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

Michael Day
UKOLN, University of Bath
m.day@ukoln.ac.uk

Demonstration for the JISC Terminology Services Workshop, London, 13 February 2004

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)

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.

Participating gateways

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

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 .

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)

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 .
Link to Renardus Service

Advanced searching

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

Other options:

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

Cross-browsing

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
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.

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
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

Classification mapping

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

Mapping relationships:

Simple equivalence between terms not expected
Five mapping relationships

Fully equivalent (=)
Narrower equivalent (>)
Broader equivalent (<)
Major overlap (MJ)
Minor overlap (MN)

Syntax:

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

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
Link to image of the Renardus mapping tool

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
Link to Renardus Service

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

Browsing example

Browsing for information on 'mineralogy':
Link to Renardus Service
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 .

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

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"

Navigational support

Need for additional navigational support in large browsing structures
Renardus developed some experimental features

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
Link to Renardus Service

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
Link to Renardus Service

Merge

A short cut to viewing individual resource descriptions from all related collections
Similar to "DDC Classification" search in advanced search feature
Link to Renardus Service

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)

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

More information on Renardus:

Renardus Service:
http://www.renardus.org/
Koch, T., Neuroth, H. & Day, M. (2003). "Renardus: Cross-browsing European subject gateways via a common classification system (DDC)." In: McIlwaine, I.C. (ed.) Subject retrieval in a networked world: proceedings of the IFLA Satellite Meeting held in Dublin, OH, 14-16 August 2001. (UBCIM Publications, New Series, Vol. 25). München: K.G. Saur, 25-33. Preprint available at:
http://www.lub.lu.se/~traugott/drafts/preifla-final.html
Huxley, L., Carpenter, L. & Peereboom, M. (2003). "The Renardus broker service: collaborative frameworks and tools." Electronic Library, 21(1), 39-48.
Huxley, L. (2002). "Renardus: following the fox from project to service." In: Research and Advanced Technology for Digital Technology : 6th European Conference, ECDL 2002, Rome, Italy, September 16-18, 2002. Proceedings. (Lecture Notes in Computer Science, 2458). Heidelberg: Springer-Verlag, 218-229.
Neuroth, H. & Koch, T. (2001). "Metadata mapping and application profiles: approaches to providing the cross-searching of heterogeneous resources in the EU project Renardus." DC-2001: International Conference on Dublin Core and Metadata Applications 2001, Tokyo, Japan, 24-26 October 2001.
Available: http://www.nii.ac.jp/dc2001/proceedings/product/paper-21.pdf
Heery, R., Carpenter, L & Day, M. (2001). "Renardus project developments and the wider digital library context." D-Lib Magazine,7(4). Available: http://www.dlib.org/dlib/april01/heery/04heery.html

Web page content by Michael Day of UKOLN
Page last revised on: 16-Feb-2004

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