UKOLN is supported by: Content packaging and MPEG-21 DID Andy Powell, UKOLN, University of Bath JISC Joint Programmes Meeting, July 2005, Cambridge a centre of expertise in digital information management

JISC Joint Programmes Meeting2 Contents why how 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.

JISC Joint Programmes Meeting3 Why… … do we need packaging standards? because nothing in life is simple! applications tend to be built around aggregate objects of one kind or another –digitised books (multiple parts, i.e. pages) –learning objects (pathway thru multiple objects) even objects that look simple (e.g. an eprint in an eprint archive) turn out to be complex we need to exchange ‘complex objects’

JISC Joint Programmes Meeting4 Packaging standards framework for encoding ‘complex objects’ –containing multiple objects and/or metadata –may be nested often using XML as the encoding framework component objects embedded ‘by value’ –XML fragments or Base64 encoding or … or passed ‘by reference’ –URI like all standards, there are plenty to choose from: –METS, IMS-CP, MPEG-21 DID, XFDU (CCSDS) XFDU = XML Formatted Data Unit CCSDS = Consultative Committee for Space Data Systems XFDU = XML Formatted Data Unit CCSDS = Consultative Committee for Space Data Systems

JISC Joint Programmes Meeting5 Example 1 – digitised book consider digitised book in a ‘digital library’ complex object (book) made up of component parts (pages) the object and the parts each have one or more chunks of associated metadata parts may be embedded (by value) or linked (by reference) typical application: ‘virtual page turner’ typical packaging format: METS page book

JISC Joint Programmes Meeting6 Example 2 – learning object consider a learning object (whatever that is!) complex object made up of one or more parts (other learning objects) –documents, images, videos, interactive objects, audio files, maps, etc. –each with IEEE LOM metadata –some notion of workflow or sequencing ‘thru’ the parts typical application: VLE typical packaging format: IMS-CP PDF document learning object video multiple- choice test

JISC Joint Programmes Meeting7 Example 3 - eprint eprint (work) PDF manifestation PDF (manifestation) MS-Word (manifestation) now: expose separate simple objects (metadata only) future: expose complex objects (metadata and full text) eprints in eprint archives typically exposed using OAI-PMH currently repositories take different approaches to what they expose in their metadata –work, or manifestations, or both eprint (work) PDFWord

JISC Joint Programmes Meeting8 Some observations… complex objects made up of component parts and metadata –component parts need not be digital objects common approach to modelling objects crucial to interoperability unfortunately… a common approach to modelling is difficult to achieve –especially on an international scale but no ‘best practice’ yet for how to model the complex objects found in eprint archives and institutional repositories

JISC Joint Programmes Meeting9 MPEG-21 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’ MPEG-21 is modular (17 parts!) –Part 2: DID – representation of digital objects –Part 3: DII – identification of digital objects –Part 4: IPMP – enforcement of rights expressions –Part 5: REL – declaration of rights expressions –Part 7: DIA – transcoding based on contextual information –Part 10: DIP – association of behaviors –Part 16: BF – binary representation of digital objects parts can be (and are) used autonomously

JISC Joint Programmes Meeting10 MPEG-21 DID ISO/IEC : Digital Item Declaration –second edition ISO standard representation of Digital Objects –referred to as Digital Items 3 sections –abstract model – DID –representation of the Model in XML (DIDL) –W3C XML Schema other representation of DID may emerge –ISO/IEC : Binary Format –Resource Description Framework (RDF)?

JISC Joint Programmes Meeting11 DIDL and digital libraries development of MPEG-21 largely driven by the big movie/video content owners and broadcast industries little widespread involvement by digital library community however, significant involvement of staff at LANL Research Library –input into 2 nd edition of the standard –ISO to publish the standard for free on the ISO Web site

JISC Joint Programmes Meeting12 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 metadata and/or identifier

JISC Joint Programmes Meeting13 Item Descriptor/Statementdii:identifier doi: /5678 Component Descriptor/Statementdcterms:created Component Descriptor/Statementdcterms:created Item Descriptor/Statementdii:identifier doi: /5678 Component Descriptor/Statementdcterms:created Component Descriptor/Statementdcterms:created Example – journal article consider a ‘journal article’ digital asset comprising a PDF document and an XML metadata record (both by reference) the asset is mapped to a DIDL ‘Item’ element as follows… DIDL elements secondary info type value

JISC Joint Programmes Meeting14 MPEG-21 DIDL strengths MPEG-21 DID ‘abstract model’ provides a syntax-independent way of –defining underlying ‘complex object’ model in use –mapping between complex objects from different repositories combination of DID and MPEG-21 Digital Item Identification (DII) allows for unambiguous global identification of complex objects and their component parts

JISC Joint Programmes Meeting15 MPEG-21 DIDL strengths (2) DID model (and associated DIDL XML schemas) provide open, extensible framework 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 –checksums and/or signatures –DC description –rights metadata (MPEG-21 REL) –etc.

JISC Joint Programmes Meeting16 Final thoughts… some danger that discussion about packaging formats is a religious issue (i.e. don’t bring it up in a job interview!) the really difficult ‘issues’ are in the way that our complex objects are modelled –applies to all the packaging formats, i.e the problem is independent of chosen packaging standard need widespread agreements about how we model our complex objects in order to achieve interoperability need to do that on an international basis

JISC Joint Programmes Meeting17 Questions?