Citation Linking for Electronic Journal Articles

1
Citation Linking for Electronic Journal Articles

• CNI Fall Task Force Meeting
• Phoenix AZ
• December 1999

2
What were going to talk about

• General model for reference linking (me)
• NISO / DLF / SSP / NFAIS workshops
• February 1999, Washington DC
• June 1999, Boston MA
• Appropriate copy problem (Dale)
• DLF Architecture Committee
• SFX

3
Why talk about it?

• Publicize the activity so far
• Seeking interested parties
• How can we move this effort forward?
• Who can/should participate?

4
What are we talking about?

• Reference (or citation) linking
• providing an actionable link from a reference to
  an object
• focus on electronic journal articles
• References
• from index databases (AI services, search
  services, citation databases)
• from article references section (bibliography)

5
What are we talking about (cont)

• Links
• maybe URL
• maybe some other link-key (identifier)
• Objects
• works / manifestations / items gt creations
• content vs. surrogates / substitutes

6
Puddles

• Closed systems where single agency controls both
  citations and content
• Publisher(s)
• Elseviers ScienceDirect, Wileys InterScience
• Aggregator service
• OCLC ECO
• Discipline
• NASA Astrophysics Data System, PubMed

7
Puddles (cont.)

• User Community
• OhioLink, University of Toronto
• Problems with Puddles
• ok when everything a user wants is inside the
  puddle
• not ok when content is limited, arbitrary, or
  incongruent with user needs

8
Open Reference Linking

• Any link to any object, regardless of which
  system the link,
• the object,
• or the user
  is in.
• Assume multiplicity
• Require interoperability

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WHAT WE ARE TRYING TO ACCOMPLISH
Any old system
Citation
Citation
LINK
CLICK
LINK
MAGIC
Cited Article
10
Model for open reference linking
Publisher
Reference Database
Location Database
Content
URL
Identifiers
Identifier
URLs
Citation
Client
Content
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Pieces of the problem

• Get a link for a reference
• Resolve the link to one or more locations of the
  target document
• Identify the most appropriate copy or copies of
  the target document for the user

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URL or Identifier

• Multiple locations
• Persistence
• Data management
• Nearly all implementations find identifier
  necessary
• Identifier name based

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How to get a link derived vs. dumb

• Derived Construct it from data in the reference
  
• shared within a discipline (ADS)
• national standard (SICI)
• cope with multiplicity (S-Link-S)
• Dumb Look it up from data in the reference
• e.g. DOI-X

14
How to get a link static vs. dynamic

• Static Pre-constructed
• embedded in the source document
• stored in a table associated with the source
• Advantage opportunity to review and correct
• Dynamic Supplied on-the-fly
• looked up or calculated when citation or
  reference displayed
• Advantage currency and flexibility

15
Static and Dynamic Linking
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Model how to get a link
Publisher
Reference Database
Identifier(s)
citation
Client
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Resolve the link to location(s)

• For given identifier
• look up in database mapping identifier to
  location(s)
• return list of locations where items may be found
• return additional information to distinguish
  between items (e.g. format)

18
Model how to resolve a link
Publisher
Location Database
Identifier
URL(s)
Client
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How to resolve the link

• In puddles
• may be single type of link
• may be handled by system software
• In open reference linking
• will be multiple types of links
• need to find appropriate resolution service(s)
• need protocol for communicating with resolution
  service

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How to find appropriate resolver

• Currently
• Browser plug-in
• Proxy server
• Tunnel identifier in URL
• Future ?
• URN model of distributed resolution
• web browser support for user configuration of a
  hierarchy of identifier resolution services

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WHAT IF MORE THAN 1 COPY EXISTS?

• Elsevier journals, for example, are available
  from
• Elsevier ScienceDirect
• University of Michigan PEAK
• OhioLink
• University of Toronto
• Florida Center for Library Automation

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WHICH URL?
Name Resolver
NAME
URL?
Sciencedirect.com?
Ohiolink.edu?
Utoronto.ca?
Umich.edu?
FCLA.edu?
IT SOMETIMES DEPENDS ON WHO THE USER IS...
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SOURCES OF MULTIPLE COPIES

• Aggregators
• OCLC, EBSCO, Bell Howell, Lexis/Nexis, IAC
• Local loading
• OhioLink, University of Toronto, University of
  Florida
• E-print
• xxx (LANL), Cogprints, RePec.

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WHY MULTIPLE COPIES

• Performance -- may want highly used objects
  closer to the user in network terms
• Different players can provide different service
  models using same content
• e. g., gathering topically related materials
  into knowledge bases (Ovid)
• published and unpublished articles in a single
  e-print service

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WHY MULTIPLE COPIES (continued)

• Competition in repository services
• Encourages functional innovation
• Rationalizes prices for services
• Archiving
• Institutional failure is as great a danger as
  technological failure, particularly when dealing
  with commercial players

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CURRENT STATE

• Few working solutions (Linkout _at_ NIH, SFX
  prototype _at_ UGhent and LANL)
• DLF/CNRI discussion of the following 3 models
• All intervene in the name resolution process to
  select the appropriate URL to return

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Local Name Resolver
1 Name Resolution Request
2. Address (if found locally)
OR
2. Name Resolution Request (if address not found
locally)
3. Address
Universal Name Resolver
LOCAL CACHE
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Universal Name Resolver
Filter Server
2. Name Resolution Request
1. Name Resolution Request
3. Addresses (URL1, URL2, URL3.)
6. Address
4. Request Bibliographic Data (if
appropriate source is ambiguous))
5. Bibliographic Data
Reference Server
PROFILE-BASED FILTER
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Universal Name Resolver
Filter Server
2. Name Resolution Request
1. Name Resolution Request
8. Address
3. Addresses (URL1, URL2, URL3.)
4. Availability Query
6. Availability
4. Availability Query
7. Availability
4. Availability Query
5. Availability
Content Service 1
Content Service 2
Content Service 3
BROADCAST-RESULT- BASED FILTER
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SOME ISSUES

• Ugly, ugly, ugly
• In part because linking is to articles, most
  access based on serial title and year
• All solutions require a lot of coordination
• Users who are members of multiple rights
  communities are a major complication

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1. Service cookie-pusher URL
Portal
7. Page of links
6. Request for links
3. Cookie redirect to service
2. Cookie info
SFX Server
5. Article or citation SFX links based on
cookie
EXTERNAL SFX AWARE SERVICE
4. Service request cookie
Service
Cookie Pusher
SFX LINKING SYSTEM
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SFX vs Name Based Linking

• SFX
• generalized for many kinds of links (including to
  paper copies)
• requires explicit cooperation of citation source
• SFX does not simplify providing appropriate link
• but can work with both algorithmic and name-based
  links
• and methodology provides bibliographic context
  for link derivation

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So

• Different approaches have different strengths
• mix and match possible
• The big issue who has the motivation to address
  this seriously?
• Interested? Contact us!

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The requisite URLs
Report on NISO/DLF/SSP/NFAIS meetings
http//www.dlib.org/dlib/july99/caplan/07caplan.ht
ml
Paper on DLF/CNRI appropriate copy discussion
http//www.niso.org/DLFarch.html
and contact information
pcaplan_at_nersp.nerdc.ufl.edu
dale_flecker_at_harvard.edu