Content packaging and MPEG-21 DID


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A presentation to the JISC Joint Programmes Meeting, July 2005, Cambridge

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Content packaging and MPEG-21 DID

  1. 1. UKOLN is supported by: Content packaging and MPEG-21 DID Andy Powell, UKOLN, University of Bath [email_address] JISC Joint Programmes Meeting, July 2005, Cambridge a centre of expertise in digital information management
  2. 2. Contents <ul><li>why </li></ul><ul><li>how </li></ul>PPS - I’m not really going to tell you how to use MPEG-21 DID since until 24 hours ago I knew pretty much nothing about it, but many thanks to Jeroen Bekaert and Herbert Van de Sompel of LANL for sharing their presentations and thoughts with me… PS - I’m only going to tell you how using MPEG-21 DID.
  3. 3. Why… <ul><li>… do we need packaging standards? </li></ul><ul><li>because nothing in life is simple! </li></ul><ul><li>applications tend to be built around aggregate objects of one kind or another </li></ul><ul><ul><li>digitised books (multiple parts, i.e. pages) </li></ul></ul><ul><ul><li>learning objects (pathway thru multiple objects) </li></ul></ul><ul><li>even objects that look simple (e.g. an eprint in an eprint archive) turn out to be complex </li></ul><ul><li>we need to exchange ‘complex objects’ </li></ul>
  4. 4. Packaging standards <ul><li>framework for encoding ‘complex objects’ </li></ul><ul><ul><li>containing multiple objects and/or metadata </li></ul></ul><ul><ul><li>may be nested </li></ul></ul><ul><li>often using XML as the encoding framework </li></ul><ul><li>component objects embedded ‘by value’ </li></ul><ul><ul><li>XML fragments or Base64 encoding or … </li></ul></ul><ul><li>or passed ‘by reference’ </li></ul><ul><ul><li>URI </li></ul></ul><ul><li>like all standards, there are plenty to choose from: </li></ul><ul><ul><li>METS, IMS-CP, MPEG-21 DID, XFDU (CCSDS) </li></ul></ul> XFDU = XML Formatted Data Unit CCSDS = Consultative Committee for Space Data Systems
  5. 5. Example 1 – digitised book <ul><li>consider digitised book in a ‘digital library’ </li></ul><ul><li>complex object (book) made up of component parts (pages) </li></ul><ul><li>the object and the parts each have one or more chunks of associated metadata </li></ul><ul><li>parts may be embedded (by value) or linked (by reference) </li></ul><ul><li>typical application: ‘virtual page turner’ </li></ul><ul><li>typical packaging format: METS </li></ul>page book
  6. 6. Example 2 – learning object <ul><li>consider a learning object (whatever that is!) </li></ul><ul><li>complex object made up of one or more parts (other learning objects) </li></ul><ul><ul><li>documents, images, videos, interactive objects, audio files, maps, etc. </li></ul></ul><ul><ul><li>each with IEEE LOM metadata </li></ul></ul><ul><ul><li>some notion of workflow or sequencing ‘thru’ the parts </li></ul></ul><ul><li>typical application: VLE </li></ul><ul><li>typical packaging format: IMS-CP </li></ul>PDF document learning object video multiple- choice test
  7. 7. Example 3 - eprint <ul><li>eprints in eprint archives typically exposed using OAI-PMH currently </li></ul><ul><li>repositories take different approaches to what they expose in their metadata </li></ul><ul><ul><li>work, or manifestations, or both </li></ul></ul>eprint (work) PDF manifestation PDF (manifestation) MS-Word (manifestation) now: expose separate simple objects (metadata only) future: expose complex objects (metadata and full text) eprint (work) PDF Word
  8. 8. Some observations… <ul><li>complex objects made up of component parts and metadata </li></ul><ul><ul><li>component parts need not be digital objects </li></ul></ul><ul><li>common approach to modelling objects crucial to interoperability </li></ul><ul><li>unfortunately… a common approach to modelling is difficult to achieve </li></ul><ul><ul><li>especially on an international scale </li></ul></ul><ul><li>but no ‘best practice’ yet for how to model the complex objects found in eprint archives and institutional repositories </li></ul>
  9. 9. MPEG-21 <ul><li>ISO standard that defines ‘ a normative open framework for multimedia delivery and consumption for use by all the players in the delivery and consumption chain ’ </li></ul><ul><li>MPEG-21 is modular (17 parts!) </li></ul><ul><ul><li>Part 2: DID – representation of digital objects </li></ul></ul><ul><ul><li>Part 3: DII – identification of digital objects </li></ul></ul><ul><ul><li>Part 4: IPMP – enforcement of rights expressions </li></ul></ul><ul><ul><li>Part 5: REL – declaration of rights expressions </li></ul></ul><ul><ul><li>Part 7: DIA – transcoding based on contextual information </li></ul></ul><ul><ul><li>Part 10: DIP – association of behaviors </li></ul></ul><ul><ul><li>Part 16: BF – binary representation of digital objects </li></ul></ul><ul><li>parts can be (and are) used autonomously </li></ul>
  10. 10. MPEG-21 DID <ul><li>ISO/IEC 21000-2: Digital Item Declaration </li></ul><ul><ul><li>second edition ISO standard </li></ul></ul><ul><li>representation of Digital Objects </li></ul><ul><ul><li>referred to as Digital Items </li></ul></ul><ul><li>3 sections </li></ul><ul><ul><li>abstract model – DID </li></ul></ul><ul><ul><li>representation of the Model in XML (DIDL) </li></ul></ul><ul><ul><li>W3C XML Schema </li></ul></ul><ul><li>other representation of DID may emerge </li></ul><ul><ul><li>ISO/IEC 21000-16: Binary Format </li></ul></ul><ul><ul><li>Resource Description Framework (RDF)? </li></ul></ul>
  11. 11. DIDL and digital libraries <ul><li>development of MPEG-21 largely driven by the big movie/video content owners and broadcast industries </li></ul><ul><li>little widespread involvement by digital library community </li></ul><ul><li>however, significant involvement of staff at LANL Research Library </li></ul><ul><ul><li>input into 2 nd edition of the standard </li></ul></ul><ul><ul><li>ISO to publish the standard for free on the ISO Web site </li></ul></ul>
  12. 12. MPEG-21 DID model container item (sub-)item component resource (datastream) instantiated as DIDL/XML document represents the digital item/object/asset items (with optional nested sub-items) made up of one or more components, each of which has one or more datastreams Descriptor/Statement Descriptor/Statement Descriptor/Statement Descriptor/Statement metadata and/or identifier
  13. 13. Example – journal article Item Descriptor/Statement dii:identifier doi:10.1234/5678 Component Descriptor/Statement dcterms:created 2005-02-22 Resource @mimeType application/xml @ref Component Descriptor/Statement dcterms:created 2005-02-21 Resource @mimeType @ref Item Descriptor/Statement dii:identifier doi:10.1234/5678 Component Descriptor/Statement dcterms:created 2005-02-2 Resource @mimeType application/xml @ref Component Descriptor/Statement dcterms:created 2005-02-21 Resource @mimeType application/pdf @ref <ul><li>consider a ‘journal article’ digital asset comprising a PDF document and an XML metadata record (both by reference) </li></ul><ul><li>the asset is mapped to a DIDL ‘Item’ element as follows… </li></ul>DIDL elements secondary info type value
  14. 14. MPEG-21 DIDL strengths <ul><li>MPEG-21 DID ‘abstract model’ provides a syntax-independent way of </li></ul><ul><ul><li>defining underlying ‘complex object’ model in use </li></ul></ul><ul><ul><li>mapping between complex objects from different repositories </li></ul></ul><ul><li>combination of DID and MPEG-21 Digital Item Identification (DII) allows for unambiguous global identification of complex objects and their component parts </li></ul>
  15. 15. MPEG-21 DIDL strengths (2) <ul><li>DID model (and associated DIDL XML schemas) provide open, extensible framework </li></ul><ul><li>in particular, the Descriptor/Statement mechanism provides a way of attaching arbitrary metadata (secondary information) to the digital object or any of its component parts </li></ul><ul><ul><li>checksums and/or signatures </li></ul></ul><ul><ul><li>DC description </li></ul></ul><ul><ul><li>rights metadata (MPEG-21 REL) </li></ul></ul><ul><ul><li>etc. </li></ul></ul>
  16. 16. Final thoughts… <ul><li>some danger that discussion about packaging formats is a religious issue (i.e. don’t bring it up in a job interview!) </li></ul><ul><li>the really difficult ‘issues’ are in the way that our complex objects are modelled </li></ul><ul><ul><li>applies to all the packaging formats, i.e the problem is independent of chosen packaging standard </li></ul></ul><ul><li>need widespread agreements about how we model our complex objects in order to achieve interoperability </li></ul><ul><li>need to do that on an international basis </li></ul>
  17. 17. Questions?
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