The Dublin Core Metadata Initiative: Cross-domain resource description and resource discovery OASIS Symposium on Reliable Infrastructures for XML, April

The Dublin Core Metadata Initiative: Cross-domain resource description and resource discovery

OASIS Symposium on Reliable Infrastructures for XML, April 27, 2004, New Orleans, LA

William E. Moen<[email protected]>

School of Library and Information SciencesTexas Center for Digital Knowledge

University of North TexasDenton, TX 72603

Moen OASIS Symposium on Reliable Infrastructures for XML--April 27, 2004--New Orleans 2

Road map

Some terminology Overview of Dublin Core Selected implementations and applications


Terminology

Metadata The result of processes (manual or automatic) performed on an

object, where the result is a representation or derivative of the salient features of the object

Descriptive information about an object or resource whether it be physical or electronic

Can serve many and multiple purposes Resource description

Metadata used to create resource descriptions, e.g., library catalog records, of information objects

Resource discovery Metadata used to assist people in finding, identifying, selecting,

and accessing information objects


Terminology

Information organizationThe processes and practices of describing and representing information objects (containers and content), and identifying the connections and relationships between the objects and the people responsible for their creation and/or production.

Purpose of information organizationThese processes and practices serve users by assisting them to identify, locate, access, retrieve, and make judgments about information in response to their information needs.


Dublin Core Metadata Initiative

Dublin Core Metadata Initiative (DCMI) An organization dedicated to fostering the widespread adoption of

interoperable metadata standards and promoting the development of specialized metadata vocabularies for describing resources to enable more intelligent resource discovery systems

Mission Make it easier to find resources using the Internet through the

following activities:• Developing metadata standards for discovery across domains • Defining frameworks for the interoperation of metadata sets• Facilitating the development of community- or disciplinary-specific metadata

sets that are consistent with items 1 and 2


Dublin Core Metadata Element Set

Dublin Core Metadata Element Set (DCMES) A set of 15 descriptive semantic definitions A core set of elements that could be shared across disciplines or

within any type of organization needing to organize and classify information

Three formally endorsed versions the Dublin Core Metadata Element Set, version 1.1: ISO Standard 15836-2003 (February 2003) NISO Standard Z39.85-2001 (September 2001) CEN Workshop Agreement CWA 13874 (March 2000) Internet RFC 2413 (September 1998): first published version of the

Dublin Core; superseded by the above three standards


Design goals for DCMES Simplicity of creation and maintenance

Define a small and simple metadata element set to allow a non-specialist to create simple descriptive records for information resources easily and inexpensively while providing for effective retrieval of those resources in the networked environment.

Commonly understood semantics Provide a common set of elements, the semantics of which are

universally understood and supported. International scope

Involve representatives from virtually every continent to ensure the development of the standard considers the multilingual and multicultural nature of the electronic information universe.

Extensibility Provide mechanisms for extending the DC element set for

additional resource discovery needs.


The 15 elements

Type (Resource Type) Format (Format) Identifier (Resource Identifier) Source (Source) Language (Language) Relation (Relation) Coverage (Coverage) Rights (Rights Management)

Title (Title): Creator (Creator) Subject (Subject and

Keywords) Description (Description): Publisher (Publisher) Contributor (Contributor) Date (Date)

All elements are optional and repeatable


Three components for metadata

Elements & Semantics Definitions for the content of the elements, e.g., what is a title,

creator, etc. Focus of DCMES

Content Rules – Guidelines and direction for inputting the content, e.g., what to

capitalize, order of elements, etc. DCMES guidelines available

Syntax Rules for structuring and expressing the elements for machine

processing DCMES is syntax independent


Element name and semantics

Element Name: Title Label: Title Semantics: A name given to the resource. Comment: Typically, Title will be a name by which the resource is

formally known.

Element Name: Creator Label: Creator Semantics: An entity primarily responsible for making the content

of the resource. Comment: Examples of Creator include a person, an organization,

or a service. Typically, the name of a Creator should be used to indicate the entity.


DC qualifiers

To extend and refine the 15 elements Two categories of qualifiers:

Element Refinement – These qualifiers make the meaning of an element narrower or more specific. A refined element shares the meaning of the unqualified element, but with a more restricted scope.

Encoding Scheme – These qualifiers identify schemes that aid in the interpretation of an element value. These schemes include controlled vocabularies and formal notations or parsing rules.


DCMI Terms

Authoritative specification of all metadata terms related to DC, including elements, element refinements, encoding schemes, vocabulary terms

Maintained by the DC Usage Board Contained in the DCMI Metadata Registry

DC Element Element Refinements Element Encoding Schemes

Date DateCreatedValidAvailableIssuedModifiedDate CopyrightedDate Submitted

DCMI PeriodW3C-DTF


Syntax

DCMI avoided the syntax wars But interoperability? Now provides specifications for encoding DC

simple and DC qualified in: HTML <meta> elements XML according to DCMES XML schemas RDF according to DCMES RDF schemas


Application profiles Consist of data elements drawn from one or more namespace

schemas combined together by implementors and optimised for a particular local application.

Application profiles are useful as they allow the implementor to declare how they are using standard schemas

Characteristics: May draw on one or more existing namespaces Introduce no new data elements May specify permitted schemes and values Can refine standard definitions

Application profiles enable implementors “to share information about their schemas in order to inter-work with wider groupings…. Communities can start to align practice and develop common approaches by sharing their application profiles.” From Heery and Patel, 2000


Implementations and applications Gateway to Educational Materials

http://gem.syr.edu improve the organization and accessibility of collections of educational materials

Monticello Electronic Library http://www.solinet.net/preservation/preservation_templ.cfm?doc_id=1062 DC used to provide semantic interoperability between several databases of

electronic media and record types open.gov.uk

http://www.open.gov.uk First entry point to UK public sector information on the internet, uses the Dublin

Core RDF vocabulary to describe each of the resources available on the site Environment Australia

http://www.ea.gov.au/ Utilizes DC for its Web metadata and internal searches


Implementations and applications

Library Application Profile http://www.dublincore.org/documents/2002/09/24/library-application-profile/ Clarifies the use of DC in libraries and library-related applications and projects

Open Archives Initiative Protocol for Metadata Harvesting http://www.openarchives.org/ Uses DC simple for exposing metadata for harvesting

Search and Retrieve Web Service http://www.loc.gov/srw An XML-based protocol that uses DC as one of the XML schemas to transfer

information from database to client


Metadata packages and METS

Metadata Encoding and Transmission Standard (METS)

A digital library standard for encoding descriptive, administrative, and structural metadata

Expressed using the XML schema language

Dublin Core is not intended to displace any other metadata standard. Rather it is intended to co-exist — often in the same resource description — with metadata standards that offer other semantics. It is fully expected that descriptive records will contain a mix of elements drawn from various metadata standards, both simple and complex.

from ANSI/NISO Z39.85


METS structure METS Header: Contains metadata describing the METS document

itself Descriptive Metadata: May point to descriptive metadata external

to the METS document or contain internally embedded descriptive metadata, or both.

Administrative Metadata: Provides information regarding how the files were created and stored, intellectual property rights, etc.

File Section: Lists all files containing content which comprise the electronic versions of the digital object.

Structural Map: Outlines a hierarchical structure for the digital library object, and links the elements of that structure to content files and metadata that pertain to each element.

Structural Links: Records the existence of hyperlinks between nodes in the hierarchy outlined in the Structural Map.

Behavior: A behavior section can be used to associate executable behaviors with content in the METS object


DC & Admin MD in METS document<dmdSec ID="dmd002"> <mdWrap MIMETYPE="text/xml" MDTYPE="DC" LABEL="Dublin Core Metadata"> <xmlData> <dc:title>Alice's Adventures in Wonderland</dc:title> <dc:creator>Lewis Carroll</dc:creator> <dc:date>between 1872 and 1890</dc:date> <dc:publisher>McCloughlin Brothers</dc:publisher> <dc:type>text</dc:type> </xmlData> </mdWrap> </dmdSec>

<techMD ID="AMD001"> <mdWrap MIMETYPE="text/xml" MDTYPE="NISOIMG" LABEL="NISO Img. Data"> <xmlData> <niso:MIMEtype>image/tiff</niso:MIMEtype> <niso:Compression>LZW</niso:Compression> <niso:ScanningAgency>NYU Press</niso:ScanningAgency> </xmlData> </mdWrap> </techMD>


Summary

Metadata is critical for: Resource description Resource discovery Management of information resources

DCMI provides international forum for identifying problems, developing understanding, and proposing solutions.

DCMES provides metadata solutions For simple resource description that can be extended for richer

resource representations For interoperability of metadata through a system of common

semantics and prescribed syntaxes For expressing queries using common search concepts across

domains


References Dublin Core Metadata Initiative

http://www.dublincore.org ANSI/NISO Z39.85-2001: The Dublin Core Metadata Element Set

http://www.niso.org/standards/resources/Z39-85.pdf DCMI Frequently Asked Questions

http://www.dublincore.org/resources/faq/ Using Dublin Core (D. Hillmann)

http://dublincore.org/documents/usageguide/ DCMI Schemas (XML and RDF)

http://dublincore.org/schemas/ Application Profiles: Mixing and Matching Metadata Schemas

(R. Heery and M. Patel) http://www.ariadne.ac.uk/issue25/app-profiles/

Dublin Core Projects http://dublincore.org/projects/

Documents

The Dublin Core Metadata Initiative: Cross-domain resource description and resource discovery OASIS Symposium on Reliable Infrastructures for XML, April