DOI SYSTEM: OVERVIEW

International DOI Foundation

• Origins of the DOI System• Current position of DOI System activities• Persistence• Actionable identification • Interoperability • System components • Standardisation • DOI System applications

Outline / Key concepts doi>

DIGITAL OBJECT IDENTIFIER (DOI®) SYSTEM

Article in: Encyclopedia of Library and Information Sciences (forthcoming) third edition (Taylor & Francis)

http://www.doi.org/overview/070710-Overview.pdf

Further reading doi>

The DOI System

• DOI (Digital Object Identifier) System: www.doi.org

• Initially developed from the publishing industry but now wider • a non-profit collaboration to develop infrastructure for persistent

identification and management of content• Approx 2000 user organisations (through agencies)• CrossRef (scholarly publishers); EC; science data; major ISBN agencies;

etc.

• Currently being standardised in ISO (TC46/SC9)• the home of ISBN etc “content identifiers”

• One application of the Handle System®

• adds to it additional features – social and technical infrastructure, policies, metadata management

• focus on one area of interest (content/intellectual property) • offers a specific data model based on indecs (discussed later)• DOI System technology equally applicable for parties and licences

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• “In 1965 the largest British book wholesaler WH Smith announced their intention to move their wholesaling and stock distribution operation to a purpose built warehouse in Swindon [in 1967]. To aid efficiency they would install a computer, and this would necessitate the giving of numbers to all books held in stock…”

• “The idea of numbering books is not new. One British publishing house has been giving numbers to its books for nearly a hundred years. What is an entirely new concept, however, is that numbers should be given to all books; that these numbers should be unique and non-changeable; and that they should be allocated according to a standard system…”

(David Whitaker, The Bookseller, May 27 1967)

1966: ISBN began “identification numbering” doi>

ISO continues “identification numbering”

ISO 2108 International Standard Book Numbering (ISBN)

ISO 3297 International Standard Serial Number (ISSN)

ISO 3901 International Standard Recording Code (ISRC)

ISO 10444 International Standard Technical Report Number (ISRN)

ISO 10957 International Standard Music Number (ISMN)

ISO 15706 International Standard Audiovisual Number (ISAN)

ISO 15707 International Standard Musical Work Code (ISWC)

ISO Project 20925 Version identifier for Audiovisual Works (V-ISAN)

ISO Project 21047 International Standard Text Code (ISTC)

ISO Project 27729 International Standard Name Identifier

ISO Project 26324 Digital Object Identifier System

http://www.collectionscanada.ca/iso/tc46sc9/Information and Documentation - Identification and Description

1. trend towards identifiers of abstract entities2. all ISO TC46SC9 identifiers now carry mandatory structured metadata

to specify the item identified (either from start, or when revised)

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Web-related identifiers

• URI, URL and URN• Not sophisticated enough alone for content management • Additional techniques: PURLs, RDF, SW, ARK, N2T, Handle, etc

• Related standards: • Open URL

• A syntax to create web-transportable packages of metadata and/or identifiers about an information object

• Not an identifier, but a complementary technology for appropriate redirection of identifier resolution

• in use with URLs, Digital Object Identifiers (DOI names)• "info" URI Registry

• Turn legacy identifiers (e.g. info:lccn/2002022641) into URLs • IETF RFC 4452: The "info" URI Scheme for Information Assets with

Identifiers in Public Namespaces. http://info-uri.info/

Note: DOI System is not designed ONLY for the web, but it is the current most common digital environment.

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“Identifier” as numbering schemes – Registries– Normally central control, commitment– Examples: ISBN, EAN bar codes, IANA, ITU phone numbering plans etc – Normally focus on attributes (metadata)

“Identifier” as syntax specifications – Normally little central control – e.g URI (URL); MPEG-21 DII – Few structured attributes, low barriers to entry– Some more structured than others: e.g. URN, info URI

Other confusions:– Some practical systems use both schemes and specifications– Representations and interactions between different schemes and

specifications:• e.g. an ISBN can be expressed as a URL, as an EAN bar code, a DOI name, etc

– Identifier as “system” versus as a “unique label” – Schemes begin to be used for things outside scope

Terminology: the over-used term “identifier” doi>

• Information Identification - a report to STM publishers (Mar 95)• Uniform File Identifiers - a report to AAP publishers (Oct 95)• “..need to unify in one scheme music, audiovisual, document management, internet engineering, digital libraries, copyright registration and object based software” [i.e. web was not

the focus]• “..maximise utility of digital objects; enable core interoperability; enable integration of disparate sourced data; ability to trace ownership to manage rights”• requirements:

– protect legacy investments– enable interoperability– provide link between digital and physical– maintain privacy of users– have persistence– standard syntax– global scalability– global uniqueness– global meaning

• Led to launch of DOI System initiative (AAP committee, Uniform File Identifier)

1995: Armati Report doi>

ActivitytrackingActivitytracking

Full implementation

Full implementation

Initial implementation

Initial implementation

Single redirection (persistent identifier)

Metadata Other efforts, standards, etc

Multiple resolution

A continuing development activity

(1) DOI System: development in three tracks doi>

(2) Creation of an organisation

International DOI

Foundation

members &

Key driver: cost reduction Key driver: spend on development

Operating Federation

Agencies

Clients

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Current DOI System activity (Oct 2007) doi>

Registration Agency Prefixes DOI name registrations Jun-Oct 2007

DOI name registrations to date

CrossRef 945 2,135,117 29,517,872

Bowker 74 3,031 745,873

TIB 11 41,583 540,601

CNRI/default (experimental)

66 190 143,477

mEDRA 410 14,111 126,895

Nielsen BookData 211 9 36,578

CAL 270 16 451

OPOCE 300 33 57

Wanfang Data* 2 0 0

TOTAL 2027 2,592,775 28,419,009

Source: http://dx.doi.org/10.1000/127 (restricted access)

• Focus on enabling current RAs to generate more DOI names• New RAs in new areas • Social infrastructure development (RA policies) • Business model:

doi>Current strategy

IDF

RA

C

Incentive scheme: large discounts per DOI name for large numbers of registrations,

e.g. 25% -> 90%+

IDF has no role in this

• “It is intended that the lifetime of a [persistent identifier] be permanent. That is, the [persistent identifier] will be globally unique forever, and may well be used as a reference to a resource well beyond the lifetime of the resource it identifies or of any naming authority involved in the assignment of its name.”

• [Persistent Identifier] = URN in IETF RFC 1737: Functional Requirements for Uniform Resource Names. (http://www.ietf.org/rfc/rfc1737.txt)

• Persistence is more a matter of social issues than technical solutions• Technology can assist.

Persistence doi>

Persistent identifier applications

ISSUES• What are we identifying with this identifier? [content not just bits]• What are we resolving to from this identifier? • What, if any, explicit metadata are we making available?• How will the cost of providing the infrastructure be met?

THEMES• Identification of entities of all forms

– To be used in variety of contexts • Appropriate use of metadata at appropriate level

– Development of ontology tools to describe entity relationships• Persistent Interoperable Precise Automation Logic

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• DOI name = Digital Object Identifier Name • An implemented identifier system• Packaged system of components• Principles of persistent identification including semantically

consistent interoperation

• Implemented identifier systems – actionable labels following a specification – e.g. Bar code system, DOI System – “if you use this system, then the label IS actionable”– Packaged system offering label + tools + business model– A packaged system is not essential, but is convenient

Persistent identifier applications

Data Model Resolution

Syntax Policies

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DOI name syntax can include any

existing identifier, formal or informal,

of any entity

• An identifier “container” e.g.– 10.1234/5678– 10.5678/978-0-7645-4889-4– 10.2224/2007-01-0verview-DOI

• NISO standard Z39.84• First class object: name

– Not “intelligent” as a label – Cannot tell what it is from looking at the

DOI name• Redirection through resolution

Data Model Resolution

Syntax Policies

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DOIdirectory

URLURL

URL

URL

URL

URL

URL

URL

URL

URL

URL

URL

URL

URL

Content

Content

Assigner

DOIdirectoryDOI

directory

DOIDOI

DOI

DOI

DOI

DOI

DOIDOI

DOI

DOI

DOI

DOI

DOI

DOI

Resolution allows a DOI name to link to

any & multiple piecesof current data

• Resolve from DOI name to data– initially Location (URL) – persistence

• May be to multiple data:– Multiple locations– Metadata– Services– Extensible

• Uses the Handle System- Implementing URI/URN concept- Advantages of granularity, scalability,

administrative delegation, security, etc

Data Model Resolution

Syntax Policies

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Why do we need “metadata”?

• Having an identifier alone doesn’t help – we want to know “what is this thing that’s identified?”

– we want to know precisely – precisely enough for automation

• There’s lots of metadata already: which should be (re-) used• People use different schemes: need to map from one scheme to

another (e.g. does “owner” in scheme A mean “owner” in scheme B?)

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DOI System data model

• The underlying model of how data within the DOI System relates to other data

• Two components– Data Dictionary + DOI Application Profile Framework

• Data Dictionary– Provides tool for precise description of entity through metadata (and

mapping to other schemes).

• DOI Application Profile framework. – Provides means of relating entities: grouping entities and expressing

relationships– A mechanism for grouping DOI names with similar properties

• DOIs, APs, and DOI System services built using these:– have many-to-many relationships: expressed through multiple

resolution (handle) – may have precise descriptions: expressed through metadata in Data

Dictionary

doi>

784369

965876

456

908

453

Application Profile

Application Profile

The properties of groups of DOI names are defined as APs

Service Instance

Service Instance

Service Instance

APs have one or moreServices

Application Profile (AP) Framework

965

876

456

453

784

369

908

Entities are identified by DOI names

Service Definition

Service Definition

Services havedefinitions

Service Definition

doi>

965

784369

965876

456

908

453

Service Instance Service Definition876

456

453

784

369

908Service Instance

Application Profile

Application Profile

453784

Application Profile

Service DefinitionService Instance

Service Instance

Service Definition

The properties of groups of DOI names are defined as APs

APs have one or moreServices

Services havedefinitions

Application Profile (AP) Framework

• New APs and services may be created or made available• One change to an AP to affect all DOI names within that AP

Entities are identified by DOI names

Service Definition

doi>

<indecs> Data Dictionary

+DOI AP framework

• Metadata tools: – a data dictionary to define– a grouping mechanism to relate

• Necessary for interoperability – “Enabling information that originates in

one context to be used in another in ways that are as highly automated as possible”.

• Able to use existing metadata – Mapped using standard dictionary– can describe any entity at any level of

granularity

Data Model Resolution

Syntax Policies

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DOI Systempolicies

allow any business model

for practical implementations

• Implementation through IDF– Governance and agreed scope, policy, “rules of the road” ,

central tools (dictionary, resolution mechanism)– Cost-recovery (self-sustaining)

• Registration agencies (“franchise”)– Each can develop own applications– Use in “own brand” ways appropriate for their community– Examples: CrossRef, OPOCE

Data Model Resolution

Syntax Policies

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Costs

• For an everyday user: • Free: any DOI name may be resolved by anyone• No obligations

• For an assigner:• Must work through a Registration Agency • Cost depends on application: DOI registration is bundled in

• e.g. CrossRef – crosslinking of citations: for a publisher, from $275 per year (2008)

• For a Registration Agency:• Must be a full RA member of the International DOI Foundation

• Fees based on volume • Developing, managing, implementing, standardising, etc:

• Paid for by International DOI Foundation (open to anyone)

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Resolve

Handle resolution technology allows you to access any kind of Service associated with your DOI name.e.g.

These services depend on metadata

Identify

DOI name syntax can include any existing identifier, formal or informal, of any entityeg10.2341/0-7645-4889-110.5678/978-0-7645-4889-410.1000/ISBN 076454889110.1234/OPOCE_presentation10.2224/2007-1-29-CENDI-DOI

Describe

DOI name metadata can be of any type, standard or proprietaryeg OnixForBooksOnixForSerialsIEEE/LOMMARCDublin CoreProprietary scheme

(but if you want to interoperate with anyone else in the DOI System network, you map to the <indecs> Data Dictionary (iDD).

More than an identifier…

A package of services is defined for an Application

Profile

Standardisation of DOI System (ISO TC46/SC9)

• DOI System as ISO TC46 standard: entire DOI System• Refer to component tools (Handle System, Data Dictionary,

etc) as informative references • Aim to separate existing “DOI Handbook” into formal standard

(ISO) and operating manual (IDF)• Show that DOI System supports (does not compete with) other

TC46/SC9 “identifiers”: offers option of adding Internet actionability, interoperability, in a standard way

• Draft now finalised • Supporting materials (response to comments, FAQ) available• 2008 standard?• Recent overview article is based on ISO draft:

– http://www.doi.org/overview/070710-Overview.pdf

• DOI Handbook to be revised

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• The main use of the DOI System is not simply to register an identifier

• It is to make use of the identifier in a SERVICE offered to users• E.g. CrossRef provides bibliographic citation pre-and post-

production look-up service across hundreds of publishers • It uses DOI names as one part of its service• It has become a de-facto requirement for academic publishing

doi>DOI System applications

• Multiple services may exist for an identifier – Don’t assume only monopoly services– One service may be definitive; some may be better than others

• Multiple identifiers – Need to distinguish abstractions, representations, compound

objects– Relation of DOI names to other identifiers (Bookland DOIs etc)

• Interoperability becomes more important as an economic feature when there are multiple services or multiple uses – which there will be eventually– Don’t design only for today

• Common frameworks for naming and meaning (to do all this) become important when services cut across silos; across media; from different sources; etc – Indecs–based approach (like ONIX etc)

• Multiple resolution: returns multiple results in response to a request (e.g. a choice, an automated service) – need some way of grouping and ordering those results, e.g.

Handle value typing

Application issues doi>

• General case• ISO standardisation of DOI System

– “A DOI name is not intended as a replacement for other identifier schemes, but when used with them may enhance the identification functionality provided by those systems with additional functionality…”

• Incorporate the other identifier into the DOI name syntaxand/or

• Record the other identifier in the DOI name metadata.

• Each scheme retains its autonomy but works together • ISBN and ISSN have already agreed options

doi>DOI names work with existing identifier schemes

• What does this DOI identify (precisely)?– For interoperable uses: use in services outside the control of

the assigner

• Metadata scheme already worked out– Kernel plus Application Profiles (extensions)

• Standard ways of declaring simple metadata – e.g. for Open URL uses – Interoperability is key aspect which will tip requirements

doi>DOIs can be used to define and declare

• Suppose I have here a pdf version of Defoe’s “Robinson Crusoe” issued by Norton. I find an identifier – is it of:– All works by Daniel Defoe – The work “Robinson Crusoe”?– The Norton edition of “Robinson Crusoe”? – The pdf version of the Norton edition of…. ?– The pdf version of…held on this server…?

• Most digital objects of interest have compound form, simultaneously embodying several referents.– Multiple identifiers may be necessary (like music CDs)

• Identifiers assigned in one context may be encountered, and may be re-used, in another place or time - without consulting the assigner. You can’t assume that your assumptions made on assignment will be known to someone else.

doi>DOI names to define the entity

• DOI name of one item may be related to DOI name of another • Through multiple resolution, metadata, Application Profiles…

• Example: A DOI name of a work could resolve to several available formats, languages, etc.

doi>DOI names to express relationships

ArticleDOI name

12345

Chinese version DOI name

56789

• Examples:

• Scientific data – TIB (Registration Agency) is an example

• Biological nomenclature – disambiguation and extension of the current taxonomy

models: Names-4-Life: (IDF member)

• Clinical Trials– identifying specific trials and sub-sets of items– UK project currently using DOI names on pilot basis

doi>DOI names for “non-traditional” entities

• Example:• Book fragments – tables, figures, chapters, exercises• Interactive e-books• Some may use other identifiers which could become DOI names;• Some may be in scope but not yet widely used (e.g. ISBNs for

Chapters);• Other may require new DOI names• Book Industry Study Group (BISG) working on this

• Others:• Nature “precedings”; Scirus “topic pages”; some blogs?

doi>DOI names for “new” traditional entities

Significant benefit of Handle System:• Resolve from one DOI name to several different results • One-to-many linkage • Resolution request would give:

– all results, or – all results of one type

• Need a framework to build these applications on: group similar uses so that the results are predictable and can be used across applications

• DOI Application Profile framework• Handle System “data value typing”

• CrossRef to use for e.g. location-dependent resolution • Other business cases?• Could express relationships (ISTC to ISBNs etc)

doi>DOI name multiple resolution

URL 2 http://a-books.com/….

DLS 9 acme/repository

HS_ADMIN 100 acme.admin/jsmith

XYZ 100111001111012

Handle dataHandle Data type Index

10.123/456 URL 1 http://acme.com/….

Handles resolve to typed data

Rules for data type construction: www.handle.net/overviews/types.html

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• Resolve DOI name with some additional information to give results depending on context

• Open URL: see e.g. http://www.crossref.org/03libraries/16openurl.html– Resolve to same content at different location (by user)

• Full contextual resolution: Handle System can do this (DVIA)– Resolve to different content (by user)– Of interest re licensing etc but not yet part of DOI System

• Steps in evolution: – URLs: not useful for long term management – naming and resolution: “get me the right thing”– contextual resolution: “get me the thing that is right for me”

(e.g. “that I have access rights for”)

doi>DOI name contextual resolution

Several DOI Name Tools have been developed, from a variety of sources

http://www.doi.org/tools.html• Such as plug-ins,

e.g. Adobe Acrobat plug-in • At different stages of development or use

doi>DOI name tools

DOI SYSTEM: OVERVIEW

International DOI Foundation