OCLC Users Council Briefing on Persistent Identifiers

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OCLC Users CouncilBriefing on Persistent
Identifiers

• Stuart Weibel
• OCLC Office of Research
• May 24, 2004

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Identity

• A globally ID for
• Every concept (term)
• Every resource
• Every objet dart
• Every agent
• Every cow,
  pair of socks,
  and razor blade (RFID)

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For the Information World

• We care about identifying resources
• Physical
• Virtual
• Conceptual
• Knowing you have what you think you have
• Knowing youre talking about the same things

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What do we want from Identifiers

• Reliability
• Resolvability
• Persistence throughout the life cycle of the
  information object
• What are the business models to support this?

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Current efforts at OCLC involving persistent
Identifiers

• PURLs
• Open URLs
• info URIs
• ERRoLs
• Registration of terminology

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• PURL Persistent Uniform Resource Locators
• PURLs look like URLs they ARE URLs
• PURLs emerged from OCLCs participation in the
  IETF URN activity
• A tool for managing names and namespaces since
  1996

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The 404 Problem

• Resources disappear
• Some are actually gone
• Disk reorganizations take place
• Changes in responsibility for resources occur
• URLs serve double duty as names and locators
• Making URLs symbolic names will improve their
  usefulness

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What is a PURL?

• PURL Persistent Uniform Resource Locators
• They look like URLs they ARE URLs
• No new technology, no new protocols
• A tool for managing names and namespaces

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How PURLs Work

• PURLs take advantage of inherent redirection
  facility in the HTTP protocol
• PURLs provide an additional level of indirection
  that maps a symbolic identifier to a network
  location
• PURLs work without plug-ins or other special code
  in browsers they are just URLs
• No New Technology added!

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What does Persistentmean?

• Not a guarantee of perpetual access
• Not a magic solution to the 404 problem
• Not persistence of resources, but rather of the
  names
• PURLs are a tool that can be used to manage
  resource names and locations with greater
  reliability

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Persistence derives from

• The social or contractual commitments of
  organizations responsible for managing
  information resources.
• Technology can help, but the problem is, at its
  heart, a social one.

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PURL Server as a Redirection Server
http GET
Client
http redirect
http GET
Resource Server

resource
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PURL Server as a Resource Server
http GET
Client
PURL Server
resource
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Do I have to run my own PURL Server?

• OCLCs PURL Server is open to all, including the
  ability to request domains
• As of Monday, May 24, 2004
• PURLs Created 571 427
• PURLs Resolved 86 010 679
• Unique Client Systems 5 763 071
• The PURL server software is available at the
  purl.org site for anyone to download and use
  without cost or restriction.

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How are PURLS different from DOIs?

• DOIs are a closely related identifier system
  based on Handles
• DOIs are a technology with a business model
  wrapped around them
• DOIs cost money
• The Commitment is the key

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In Summary

• PURLs offer a methodology and tool set for
  managing resource names and namespaces
• Neither PURLs nor any other technology are a
  replacement for policies or commitments to manage
  resource names
• PURLs represent a community-based solution
  founded in freely available, widely deployed
  technology.
• http//purl.org

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Identifiers for Concepts

• How do you use terminology in the Web World?
• The Semantic Web is about semantics exchanging
  tokens of meaning between machines
• Identifiers are a fundamental part of this.

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Concepts can be expressed in language independent
ways (even if imperfectly)

• Vietnamese War, 1961-1975 (English language
  version of DDC 22) DDC/22/eng//959.7043
•  
• American War, 1961-1975 (Vietnamese
  language version of DDC 22,)
  DDC/22/vie//959.7043

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Boundary-Free Community Terminologies

• Controlled Vocabularies have been with us for a
  long time
• Hypothesis there are specific functional
  requirements that terminologies should embody in
  order to be useful in the realization of the
  Semantic Web

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Terminology Identifiers

• Global, persistent identifiers that reflect the
  functional characteristics of webulated
  controlled vocabularies can help us remove
  boundaries between and among communities and
  disciplines.
• Problem Identify these functional requirements
  and tailor identifier systems to meet them.

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INFO URIs

• An effort to provide a missing part of the naming
  architecture of the Web
• Separate resolution from identity
• Basis for the naming architecture of Open URLs
• Possibly useful in many other areas (terminology
  identifiers)

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INFO URIs(continued)

• Substantial controversy about separating identity
  and resolution
• IETF pushback is substantial
• Experimental use will determine future

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ERRoLs

• Extensible Repository Resource Locators
• Constructed, Dynamic URLs that resolve to
  metadata and content stored in a community of
  OAI Repositories
• A Service-based identifier
• See the Research Works pages for further
  information

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DCMI Working Groupon Persistent Identifiers

• Chartered to provide guidance about the use of
  persistent identifiers in DC Metadata
• Meeting in Feb of 2004
• Meeting at Persistent Identifier Symposium in
  Cork, Ireland, in June
• Survey and summarize use, provide guidance about
  declaration and use.

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Identity is more important than ever

• Information Resources
• People
• Terms
• Concepts
• Even cows
• In the end, it is about the reliability and trust
  assets of the organizations that manage them