, Sompel
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23. Digital Preservation Seminar
Conclusion
LANL utilized MPEG-21 DIDL Data Model
- Container, Item, Component, Resource,
Descriptor
Utilized flexibility provided by Descriptors
Defined Namespaces for
- Identifiers – DII
- PlaceHolders for Processing Items
- Rights Expressions
- Creation Date and Time
1/14/2019
Digital Preservation Seminar

24. Example – Item hierarchy
…<didl:Item>
Descriptor for dii:Identifier content identifier of item
Descriptor for didt:Created Creation Date of item
Descriptor for defining relationships of item
<didl:Component>
Descriptor for PlaceHolder of datastream
Description for didt:Created Creation Date of datastream
didl:Resource containing actual datastream
didl:Recource containing datastream reference
</didl:Component>
</didl:Item> …
Excerpt from Appendix A, from Bekert, Hochstenbach, Sompel
1/14/2019
Digital Preservation Seminar