dublin core, oai-pmh and the ebank uk schema monica duke m.duke@ukoln.ac.uk ukoln, university of...

Dublin Core, OAI-PMH and the eBank UK schema

Monica Dukem.duke@ukoln.ac.uk

UKOLN, University of Bath, UKhttp://www.ukoln.ac.uk/

UKOLN is supported by:

eBank UK workshop on Chemistry schemasUniversity of Bath, 18th February 2005

Contents

• Whirlwind guide to DC• DC abstract model• Encoding in XML

• OAI-PMH and the eBank UK project• eBank UK XML schema definition• Crystallography suggestions

Note: you are going to see some angle-brackets

Acknowledgement

• Andy Powell (UKOLN)• For donation of slides

• Recommendation• Dublin Core Conference Tutorials • (Oct 04)• http://www.ukoln.ac.uk/metadata/

presentations/ecdl-2004/dc-tutorial/

Bluffer’s guide to DC

1. DC short for Dublin Core

2. simple metadata standard,supporting ‘cross-domain’resource discovery

3. original focus on Web resources but that is no longer the case – e.g. usage to describe physical artefacts in museums

4. current usage across wide range of sectors – academic, e-government, museums, libraries, business, semantic Web

http://dublincore.org/http://dublincore.org/

Bluffer’s Guide to DC

• ‘simple DC’ provides 15 elements (metadata properties)

• multiple encoding syntaxes including HTML <meta> tags, XML and RDF/XML (XML schema are available)

dc:title dc:contributor dc:source

dc:creator dc:date dc:language

dc:subject dc:type dc:relation

dc:description dc:format dc:coverage

dc:publisher dc:identifier dc:rights

7. relatively slow programme of adding new terms to ‘qualified DC’• new elements (e.g.

dcterms:audience)• element refinements (e.g.

dcterms:dateCopyrighted)• encoding schemes (e.g.

dcterms:LCSH and dcterms:W3CDTF• 48 elements and 17 encoding

schemes

http://dublincore.org/documents/dcmi-terms/http://dublincore.org/documents/dcmi-terms/

8. DC can be embedded into HTML pages but almost none of the big search engines will use it! Why? Lack of trust…• meta-spam• meta-crap• however, embedding DC in HTML may be

worthwhile if your own site search engine uses it

9. however, simple DC forms baseline metadata format for the OAI protocol.

Important DCMI documents…• DCMI Abstract Model – DRAFT

http://www.ukoln.ac.uk/metadata/dcmi/abstract-model/

• Expressing Dublin Core in HTML/XHTML meta and link elementshttp://dublincore.org/documents/dcq-html/

• Guidelines for implementing Dublin Core in XMLhttp://dublincore.org/documents/dc-xml-guidelines/

• Expressing Simple Dublin Core in RDF/XMLhttp://dublincore.org/documents/dcmes-xml/

• Expressing Qualified Dublin Core in RDF/XMLhttp://dublincore.org/documents/dcq-rdf-xml/

• Namespace Policy for the DCMIhttp://dublincore.org/documents/dcmi-namespace/

• DCMI Metadata Termshttp://dublincore.org/documents/dcmi-terms/

Abstract models for DC

Why an abstract model?

• Before we start creating DCMI descriptions we need to understand what kinds of things we want to say about ‘resources’

• the DCMI view of the world/resources we want to describe (the DCMI resource model)

• the DCMI view of the descriptions we make about that world (the DCMI description model)

• Known as the DCMI abstract model• Simplified view presented here

What is a resource?

• W3C/IETF definition of resource is“…anything that has identity. Familiar examples include an

electronic document, an image, a service (e.g., "today's weather report for Los Angeles"), and a collection of other

resources. Not all resources are network "retrievable"; e.g., human beings, corporations, and bound books in a library can

also be considered resources.”

• i.e. a resource is “anything”• physical things (books, cars, people)• digital things (Web pages, digital images)• conceptual things (colours,

points in time)

DC and resources

• but… this seems to be too wide for the things we can describe with DC!

• can we really describe people using DC?• do people have titles and subjects?

• no… in general we only use DC to describe a sub-set of all resources

• anything covered by the DCMIType list…• Collection, Dataset, Event, Image (Still or

Moving), Interactive Resource, Service, Software, Sound, Text, Physical Object

DCMI resource model

• each resource that we want to describe has zero or more properties

• a property is a specific aspect, characteristic, attribute or relation used to describe a resource

• each property has one or more values• each value is a resource (the physical or

conceptual entity that is associated with a property when it is used to describe a resource)

DCMI description model

• a description is made up of• one or more statements (about one, and only one,

resource) and• zero or one resource URI (a URI reference that

identifies the resource being described)

• each statement is made up of• a property URI (that identifies a property),• zero or one value URI (that identifies a value of the

property),• zero or one encoding scheme URI (that identifies

the class of the value) and• zero or more value representations of the value

DCMI description model (2)

• each property is an attribute of the resource being described

• each property URI may be repeated in multiple statements

• the value representation may take the form of a value string, a rich value or a related description

• Value string • is a simple human-readable string• May have an associated language (e.g.en-

The 1:1 principle

• notice that the model indicates that each property used in a description must be an attribute of the resource being described

• this is commonly referred to as the 1:1 principle - the principle that a DCMI metadata description describes one, and only one, resource

• however…

Description sets

• real-world metadata applications tend to be based on loosely grouped sets of descriptions (where the described resources are typically related in some way)

• known here as description sets• for example, a description set might

comprise descriptions of both a painting and the artist

DCMI records

• description sets are instantiated, for the purposes of exchange between software applications, in the form of metadata records

• each record conforms to one of the DCMI encoding guidelines (XHTML meta tags, XML, RDF/XML, etc.)

<dc:title>a document</dc:title><dc:creator>andy powell</dc:creator>

Model summaryrecord (encoded as XHTML, XML or RDF/XML)

description set

description (about a resource (URI))

statement

property (URI) value (URI)

representation

value string

OR rich value

OR related description

vocabulary encoding scheme (URI)

syntax encodingscheme (URI)

language(e.g. en-GB)

Simple and qualified

• a simple DC record is a record that: • conforms to the abstract model,• comprises only a single description,• uses only the 15 properties in the Dublin

Core Metadata Element Set,• makes no use of value URIs, encoding

schemes, rich values or related descriptions.

Simple and qualified DC

• a simple DC record is a record that: • conforms to the abstract model,• comprises only a single description,• uses only the 15 properties in the Dublin

Core Metadata Element Set,• makes no use of value URIs, encoding

schemes, rich values or related descriptions.

Qualified DC model

• a qualified DC record is a record that: • conforms to the DCMI abstract model,• contains at least one property taken

from the DCMI Metadata Terms recommendation

A couple of notes…

• everything in DC is optional• Dumb-down

• the process of translating a qualified DC metadata record into a simple DC metadata record

• informed dumb-down• uninformed dumb-down

Encoding DC in XML

DCMI recommendations

• For the full details:

Guidelines for implementing Dublin Core in XMLhttp://dublincore.org/documents/dc-xml-guidelines/

• nine recommendations for encoding DC in XML

General Recommendations

• implementers should base their XML applications on XML Schemas rather than XML DTDs

• Use of upper and lower case in property names and encoding schemes

e.g. property names for the 15 DCMES elements should be lower-case <dc:title>

Properties and values

• implementers should encode properties as XML elements and values as the content of those elements

• the name of the XML element should be an XML qualified name (QName) of the property

<dc:title>Dublin Core in XML</dc:title>

• do not use constructs like

<dc:title value="Dublin Core in XML" />

Repeating Properties

• multiple value strings should be encoded by repeating the XML element for that property

<dc:title>First title</dc:title> <dc:title>Second title</dc:title>

Value String language

• where the language of the value is indicated, it should be encoded using the ‘xml:lang’ attribute

<dc:subject xml:lang="en"> seafood</dc:subject><dc:subject xml:lang="fr"> fruits de mer</dc:subject>

Container elements

• note that it is anticipated that records will be encoded within one or more container XML element(s) of some kind

• candidate container element names include <dc>, <dublinCore>, <resource>, <record> and <metadata>

Element Refinements• element refinements should be treated in the

same way as other properties• the name of the XML element should be an XML

qualified name (QName):

<dcterms:available>2002-06</dcterms:available>

• do not use any of the following:

<dc:date refinement="available">2002-06</dc:date><dc:date type="available">2002-06</dc:date><dc:date> <dcterms:available>2002-06 </dcterms:available></dc:date>

Encoding schemes

• encoding schemes should be implemented using the 'xsi:type' attribute of the XML element for the property

• the name of the encoding scheme should be given as the attribute value, and should be in the form of an XML qualified name (QName):

<dc:identifier xsi:type="dcterms:URI"> http://www.ukoln.ac.uk/</dc:identifier>

OAI-PMH

• OAI Protocol for Metadata Harvesting• simple protocol for sharing metadata records

between applications• currently at version 2.0• based on HTTP, XML, XML Schema and XML

namespaces• allows a harvester to ask a remote repository for

some or all of its metadata records• where ‘some’ is based on date-stamps, sets,

metadata formats

http://www.openarchives.org/http://www.openarchives.org/

OAI-PMH (2)

• OAI-PMH carries only metadata• content (e.g. full-text or image) made

available separately – typically at URL in metadata

• simple DC is default (mandatory) record format

• supports any record format provided it can be encoded using XML (e.g. DC, IMS, MARC, ODRL, …)

OAI-PMH model

OAI-PMH identifier

= entry point to all records pertaining to the resource

resource

Dublin Core Metadata

recordsMARC Metadata

Crystal Structure Report

Jump-off page (HTML)

Model adapted from: http://www.dlib.org/dlib/december04/vandesompel/12vandesompel.htmlModel adapted from: http://www.dlib.org/dlib/december04/vandesompel/12vandesompel.html

Data Flow in eBank UK

Submit

Store/link

Data files

Metadata

present

HTMLInstitutional repository

Harvest (XML)

Index and Search

present

eBank aggregator

create

OAI-PMH model

OAI-PMH identifier

resource

recordsIMS Metadata

<dc:identifier>Linking <a href= >

typetypeDate createdDate created

<dc:identifier><dc:identifier>

1:1 principle 1:1 principle

OAI-PMH outline record <record>

<identifier>oai:ecrystals.chem.soton.ac.uk:27</identifier>

</header>

<ebank:ebank_dc xsi:schemaLocation="http://www.rdn.ac.uk/oai/ebank_dc/ http://www.rdn.ac.uk/oai/ebank/20040611/ebank_dc.xsd">

<dc:identifier xsi:type="dcterms:URI">

http://ecrystals.chem.soton.ac.uk/archive/00000027/

</dc:identifier>

</metadata>

</record>

</dc:identifier>

http://ecrystals.chem.soton.ac.uk/archive/00000027/#cif

</dc:identifier>

</metadata>

</record>

<!– Need a wrapper here

</dc:identifier>

http://ecrystals.chem.soton.ac.uk/archive/00000027/#cif

</dc:identifier>

<!– insert end wrapper here

</metadata>

</record>

Wrapper choices

• Invent our own• Re-use a packaging standard

• Choice from MPEG_DIDL, METS, IMS• METS preliminary use

– Free– Innate support for DC– Dig-lib currency

• Increasing interest in packaging formats in the OAI-PMH community

For Links see:http://www.dlib.org/dlib/december04/vandesompel/12vandesompel.html

Using packaging<metadata>

<!– Need a wrapper here

<METS:mets xsi:schemaLocation="http://www.loc.gov/METS/ http://www.loc.gov/standards/mets/mets.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:METS="http://www.loc.gov/METS/" xmlns="http://www.loc.gov/METS/">

</dc:identifier>

<ebank:ebank_dc xsi:schemaLocation="http://www.rdn.ac.uk/oai/ebank_dc/ http://www.rdn.ac.uk/oai/ebank/20040611/ebank_dc.xsd"></ebank_dc>

OAI-PMH model

OAI-PMH identifier

resource

recordsMETS Metadata

<dc:identifier>

Linking <a href= >

Dublin Core Metadata (eBank_dc)

DC 1:1 principle DC 1:1 principle

<dc:type>Crystal Structure</dc:type>

<dc:type xsi:type=“eBankDtaasetType>CIFDataset</dc:type>

Anatomy of an eBank UK record

eBank_dc schema<ebank:ebank_dc xmlns:ebankterms="http://purl.org/ebank/terms/"

xmlns:dcterms="http://purl.org/dc/terms/" xsi:schemaLocation="http://www.rdn.ac.uk/oai/ebank_dc/ http://www.rdn.ac.uk/oai/ebank/20040611/ebank_dc.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ebank="http://www.rdn.ac.uk/oai/ebank_dc/" xmlns:dc="http://purl.org/dc/elements/1.1/"> <dc:identifier xsi:type="dcterms:URI">http://ecrystals.chem.soton.ac.uk/archive/00000027/</dc:identifier>

<dc:type >Crystal Structure</dc:type>

<dc:creator >Hursthouse, Michael B.</dc:creator>

<dc:creator >Coles, Simon J.</dc:creator>

<dc:publisher ></dc:publisher>

<dc:subject xsi:type="ebankterms:EmpiricalFormula">C14H22O6</dc:subject>

<dc:subject xsi:type="ebankterms:IUPAC">(5,2 -Dimethyl-5 -oxo-octahydro-[2, 2 ]bifuranyl-5-yl)-hydroxy-acetic acid ethyl ester</dc:subject>

<dc:subject xsi:type="ebankterms:CCDC">HUZDEL</dc:subject>

<dc:subject xsi:type="ebankterms:CompoundClass">Organic</dc:subject>

<dcterms:isReferencedBy xsi:type=“dcterms:URI”>http://scripts.iucr.org/cgi-bin/getarticleid?issn=1600-5368&volume=59&fpage=o501&details=yes</dcterms:isReferencedBy> <dcterms:available >2004-05-23</dcterms:available>

<dc:publisher >???????</dc:publisher>

<dcterms:isReferencedBy xsi:type=“dcterms:URI”>http://scripts.iucr.org/cgi-bin/getarticleid?issn=1600-5368&volume=59&fpage=o501&details=yes</dcterms:isReferencedBy>

<dcterms:available >2004-05-23</dcterms:available>

Add general subject terms e.g. Chemistry,Crystallography

Are there existing ontologies that can be re-used for general subject terms?

<dcterms:isReferencedBy xsi:type=“dcterms:URI”>http://scripts.iucr.org/cgi-bin/getarticleid?issn=1600-5368&volume=59&fpage=o501&details=yes</dcterms:isReferencedBy>

<dcterms:available >2004-05-23</dcterms:available>

eBank_dc schema (cont.)<dcterms:references xsi:type="dcterms:URI">http://ecrystals.chem.soton.ac.uk/archive/00000027/#cif</

dcterms:references> <dcterms:references xsi:type="dcterms:URI">http://ecrystals.chem.soton.ac.uk/archive/00000027/#proc</

dcterms:references> <dcterms:references xsi:type="dcterms:URI">http://ecrystals.chem.soton.ac.uk/archive/00000027/#rfne</

dcterms:references> <dcterms:references xsi:type="dcterms:URI">http://ecrystals.chem.soton.ac.uk/archive/00000027/#soln</

dcterms:references> </ebank:ebank_dc>

<ebank:ebank_dc xmlns:dcterms="http://purl.org/dc/terms/" xmlns:ebankterms="http://purl.org/ebank/terms/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ebank="http://www.rdn.ac.uk/oai/ebank_dc/" xmlns:dc="http://purl.org/dc/elements/1.1/" xsi:schemaLocation="http://www.rdn.ac.uk/oai/ebank_dc/ http://www.rdn.ac.uk/oai/ebank/20040611/ebank_dc.xsd">

<dc:type xsi:type="ebankterms:EbankDatasetType">CIFDataset</dc:type> <dc:identifier xsi:type="dcterms:URI">http://ecrystals.chem.soton.ac.uk/archive/00000027/#cif</

dc:identifier></ebank:ebank_dc>

METS Metadata

Dublin Core Metadata (ebank_dc)

Suggestions

• It useful to design two sets of metadata: • A core set expressible within the

OAI-PMH Dublin Core manifestation;

• an extended set specific to value-adding agents.

• Use OAI-PMH friends facility• Define OAI-PMH sets for crystallography

Questions?

dublin core, oai-pmh and the ebank uk schema monica duke m.duke@ukoln.ac.uk ukoln, university of...

dc slide

dc simple dc

dcmi http

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relation dc

available dc

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