1. Norman Paskin International DOI Foundation
DOI System: overview
Norman Paskin
International DOI Foundation

2. Introduction
Overview: 5 minute animation
then:
More information on key points
Q and A

3. DOI = Digital Object Identifier (system) ®
Who?
DOI = Digital Object Identifier (system) ®
International DOI Foundation (“IDF”)
Common operations and governing organisation:
RAs = DOI Registration Agencies
members of IDF offering the DOI system
to customers who wish to assign DOIs
to offer a DOI-based service to users

4. Status
Foundation launched to develop system in 1998.
An ISO standard: ISO 26324
Currently used by c. 11,000 naming authorities (assigners)
e.g. 3,000 STM publishers, science data sets, entertainment industry, EU documents, etc.
87 million DOIs assigned to date
Via 9+ RAs (international)
DOI services provided by RAs: build on DOI system
Initial applications mainly are simple redirection to a URL.
More sophisticated functionality available e.g. multiple resolution

5. Scope
Digital Identifier of an Object
Object = any entity (thing: physical, digital, or abstract)
Resources, parties, licences, etc.
Initial focus was documents/media e.g. articles, data sets.
Now also moving into parties and licences.
Extending to other sectors
Digital Identifier = network actionable identifier (“click on it and do something”)
Extensible by design: not intended as a publishing-only solution (digital convergence)
Work with existing tools and data
International: RAs worldwide.

6. What it does Managed DOI Content Content DOI system DOI directory DOI
The DOI System
The DOI System
Overview
Overview
DOI
URL
What it does
Managed DOI
Content
DOI
system
DOI
directory
DOI
directory
Content 6

7. What it does
provides a resolvable, persistent, interoperable link:
resolvable – standard identifier syntax + network resolution mechanism (Handle System)
persistent – through:
technical infrastructure (registry database, proxy support, etc)
social infrastructure (obligations by Registration Agencies)
interoperable - through a data model (semantic interoperability)

8. International DOI Foundation Provides common infrastructure
The DOI System
The DOI System
Overview
Overview
Governance
International DOI Foundation
Provides common infrastructure
Technical: resolution, data model
Social: e.g. obligations for persistence, back-up, in event of failure, etc.
Deals with common issues
Standardisation, liaisons, etc.
Outreach to new communities
“Not for profit” membership federation
Registration Agencies are biggest part of membership
Elected Board, working groups, meetings
No full time staff (outsourced) 8

9. RAs and the DOI business model
The DOI System
The DOI System
Overview
Overview
RAs and the DOI business model
RAs are autonomous and independent of each other
RAs business model with their customers is decided by the RA
RAs obligation to IDF is a licence/operating agreement
All RAs share costs of common infrastructure (IDF)
All RAs implement standard DOI system
RAs can add their own services on top
RAs may choose to put DOIs “under the hood” or make explicit that this is “Driven by DOI”
Some RAs are commercial; most are themselves member communities (e.g. CrossRef, EIDR, DataCite) 9

10. Technical infrastructure
The DOI System
The DOI System
Overview
Overview
Technical infrastructure
Handle system: persistent identification in digital networks
Data model: principles for interoperability of data in e-commerce systems
Both used elsewhere: aim was to not re-invent the wheel
Handle:
Data Model: indecs. Linked Content Coalition 10

11. DOI uses Handle to resolve to data
The DOI System
The DOI System
Overview
Resolution
DOI uses Handle to resolve to data
Schematic of a DOI Handle record
DOI
Value(s)
Data type
Index
Data value
10.123/456
URL 1
Prefix
Suffix
URL 2
XML 3
<some XML>
HS_ADMIN
100
acme.admin/jsmith
XYZ 12
Each DOI has one or more Handle values (type:value)
Resolution can return all values, or all values of one type 11

12. DOI Handle technical infrastructure
Beijing (1)
Tokyo(1)
Taipei (1)
Denver (1)
Boston (1)
Reston (2)
Herndon (15)
Bologna (2)
Zurich (1)
Hanover (2)
Singapore – Amazon Cloud (9)
London - Rackspace Cloud (9)
DOI Handle Servers (46 servers in 12 locations)

13. Data model: high level People Content Deals
The DOI System
Overview
Data model: high level
High level model (from indecs)
People
make
Content
use
Deals
about do

14. Data model: in more detail
The DOI System
The DOI System
Data Model
Overview
Figure 1
Data model: in more detail
COA MetaModel
Overview
Descriptor
Descriptor
Role
Agent
Resource
Role
Role
Role
Name
Name
Verb
Verb
Identifier
Identifier
Every Relationship
has a Relator
Relator
Context
Annotation
Relator
Annotation
Category
Category
Flag
Role
Time
Place
Flag
Role
Role
Role
Quantity
Quantity
EntityTypes
AttributeTypes
EntityTypes
AttributeTypes
An Entity may have typed relationships
An Entity may have Attributes of any kind.
An Entity may have typed relationships
An Entity may have Attributes of any kind.
with Entities of any kind
(Attributes, which are a type of Resource,
with Entities of any kind
(Attributes, which are a type of Resource,
(including those of its own kind)
may have their own Attributes).
(including those of its own kind)
may have their own Attributes).
Contextual Relationships
Non Contextual Relationships
(illustrative: any Type of Entity may relate to any other)
Attributes (illustrative: any Entity or Attribute may have Attr
ibutes of any type) 14

15. Each DOI has some basic metadata
The DOI System
The DOI System
Overview
Overview
Data Model – end result
Each DOI has some basic metadata
All DOIs have this “kernel”
Metadata is held and managed by the RA
Common model for DOI System
More metadata can be added
Appropriate to an RA or DOI service
Some groups of DOIs will have the same metadata terms
Extensible to any level needed
Can use existing metadata and map it to DOI
DOIs with the same service or same metadata can be grouped and managed as a class 15

16. Social infrastructure
The DOI System
The DOI System
Overview
Overview
Social infrastructure
Shared development – e.g. APIs, etc
Shared tools e.g. running mirror servers
Obligations for persistence:
To customers (within the RA)
In event of failure, etc.(beyond the RA)
Collaborate
Enable shared DOI services where practical
A customer could use more than one DOI service 16

17. Through TC46/SC9 (“Information and Documentation”) – same as ISBN etc.
The DOI System
The DOI System
Overview
Overview
Standardisation
ISO 26324: 2012.
Through TC46/SC9 (“Information and Documentation”) – same as ISBN etc.
ISO standard contains basic specification
DOI Handbook and procedures has more detail of implementation
Other standards:
URI (DOI via http proxy)
URN 17

18. DOI and other identifier schemes
The DOI System
The DOI System
Overview
Overview
DOI and other identifier schemes
DOI has strong focus on interoperability and on working with existing and new schemes.
Can take an existing identifier and make it a DOI:
Use the existing identifier in a DOI suffix; or
Define “same as” identifier in the DOI metadata
Enables re-use of registries, metadata, etc.
Must be certain that the existing ID and the DOI refer to the same thing (easiest with an existing registry)
Complicated in digital content:
abstractions (e.g. current version or dated version; abstract work or specific edition; etc.)
Not always “same as”
Community and proprietary issues
See “Identifier Interoperability” fact sheet 18

19. DOI RAs and data DOI registration process DOI registration process
Kernel metadata
DOI registration process
Metadata for Service 1
Optional specific services
driven by DOI
Metadata for Service 2
Non-DOI Service
The RA manages:
the registration of the DOI
kernel metadata (same for all DOIs)
additional metadata (specific to a DOI application or “Service”)
May run multiple DOI application services
May run other (non-DOI) services

20. Interoperability between DOI RAs
DOI Registration
Kernel metadata
Additional metadata
for Service A
RA #1
DOI Registration
Kernel metadata
Additional metadata
for Service B
RA #2 X
To use a DOI in both service A and service B:
Registrant must register a DOI with both RAs; or
Better: RA and RA arrange to share information/services; or
Ideal: automated sharing of the DOI record across RAs
Technical interoperability can be helped by tools
Community interoperability (sharing and managing data) is the bigger problem

21. Choosing which RA to register with
DOI Registration
Kernel metadata
Additional metadata
for Service A
RA #1
DOI Registration
Kernel metadata
Additional metadata
for Service B
RA #2
DOI RAs are non-exclusive – anyone can use any RA to register a DOI
e.g. in China: ISTIC and CNKI both offer DOI Registration
BUT to use service A, choose to register your DOI with the RA that runs service A
Only that RA will have an interest in the specific set of metadata for that use
e.g. to use the audiovisual registry for film/broadcast = go to EIDR
Not all DOIs offer every service
Sometimes services (and so RAs) overlap:
Because a new specialised service comes onto the market (e.g. data citation)
Or because of competition (Service A and service B have the same aim)
Or because of fuzziness of categories
DOI RAs succeed because of the SERVICES they offer, not because they register DOIs

22. Quick summary: “Key facts on DOI system” factsheet
The DOI System
The DOI System
Overview
Overview
Documentation
Website:
Quick summary: “Key facts on DOI system” factsheet
Other Factsheets – more topics in detail:
DOI Handbook 22

23. DOI Update N PaskinThe DOI System
IDF Meeting June Overview
Norman Paskin