1. Technology Blitz:
Making Sense of the
Technology Landscape
for Publishers
The State of Linking
and Searching
Chuck Koscher
Director Of Technology
SSP
Technology Blitz 1

2. In the beginning …
Tim Berners-Lee conceived the WWW to provide
universal access to documents on the network
• Uniquely identify everything
• A way to access them (Hyper Links)
To do this he invented 3 things …
1. A simple protocol to communicate over (HTTP)
2. A common document language (HTML)
3. An identification scheme (UniversalResource Identifier ––URI)
(Uniform ResourceLocator – URL)
Identifier URI)
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3. URLs are Unreliable
 Links to a location are fragile

Documents move around the Web and change over time (versions)

Available in multiple formats and multiple places (appropriate copy)
 Spinellis, “The Decay and Failures of Web References”. Communications of
the ACM. 46(1), 71-77, 2003
 Examined 4300 URL citations in articles from ACM and IEEE
 After 4 years 40-50% of referenced URLs become inaccessible
 Larwrence et al. “Persistence of Web References in Scientific Research”.
IEEE Computer, 34(2), 26-31, 2001
 Examined 67,000 URL citations from 270,000 articles
 23% from 1999 and 54% from 1994 were invalid
 Brooks, “Broken Links: Just How Rapidly Do Science Education Hyperlinks
Go Extinct?”. University of Nebraska, 2003
 Loss after 35 months:
‘.edu’: 40% ‘.com’ : 53% ‘.org’ : 25%
Technology link to an identifier not to a location
SSP Blitzto an identifier not to a location
link 3

4. Why link in the first place
 ‘Publish or perish’ corollary: ‘if it is not on-line it doesn’t exist

If it is on-line but not linked to no one will find it

If it is on-line but does not link out it is not as valuable
 Linked references are expected

An actionable bibliography is no longer an enhancement

‘Added value’ features are becoming more sophisticated
(example. Cited-by links)
 To positively influence academic standards
Many students are likely to use information found on search engines and
various Web sites as research material…and faculty often report concerns
about the number of URLs included in research paper bibliographies and the
decrease in citations from traditional scholarly sources. Pew Internet and
American Life Project College Students Survey. http://www.pewinternet.org/
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5. Topics
 What is a DOI
 Why CrossRef

How CrossRef and DOIs work

New linking features of the DOI & at CrossRef

OpenURL & CrossRef

Local Link Servers & CrossRef
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6. What is a DOI
 A Digital Object Identifier (DOI), is a unique string created to identify a
piece of intellectual property in an online environment.
 ANSI/NISO Z39.84 -2000
 The prefix is assigned by an IDF registration agency (CrossRef)
 The suffix is an opaque identifier assigned by the publisher
 Suffixes must be unique within a prefix

Some publishers use a transparent scheme
 A DOI is intended to identify a ‘work’ not a manifestation
 We’ll need multiple resolution to fully realize this goal
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7. What is CrossRef.org?
 An independent, non-profit membership organization

A cross-publisher citation linking network based on the
DOI system
 An official DOI registration agency
There are now five DOI registration agencies. CrossRef was the
first, and is the only one whose mission is to enable citation
linking and serve the scientific/scholarly community
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8. CrossRef’s Mission

To serve as the complete citation linking backbone for all scholarly
literature in electronic form, focusing on services that are best
achieved through collective agreement by publishers
– Books
– Conference proceedings
– Dissertations
– Patents
– Gray literature
– Etc…
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9. Key benefits of the CrossRef system
 As a business infrastructure for linking

No bilateral linking agreements needed – an agreement with
CrossRef is a linking agreement with all CrossRef publishers
 Publishers maintain their own business models while enhancing
value and functionality of their content

Collaborative foundation for future developments in information
access
 As a technology service

A search engine to find DOIs based on an article’s metadata
(title / author / volume / issue / page / year)

Operates an OpenURL 1.0 resolver
 As a technology provider

Standards and industry coordination

Linking expertise
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10. The CrossRef / DOI Community
CERN
…and more !!
…and more !!
…and more !!
• Gateway to the DOI world
• Develops and maintains
the DOI standard
• Develops and maintains the
Handle system upon which
the DOI executes
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11. How is CrossRef used
 by Publishers …
1. Deposit the metadata for their articles in an XML file
(Journal / Authors / Article Title / Volume / Issue /Page / Year)
2. Parse their articles and extract the elements of each reference then query
CrossRef to find the DOIs
3. Make the reference link active by using http://dx.doi.org/<some-DOI>
 May cache the DOIs for later use
 Retrieve the DOIs as needed
 by Libraries …
 Directly query CrossRef
(CERN is placing doi.crossref.org/resolve?<an-OpenURL> in their links)
 Through local link servers to ‘reverse lookup’ the metadata for a DOI
 by the public …
 Indirectly every time they follow a (CrossRef) DOI enabled link
 Find DOIs using the free lookup form at www.crossref.org
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12. What the DOI does
Provides truly persistent hyper links to the identified entities
Makes linking more reliable
Enables locating the entity through the CrossRef database
Makes linking more accessible
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13. How the DOI appears in use
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14. SSP
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15. How DOIs & CrossRef Work
HTTP://dx.doi.org/10.1016/S0040-4039(01)80789-9
Constant address DOI used to ‘lookup’
of the Resolver the entity’s URL
Publisher of the 1
1. Deposit article meta-data to
target entity
CrossRef with the DOI & URL
2 2. Query CrossRef for the DOI using
Publisher of the meta-data
referring entity 3. Present the referring article to the
user with reference links active as
3 Referrer
4 5 DOIs
Source
User 4. The user clicks on a link
5. Their browser sends the link to the
DOI Resolver
Referent 6. The Resolver finds the URL and re-
Service directs the user to the target
Target 6 document
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16. CrossRef Growth is Steady
Members Journals
300 10000
9000
250
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7000
200
6000
150 5000
4000
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Technology Blitz
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18. Queries and Matches
# of Queries Matches
16,000,000
15,000,000
14,000,000
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19. Deposits
Current Article Backfile Articles
480,000
450,000
420,000
390,000
360,000
330,000
300,000
270,000
240,000
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20. Using & Getting DOIs is free
(there is a fee for creating DOIs)
 Annual fee for libraries has been dropped immediately
 Lookup fee will be eliminated as of Jan 04
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21. Why DOIs are a good thing
 Its more than just an identifier
 A complete resolver system operated by CNRI and the RAs
 A governing body (the International DOI Foundation) for
establishing policies and to guide the maintenance, promotion
and development of the entire system.
 A tiered organization to provide support at multiple levels
IDF
RAWG CNRI
RAs RAs RAs
Prefix Prefix
Holders Holders
DOI Users DOI Users DOI Users
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22. Parameter Passing(a DOI feature)
Parameter passing
 Allows the link source to pass information through the DOI
resolver to the link target (very cool!)
 Based on OpenURL 1.0
Source
HTTP://dx.doi.org/10.1038/suffix?from=EBSCO
HTTP://dx.doi.org/10.1038/suffix?rfr_dat=cr_pub=EBSCO
With Parameter Passing and HTTP://www.nature.com/articles?id=123
With Out Parameter Passing
With
a standard vocabulary Registered URL
Target
HTTP://www.nature.com/articles?id=123
HTTP://www.nature.com/articles?rft_dat=id=123&from=EBSCO
HTTP://www.nature.com/articles?rft_dat=id=123&rfr_dat=cr_pub=EBSCO
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23. Multiple Resolution (a future DOI feature)
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24. The appropriate copy problem &
Multiple Resolution

Truly a problem seeking a multiple-resolution solution
1. Publisher A produces and hosts a journal from 1999 through 2002
2. Publisher B acquires the journal in 2003 and hosts all back issues
 Pre 2003 DOIs are transferred to publisher B and the URLs are reset
to publishers B’s
3. A customer subscribes to publisher A and wants to go there for pre-2003
issues.
 Multiple resolution of DOIs will solve this problem in the future
 Local link servers solve the problem today
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25. Multiple Resolution (cont.)
 Multiple Resolution

Infrastructure will be provide by the IDF
(browser script , server component, etc)
 Target owner can control what is displayed at the link
 Update of multiple target information done once in theDOI,
1000’s of links do not need to be touched
 3rd parties will be able to supply services as one of the choices.
(e.g. CopyRight Clearance Center’s RightsLink)
 Early forms of multiple resolution are available now
(Content Directions)
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26. Forward Linking
Cited-By Service Coming to CrossRef
 CrossRef forward linking will …
− Allow members to retrieve the DOI and extended
meta-data for the articles that cite a given article
− Utilize the same types of interfaces used with the
current service (deposit and query)
− Be built easily on top of existing member commitments
Couple meta-data deposits with DOI queries so we can
identify a reference’s source document.
 CrossRef forward linking is still under development …
− Indications are very encouraging, final approval
expected in Q3
− Fees and policies are TBD, but…
… we expect forward linking to be part of the core
CrossRef service
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27. Cited by: aka Forward Linking
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28. OpenURL and DOIs/CrossRef
OpenURL and DOI are complementary technologies

CrossRef helps solve the appropriate copy problem by
providing a ‘reverse’ DOI lookup (DOI in / meta-data out)
http://doi.crossref.org/servlet/query?id=10.1006/jmbi.2000.4282&pid=<USR>:<PWD>

CrossRef offers an OpenURL 1.0 compliant resolver
http://doi.crossref.org/resolve?pid=<USR>:<PWD>&aulast=Maas LRM
&title= JOURNAL OF PHYSICAL OCEANOGRAPHY&volume=32
&issue=3 &spage=870&date=2002
(This resolver will redirect you to the target document)
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29. What does an OpenURL look like
• Add the referent
referrer
fixed
Start with the
http://resolver.example.org?
elements
BaseURL
url_ver=z39.88-2003
&url_ctx_fmt=ori:fmt:kev:mtx:ctx Version
&rfr_id=ori:rfr:publisher.com Declare
&rft_id=ori:doi:10.1126/science.275.5304.1320 ContextObject referrer
Identifier for
format
Add the metadata
&rft_id=ori:pmid:9036860
elements
&rft_val_fmt=ori:fmt:kev:mtx:journal
&rft.genre=article Declare the
&rft.atitle=Isolation of a common receptor Include identifiers
OpenURL “Referrer” Domain of
metadata format
for … referrer
&rft.jtitle=Science (rft) format
Shows referent
(fmt) is by value (val) Indicates we are using key-
&rft.aulast=Bergelson
encoded-values (kev) as actual
Substitute
&rft.auinit=J defined in the “journal” for the item
… values matrix
(mtx) in the registry.
being referenced
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30. Why Use an OpenURL?
 OpenURL is a sophisticated (and complex) subject, but it …
 Establishes a uniform structure for the transport of meta-data and
objects
 Supports context sensitive linking (local link servers)

Supports algorithmic linking (links based on meta-data)
 OpenURL is only a specification, it is not a system
http://resolver.example.org?
A service must provide the resolver
 CrossRef operates an OpenURL 1.0 resolver:
http://doi.crossref.org/resolve?pid=<USR>:<PWD>&aulast=Maas …
 Local link servers (SFX, EBSCO’s LinkSource) are resolvers
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31. Local Link Servers
 Solves the appropriate copy problem
 Localizes control over resource linking
 Integrate with local services
 Centralizes administration
 Optimizes use of licensed resources
 Tracks resource utilization
 Linking consistency for the end users
 Often are based on OpenURL
 Algorithmic linking driven by database lookups
 Must subscribe to the vendor for database updates
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32. A&I (Ovid) as link source
Link Source
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33. OpenURL Linking: SFX & CrossRef
DOI
link
DOI
Server
References
OpenURL
http://dx.doi.org/
doi=10.1034/j.1399-0039.2000.560502.x Aware
http://www.sfx.edu/? OpenURL
doi=10.1034/j.1399-0039.2000.560502.x
Metadata
DOI Server
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34. CrossRef and Full Text Search
 Part of CrossRef’s mission statement:

Facilitate collaborative action
 Enable access for the scholar to the primary literature
 Many CrossRef members are keenly interested in a
readily accessible broad full text search service
 Two options are being considered, each have pros & cons
 Initial focus is on an ‘open’ service (very low cost,
easier to implement, lower barriers)
 Next focus is on a proprietary service that offers
more robust features specific to STM publications
 Look for an announcement before year end.
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35. www.CrossRef.org
the central source for reference linking
Linking Scholarly Communities Together
Chuck Koscher ckoscher@crossref.org
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