Digital Object Prototypes

1
Digital Object Prototypes
10th European Conference on Research and Advanced
Technology for Digital Libraries

• An Effective Realization of Digital Object Types

K. Saidis1, G. Pyrounakis2, M. Nikolaidou2, A.
Delis1
1Department of Informatics And Telecommunications
2Libraries Computer Center University of Athens
2
Outline

• The problem
• Develop an integrated web-based DL that manages
  diverse heterogeneous digital material in a
  unified manner
• Our proposed solution
• Digital Object Prototypes an effective
  realization of Digital Object (DO) types
• DOPs Overview
• Discussion

3
Pergamos Un. of Athens DL

• Over 1 million objects originating from 8
  disparate collections
• Heterogeneous, digitised material requiring
  detailed cataloguing
• Motivation
• Simplify speed up cataloguing
• Decrease development time
• Avoid custom coding for handling variations of
  digital material

4
Digital Objects

• Human generated artifacts comprised of 4
  components
• metadata, digital content, relationships
  behaviors
• Several ways to encode them METS, FOXML, RDF,
  MPEG-21
• Diverse kinds of material are represented using
  variations of DO components

5
The problem

• DOs (e.g. books, papers, photos etc) should be
  treated in a manner that reflects the nature of
  the underlying real-world objects
• DL systems do not capture, express or use the
  nature of DOs effectively DL users are forced to
  deal with each objects idiosyncrasies manually

6
Digital Object Prototypes

• Introduced in last years ECDL
• A Digital Object Prototype (DOP) is a DO Type
  specification, providing a detailed definition of
  a DOs constituent parts metadata, files,
  relationships and behaviors
• With the use of DOPs, high level services can
  handle DO component variations in a uniform manner

7
DOPs Contd.

• DOPs provide the means to generate user-defined
  types of digital objects
• DO type conformance DOs automatically conform to
  their respective DOP
• Inexpensive to add new types of digital material
  or modify existing ones (no custom coding
  required)

8
DOPs Contd.

• DOPs draw on the notions of the OO model to
  implement DO types
• All objects have a type
• Objects honor encapsulation
• Inheritance (under development)
• DOs are conceived as instances of their
  respective prototype
• Stored DOs are treated as serializations of DO
  instances

9
A DO Instance
10
Instantiation / Serialization
11
DOPs 3-tier DL Architecture
Composition of DO behaviors
DO Typing Instantiation
Storage
12
A DOP specifies

• Metadata element sets
• File types / conversions / batch ingestions
• Permitted relationships
• Private Public behaviors

13
Behaviors

• Encapsulation Private Public behaviors
• Private behaviors are executed by the DO instance
  behind the scenes (the object itself triggers
  selected functionality)
• Public behaviors are exposed to clients (clients
  trigger selected functionality)

14
Metadata Specification

• DOPs specify
• the metadata element sets used by all objects of
  this type
• the individual elements (fields) that constitute
  each set
• possible mappings among elements of these sets

15
Metadata Specification II

• Automatic loading / serialization of metadata
  sets
• Behavioral characteristics of metadata elements
• isMandatory, isHidden, isRepeatable,
  defaultValue, validation
• facilitate services to adjust to the objects
  requirements
• Mappings are automatically applied by the DO
  instance

16
Files Specification

• DOPs specify
• The permitted files and their allowed formats
• The information required to convert files from
  one format to another
• Batch file ingestion / automatic DO creation
  process for each file

17
Example

• Historical Archives Senate Session Proceedings gt
  Folders gt Sessions gt Pages
• What is a Page DO
• A digital image stored in various formats (e.g.
  high quality TIFF, web quality JPEG, thumbnail)
• What is a Session DO
• A complex DO, consisting of Page DOs and session
  proceedings metadata

18
Example Contd.

• Automatic file conversions
• Page DOs automatically generate the two derivate
  formats from the high quality image
• Batch Content Ingestion / DO Creation
• Session DOs generate Page DOs from zip files
  containing high quality images

19
Session DOP
20
Page DOP
21
Relationships

• DOPs specify
• The structural relationships the objects are
  allowed to participate in (e.g. child-of, or
  is-parent-of)
• Whether the objects are allowed to reference
  other entities, either internal (residing in the
  same DL) or external ones

22
DOPs and Collections

• DOPs live in the context of a collection
  (collection pertinent scope)
• Collections are represented in terms of
  special-purpose DOs
• Collections may contain other collections
  (hierarchical namespace)
• The Digital Library is the collection of all
  collections

23
Pergamos Collections DOPs
24
A hierarchy of DO instances
25
dl.histarch. DOPs
26
dl.folklore. DOPs
27
dl.papyri. DOPs
28
dl.theatre. DOPs
29
Summary

• We argue that digital objects do have types (they
  fall into categories with uniform characteristics
  and behavior)
• First realization of DO Type conformance DOs
  honor the specifications residing in their DOP
  automatically
• Effective management of diverse digital material
  the DL system interprets DO types, not the user

30
Future Work

• Implementation of DOPs inheritance (reuse new
  types can be derived from existing ones)
• Offline DOP validation process
• Make DOPs operate independently of the underlying
  repository
• Open source release of the DOPs framework

31
Thank you

• Questions?
• Email saiko_at_di.uoa.gr
• DOPs in action Pergamos demo tomorrow (Poster
  17)