Over the last eighteen months or so, the UK Joint Information Systems Committee (JISC) has been funding some collaborative work between the Resource Discovery Network (RDN) Hubs  and Learning and Teaching Support Network (LTSN) Centres . The primary intention of these subject-based RDN/LTSN partnerships was to:
- Develop collection policies that clarified the relationships between the two sets of activities.
- Enable the sharing of records within and beyond partnerships using the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) .
This second area of work has produced a number of technical specifications, including an 'application profile' of the IEEE Learning Object Metadata (LOM)  standard and a number of agreed vocabularies. The application profile is known as the RDN/LTSN LOM Application Profile (RLLOMAP) . The RLLOMAP and some of the vocabularies have also had input from the Learning and Teaching Portal team , and will be used as the basis for metadata sharing within that activity as well.
This article is intended to provide a technical overview of how records are being shared within the RDN/LTSN partnerships and to provide pointers to further information for those readers that want to understand the more detailed aspects of the work.
One of the key reasons for undertaking the RDN/LTSN partnership work was to encourage greater sharing of metadata records between the two services in order to build better end-user oriented services that allow people to discover learning objects and other resources more efficiently than they are able to currently. The application profile described in this document was designed to support the following kinds of searches within any services that make use of the metadata:
- Keyword searches (based on title, description and keywords in the metadata).
- Title searches (find resources with known titles).
- Author searches (find resources by known authors).
Furthermore, services will be able to filter the results of those searches based on:
- The publisher (e.g. only display resources published by the University of Bath).
- The resource language (e.g. only display resources that are written in English).
- Educational level (e.g. only display resources that are appropriate for use in FE).
Services will be able to offer browse interfaces based on:
- Subject classification.
- Educational level.
When resource descriptions are displayed, services will be able to show the following information (in addition to title, author, publisher, keywords and description):
- Copyright information.
- Resource type.
- Platform requirements.
- Annotations about using the resource in a teaching and learning situation.
The partnership work has selected and/or developed a number of technical solutions intended to meet the functional requirements outlined above. These solutions fall into five broad areas:
- A metadata schema (an 'application profile' and an XML binding) that supports the encoding of metadata records.
- A transport protocol (in order to exchange the metadata records between services).
- Vocabularies (to ensure a greater level of consistency in the values being assigned during cataloguing).
- Identifier guidelines (for both metadata records and the resources they describe).
- Cataloguing guidelines (to ensure consistent usage of the metadata schema).
Each of these areas is discussed in more detail below.
The partnership work chose to base its metadata schema on the LOM because one of the main focuses of the work was to share metadata about learning objects. Coincidentally, at the same time that the partnership work was starting, staff at CETIS were collaborating with staff at Learning and Teaching Scotland  and others in the development of a UK-specific application profile of the LOM, now known as the UK LOM Core .
The aim of the UK LOM Core is to promote common practice in the implementation of the LOM in UK educational contexts, and to align this with important international implementations. The basis of the work was a comparison of twelve metadata schemas based on the LOM, including those produced by the National Learning Network , and University for Industry  in the UK; and SCORM  and CanCore  internationally. The result is a recommended minimum core set of metadata elements that are widely used in application profiles of the LOM and some associated vocabularies that are suitable for use in all levels of UK education. Inclusion of these elements in local application profiles of the LOM will increase the opportunity for metadata sharing with other projects with minimal additional overheads by way of inclusion of elements that would not otherwise have been used.
It therefore seemed sensible to align these two bits of work. As a result, the RLLOMAP is compliant with both the UK LOM Core and with the LOM itself.
Full details of the RLLOMAP are available in the RDN/LTSN LOM Application Profile specification. A summary list of the elements that are used is shown here:
- 1.1 general.identifier
- 1.2 general.title
- 1.3 general.language
- 1.4 general.description
- 1.5 general.keyword
- 1.6 general.coverage
- 2.3 lifeCycle.contribute
- 3.1 metaMetadata.identifier
- 3.2 metaMetadata.contribute
- 3.3 metaMetadata.metadatascheme
- 3.4 metaMetadata.language
- 4.1 technical.format
- 4.2 technical.size
- 4.3 technical.location
- 4.6 technical.otherPlatformRequirements
- 5.2 educational.learningResourceType
- 5.6 educational.context
- 5.10 educational.description
- 6.2 rights.copyrightAndOtheRrestrictions
- 6.3 rights.description
- 7.1 relation.kind
- 7.2 relation.resource
- 8.3 annotation.description
- 9.1 classification.purpose
- 9.2 classification.taxonPath
It is worth noting that within the RDN hubs, most resource description is based on the Dublin Core Metadata Element Set (DCMES) . It has therefore been necessary to map the elements listed above to the DCMES. Two simple mapping tools based on XSLT were also developed. Furthermore, two bindings of the RLLOMAP have been defined, one based on the XML binding of the LOM and one based on an XML binding of Dublin Core. In the main, it is expected that most services will be based on the LOM binding. Examples of the two bindings can be seen in the 'Example' section below.
A decision was made to adopt a harvesting approach to sharing metadata records within the partnerships. This follows existing practice in the RDN, where metadata records are harvested from all the RDN hubs into a central database of all records known as ResourceFinder.
The OAI-PMH is well designed to support such a harvesting arrangement. Although it mandates support for simple Dublin Core metadata records, the OAI-PMH supports the exchange of any metadata that can be encoded using XML and for which there is a valid XML Schema definition.
One of the problems of sharing metadata based on the LOM (such as the RLLOMAP) is that the IEEE standard for an XML binding of the LOM is not yet complete, however a draft version is available. It is therefore not necessary to define a new XML schema for the RLLOMAP, the draft LOM XML schema  can be used directly. (Actually, in practice this was not quite true. One or two minor problems with the draft IEEE XML schemas required us to host locally modified copies of the XML schemas on the RDN Web site).
The OAI-PMH will also be used to exchange records between the RDN hubs and LTSN centres and the LTSN Learning and Teaching Portal, as can be seen in the diagram below:
It should be noted that the overall architecture does not specify which services should harvest which records from which other services. Nor does it indicate how often harvesting should happen. The RDN hubs and LTSN centres make these decisions as part of their collection and service development policies. The architecture simply provides the framework that allows harvesting to take place, if it is deemed to be necessary.
The partnerships have developed or adopted a number of vocabularies in order to ensure a greater level of consistency in the values being assigned during cataloguing:
Three vocabularies, intended to be used in combination, used to indicate the type or genre of resource.
A high-level list of geographic areas in the UK.
A vocabulary of pedagogic styles.
A vocabulary of educational policy themes.
Two vocabularies that provide high-level subject terms.
A list of high-level UK educational levels.
A list of high-level UK educational contexts.
Identifiers and linking
The issue of how to assign identifiers to both metadata records and the objects they describe has been fairly problematic during the partnership work. Because the RDN hubs and LTSN centres are, (in the main), describing other people's resources, the following questions are highly relevant:
- "Who is responsible for assigning an identifier to a resource?"
- "How do you tell if an identifier has already been assigned by another hub or centre?"
- "What kinds of identifiers should be used?"
- "How much modification of a record is required before a new identifier should be assigned to it?"
- "Do physical learning objects have specific identification requirements?"
These are complex issues and it would be disingenuous to claim that they are fully solved. However, some decisions naturally fall out of the choice of using the OAI-PMH as the transport protocol. For example, in supporting the OAI-PMH, each RDN hub and LTSN centre must assign a unique identifier to each of its metadata records. A decision was made to use the OAI Identifier format  for this purpose, as recommended by the protocol.
Once a unique identifier is assigned to each metadata record, it is theoretically possible to use it to assign an identifier automatically to the resource it describes. This is the approach taken by the PURL-based Object Identifier (POI) , which offers an automated way of assigning and resolving a Persistent Uniform Resource Locator (PURL)  for each resource with minimal costs to the assigner, because an OAI Identifier has already been assigned to the metadata record about the resource.
It is desirable that each resource have only one identifier in the POI scheme, therefore it follows that only the first person to describe a resource should assign a POI as described above. In order to allow RDN hubs and LTSN centres to see if a POI has already been assigned to a resource, a POI look-up service  has been developed.
For physical learning objects like books, journal articles, videos, etc., simply assigning a POI to the resource is not altogether helpful to the end-user because physical resources cannot be retrieved across the network. In this scenario, RDN hubs and LTSN centres will generate an OpenURL  for the physical resource (encoded in the 4.3 technical.location element). This will allow the end-user to move seamlessly to an OpenURL resolver, which can provide context-sensitive links to any copies of the resource that are available to them.
Information and guidelines about the above issues have been brought together in the RDN/LTSN LOM Application Profile Compliance Guidelines . The guidelines are intended to encourage a more consistent approach to describing resources by the cataloguer, and a more consistent way of encoding that information in the XML binding of LOM by software developers.
By way of example, there follows a relatively simple metadata record that describes a 'learning path' through the Wilfred Owen Multimedia Digital Archive (WOMDA) , encoded using both the XML LOM binding and the Dublin Core binding.
Firstly, here is the LOM binding:
<?xml version="1.0" encoding="UTF-8" ?> <!-- oai:rdn.ac.uk:12345-67890 --> <lom xmlns="http://ltsc.ieee.org/xsd/LOMv1p0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://ltsc.ieee.org/xsd/LOMv1p0 http://www.rdn.ac.uk/oai/lom/lom.xsd"> <general> <identifier> <catalog>URI</catalog> <entry>http://purl.org/poi/rdn.ac.uk/12345-67890</entry> </identifier> <title> <string language="en-GB">Wilfred Owen and Realism</string> </title> <language>en-GB</language> <description> <string language="en-GB"> This pathway should be of use to anyone studying Wilfred Owen at CSE (or High school level in the US). By looking at visual and other evidence in the Wilfred Owen Multimedia Digital Archive (WOMDA), it aims to raise the issue of realism in Owen's verse. </string> </description> <keyword> <string language="en-GB"> Owen, Wilfred </string> </keyword> <keyword> <string language="en-GB"> Poetry </string> </keyword> <keyword> <string language="en-GB"> Realism </string> </keyword> <keyword> <string language="en-GB"> First World War </string> </keyword> <keyword> <string language="en-GB"> WWI </string> </keyword> </general> <lifeCycle> <contribute> <role> <source>LOMv1.0</source> <value>publisher</value> </role> <entity>BEGIN:VCARD\nORG:University of Oxford\nEND:VCARD\n </entity> </contribute> <contribute> <role> <source>LOMv1.0</source> <value>author</value> </role> <entity>BEGIN:VCARD\nORG:City of London School\nEND:VCARD\n </entity> </contribute> </lifeCycle> <metaMetadata> <identifier> <catalog>URI</catalog> <entry>oai:rdn.ac.uk:12345-67890</entry> </identifier> <contribute> <role> <source>LOMv1.0</source> <value>creator</value> </role> <entity>BEGIN:VCARD\nORG:RDN\nEND:VCARD</entity> <date> <dateTime>2003-03-20</dateTime> </date> </contribute> <metadataSchema>LOMv1.0</metadataSchema> <language>en-GB</language> </metaMetadata> <technical> <format>text/html</format> <format>application/gif</format> <format>application/mpeg</format> <format>application/quicktime</format> <location>http://www.hcu.ox.ac.uk/...</location> <otherPlatformRequirements> <string language="en-GB"> Web browser </string> </otherPlatformRequirements> </technical> <educational> <learningResourceType> <source>RDNLTSNType</source> <value>Computer-basedTutorial</value> </learningResourceType> <learningResourceType> <source>DCMIType</source> <value>InteractiveResource</value> </learningResourceType> <context> <source>UKEC</source> <value>higher education</value> </context> </educational> <rights> <copyrightAndOtherRestrictions> <source>LOMv1.0</source> <value>no</value> </copyrightAndOtherRestrictions> <description> <string language="en-GB"> (c) City of London School, 2003 </string> </description> </rights> <classification> <purpose> <source>LOMv1.0</source> <value>discipline</value> </purpose> <taxonPath> <source> <string language="none">learndirect</string> </source> <taxon> <id>FC.4</id> <entry> <string language="none">English Literature</string> </entry> </taxon> </taxonPath> <taxonPath> <source> <string language="none">JACS</string> </source> <taxon> <id>Q320</id> <entry> <string language="none">English Literature</string> </entry> </taxon> </taxonPath> </classification> <classification> <purpose> <source>LOMv1.0</source> <value>educational level</value> </purpose> <taxonPath> <source> <string language="none">UKEL</string> </source> <taxon> <entry> <string language="none">level5</string> </entry> </taxon> </taxonPath> </classification> </lom>
Secondly, here's the same record encoded using the Dublin Core XML binding:
<?xml version="1.0" encoding="UTF-8" ?> <!-- oai:rdn.ac.uk:12345-67890 --> <rdndc xmlns="http://www.rdn.ac.uk/oai/rdn_dc/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:rdnterms="http://purl.org/rdn/terms/" xmlns:meg="http://purl.org/meg/terms/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.rdn.ac.uk/oai/rdn_dc/ http://www.rdn.ac.uk/oai/rdn_dc/20030323/rdn_dc.xsd"> <dc:title xml:lang="en-GB">Wilfred Owen and Realism</dc:title> <dc:language>en-GB</dc:language> <dc:description xml:lang="en-GB"> This pathway should be of use to anyone studying Wilfred Owen at CSE (or High school level in the US). By looking at visual and other evidence in the Wilfred Owen Multimedia Digital Archive (WOMDA), it aims to raise the issue of realism in Owen's verse. </dc:description> <dc:subject xml:lang="en-GB"> Owen, Wilfred </dc:subject> <dc:subject xml:lang="en-GB"> Poetry </dc:subject> <dc:subject xml:lang="en-GB"> Realism </dc:subject> <dc:subject xml:lang="en-GB"> First World War </dc:subject> <dc:subject xml:lang="en-GB"> WWI </dc:subject> <dc:publisher>University of Oxford</dc:publisher> <dc:creator>City of London School</dc:creator> <dc:format xsi:type="dcterms:IMT">text/html</dc:format> <dc:format xsi:type="dcterms:IMT">application/gif</dc:format> <dc:format xsi:type="dcterms:IMT">application/mpeg</dc:format> <dc:format xsi:type="dcterms:IMT">application/quicktime</dc:format> <dc:identifier xsi:type="dcterms:URI"> http://www.hcu.ox.ac.uk/...</dc:identifier> <dc:identifier xsi:type="dcterms:URI"> http://purl.org/poi/rdn.ac.uk/12345-67890</dc:identifier> <dc:type xsi:type="rdnterms:RDNLTSNType"> Computer-basedTutorial</dc:type> <dc:type xsi:type="dcterms:DCMIType"> InteractiveResource</dc:type> <dcterms:educationLevel xsi:type="meg:UKEL"> level5</dcterms:educationLevel> <dc:rights xml:lang="en-GB"> (c) City of London School, 2003</dc:rights> <dc:subject xsi:type="rdnterms:Learndirect"> English literature, FC.4</dc:subject> <dc:subject xsi:type="rdnterms:JACS"> Q320 English Literature</dc:subject> </rdndc>
Readers are recommended to start with the RDN/LTSN technical FAQ  - to get an overview of what is happening with this work. The FAQ covers a range of issues, such as the assignment of OAI item identifiers, the assignment of resource identifiers, workflow issues as records are shared between partners, the use of OpenURL for physical resources, etc.
The work described in this article has been undertaken by many members of the RDN and LTSN communities, through face-to-face meetings and discussion on the email@example.com mailing list. There are too many to list individually.
- Resource Discovery Network http://www.rdn.ac.uk/
- Learning and Teaching Support Network http://www.ltsn.ac.uk/
- Open Archives Initiative Protocol for Metadata Harvesting http://www.openarchives.org/
- IEEE Learning Object Metadata (LOM) http://ltsc.ieee.org/wg12/
- RDN/LTSN LOM Application Profile http://www.rdn.ac.uk/publications/rdn-ltsn/ap/
- Learning and Teaching Portal http://www.ltsn.ac.uk/genericcentre/index.asp?id=18262
- Learning and Teaching Scotland http://www.ltscotland.org.uk/
- UK LOM Core http://www.cetis.ac.uk/profiles/uklomcore
- National Learning Network http://www.nln.ac.uk/
- University for Industry http://www.ufi.com/
- ADL SCORM http://www.adlnet.org/
- CanCore http://www.cancore.ca/
- Dublin Core Metadata Element Set (DCMES) http://dublincore.org/documents/dces/
- XML schema for the LOM http://www.cs.kuleuven.ac.be/~erikd/LOM/
- RDN/LTSN learning resource type vocabulary http://www.rdn.ac.uk/publications/rdn-ltsn/types/
- RDN resource types http://www.rdn.ac.uk/publications/cat-guide/types/
- DCMI type vocabulary http://dublincore.org/documents/dcmi-type-vocabulary/
- LTSN geographic coverage vocabulary http://www.rdn.ac.uk/publications/rdn-ltsn/geographic-coverage/
- LTSN pedagogic terms vocabulary http://www.rdn.ac.uk/publications/rdn-ltsn/pedagogic-terms/
- LTSN policy themes vocabulary http://www.rdn.ac.uk/publications/rdn-ltsn/policy-themes/
- Joint Academic Coding System (JACS) http://www.hesa.ac.uk/jacs/completeclassification.htm
- learndirect Classification System (LDCS)
- UK Educational Levels (UKEL) http://www.ukoln.ac.uk/metadata/education/ukel/
- UK Educational Contexts (UKEC) http://www.ukoln.ac.uk/metadata/education/ukec/
- OAI Identifier format http://www.openarchives.org/OAI/2.0/guidelines-oai-identifier.htm
- PURL-based Object Identifier (POI) http://www.ukoln.ac.uk/distributed-systems/poi/
- PURL http://purl.org/
- POI look-up service http://www.rdn.ac.uk/poi/
- OpenURL http://www.niso.org/committees/committee_ax.html
- RDN/LTSN LOM Application Profile Compliance Guidelines http://www.ltsn-01.ac.uk/interoperability/compliance_guidelines
- A 'learning path' through the Wilfred Owen Multimedia Digital Archive (WOMDA)
- RDN/LTSN Partnerships http://www.rdn.ac.uk/publications/rdn-ltsn/
- RDN/LTSN technical FAQ http://www.rdn.ac.uk/publications/rdn-ltsn/faq/