Cross-browsing subject gateways with the Dewey Decimal Classification in the Renardus Service

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Cross-browsing subject gateways with the Dewey
Decimal Classification in the Renardus Service

• Michael DayUKOLN, University of
  Bathm.day_at_ukoln.ac.uk
• JISC Terminology Services Workshop, London,13
  February 2004

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What is the Renardus service?

• A broker service that integrates access to
  European subject gateways
• Developed by a research project funded 2000-2002
  by the European Commission as part of the
  Information Society Technologies (IST) programme
• Managed by participating gateways through the
  Renardus Consortium
• Operational service hosted by Goettingen State
  and University Library (SUB)

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What are subject gateways?

• Discovery services that give access to
  high-quality Web resources
• Selective (defined criteria)
• Based on resource description (metadata)
• Search and browse facilities
• Use subject classification for subject browsing
• Many examples
• RDN (UK), EdNA Online (Australia), etc.

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Participating gateways
DAINet - German Agricultural Information Network DE
Denmark's Electronic Research Library (DEF) DK
DutchESS - Dutch Electronic Subject Service NL
Finnish Virtual Library (FVL), NOVAGate FI
Online dissertations (Die Deutsche Bibliothek) DE
Resource Discovery Network (RDN) UK
SSGFI gateways at SUB Goettingen (Anglistik Guide, Geo-Guide, History Guide, MathGuide) DE
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Cross-searching

• Uses the Z39.50 protocol
• Renardus application profile
• Based on the Dublin Core Metadata Element Set
  (DCMES)
• Added element
• Country
• Mandatory elements
• Identifier, Title, Description, Subject

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Search example

• Simple search for "palaeontology"
• Renardus searches each participating gateway
  using the Z39.50 protocol
• Retrieves hits from multiple gateways
• RDN (129)
• Geo-Guide (123)
• NOVAGate (2)
• DutchESS (1)
• FVL (1)
• Displays results (detailed or brief)

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Linking to resources

• The results display the URL of the described
  resource as a hyperlink
• Users can also refer to the richer metadata
  record provided by the participating gateway
• The level of detail varies
• Examples from DutchESS and RDN (Biome) follow
• Next two slides

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Record from participating gateway (DutchESS)
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Record from participating gateway (RDN Biome)
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Advanced searching (1)

• Search options
• Simple Boolean AND/OR searching on the content of
  individual elements
• Title, Subject, Description, Creator, DDC
  Classification, Document Type
• Term selection help
• For the elements Title, DDC Classification,
  Subject and Type, a "term selection window" opens
  in some browsers to indicate terms that are
  already included in gateway indexes

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Advanced searching (2)

• Other options
• Limit (filter) search by Document Type, Language,
  or Country
• Display options and search timeout
• Select which gateways to search

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Cross-browsing (1)

• Enhanced subject access a key part of the
  services offered by subject gateways
• Subject gateways, however, use many different
  subject schemes
• Some 'home-grown'
• Others based on (or adapted from) standards

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Cross-browsing (2)

• Subject schemes in use within Renardus
• Nederlandse Basisclassificatie - DutchESS
• AGRIS main subject categories - NOVAGate
• Göttinger Online-Klassifikation (GOK) -
  Geo-Guide, Anglistik Guide, History Guide
• DDC - parts of RDN
• Universal Decimal Classification (UDC) - parts of
  RDN
• Mathematics Subject Classification (MSC)
  -MathGuide
• etc.

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Cross-browsing (3)

• Also much variation in the depth of browsing
  structure (between 1 and 5 levels), although most
  are shallow
• Given this variety, how could browsing across the
  content of gateways be done in the broker
  service?
• Answer mapping local schemes to a universal
  classification scheme

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Cross-browsing (4)

• For this, the Renardus project chose the Dewey
  Decimal Classification (DDC)
• Available online (WebDewey)
• Covers all subjects, is frequently updated, has
  global use, etc.
• Negotiated a research license from OCLC Forest
  Press

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Classification mapping (1)

• General approach
• Mapping to local browse system, not to individual
  resources
• The mapping is one-way only, from the DDC to the
  local browsing system
• Mappings move from top levels of browse
  structures before moving progressively down it

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Classification mapping (2)

• Mapping relationships
• Simple equivalence between terms not expected
• Five mapping relationships
• Fully equivalent
• Narrower equivalent
• Broader equivalent
• Major overlap
• Minor overlap

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Classification mapping (3)

• Syntax
• LN (Local classification notation)LC (Local
  classification caption)RL (Relationship code,
  i.e. , gt, lt, MJ, or MN)DN (DDC notation)DC
  (DDC caption)UR (Local browsing URL for the
  class)NT (Notes)RE (Record end)

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Classification mapping (4)

• Technical solutions
• Mapping tool developed by the German CARMEN
  project (CarmenX)
• Participating gateways provide a machine-readable
  version of the classification scheme in use
• The tool (with WebDewey) facilitates the
  production of the mapping information in the
  correct syntax

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Renardus Mapping Tool
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Using the mapping information

• In Renardus, the DDC mapping information
  provides
• The basis of the cross-browse feature
• Information for the advanced search feature, e.g.
  search by DDC Classification
• The DDC browse structure forms the core part of
  the Renardus Service Web page
• Next slide

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Cross-browsing in Renardus

• Based on a two-step process
• first browsing within the DDC structure on the
  Renardus Web pages
• Then linking directly to the browse structures in
  local gateways
• Called "Browse and jump"
• Interface issues
• Visual inconsistency
• No clear path back to Renardus from the local
  gateways

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Browsing example (1)

• Browsing for information on 'mineralogy'
• Select "science" in first browse level
• Note broader equivalent mapping to "Technology
  and Natural Sciences" (DEF)
• Then select "chemistry"
• Again, note narrower and broader equivalents
• Next three slides

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Browsing example (2)

• Then select "mineralogy"
• Fully equivalent to "Mineralogy General" in GOK
  (Geo-Guide), "Mineralogy" in FVL
• A narrower equivalent is "Mineral paragenesis" in
  GOK (Geo-Guide)
• Major overlap with "Mineralogie, Boden-,
  Gesteins- und Lagerstättenkunde" in DDB online
  dissertations
• Next slide

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Browsing example (3)

• Selecting the link takes the user to the relevant
  part of the browse hierarchy in the local gateway
  
• This is known as "browse and jump"
• Examples of the relevant local browse hierarchies
  in FVL and DDB online dissertations follow
• Next two slides

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Finnish Virtual Library
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DDB
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Navigational support (1)

• Need for additional navigational support in large
  browsing structures
• Renardus developed some experimental features
• Searching for an start page
• Graphical navigation overview
• Merge

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Navigational support (2)

• Finding a different start-page
• It is possible to find a different page in the
  browse structure, by entering a term in the
  search box available on each browsing page
• This takes you to a results page that links to
  the HTML and graphical overview versions of the
  Renardus browse hierarchy
• Next three slides

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Navigational support (3)

• Graphical Navigation Overview
• Gives a 'fisheye' view of the DDC browse
  hierarchy
• Allows users to see the browse term (highlighted
  in red) together with related terms in
  surrounding classes
• Terms with content (highlighted in blue) link to
  the relevant page in the Renardus browse
  hierarchy
• Next slide

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Navigational support (3)

• Merge
• A short cut to viewing individual resource
  descriptions from all related collections
• Similar to "DDC Classification" search in
  advanced search feature
• Next two slides

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Issues

• Usability of broker
• Interface consistency
• Navigation in large structures
• Maintenance issues
• Maintenance of mappings (subject gateways are
  always changing)
• Maintenance of links to browse hierarchy in each
  gateway (e.g., when gateways restructure)

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Future developments

• Multilinguality
• Because DDC has been translated into many
  languages, it is possible to add other language
  versions of the browse system into Renardus
• Successfully implemented in the Renardus testbed
• Automatic classification
• Support for mapping process

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More information on Renardus

• Renardus Servicehttp//www.renardus.org/
• Traugott Koch, Heike Neuroth Michael Day,
  "Renardus cross-browsing European subject
  gateways via a common classification system
  (DDC)," Subject retrieval in an networked world,
  OCLC, Dublin, Ohio, August 2001http//www.lub.lu
  .se/traugott/drafts/preifla-final.html