Implementation Guidelines for the Open Archives Initiative Protocol for Metadata Harvesting

Conveying rights expressions in the OAI-PMH framework

Protocol Version 2.0 of 2002-06-14
Document Version 2004/06/02T16:43:00Z
http://www.openarchives.org/OAI/2.0/guidelines-rights.htm

DRAFT VERSION

Editors

The OAI Executive:
Carl Lagoze <lagoze@cs.cornell.edu> -- Cornell University - Computer Science
Herbert Van de Sompel <herbertv@lanl.gov> -- Los Alamos National Laboratory - Research Library

From the OAI Technical Committee:
Michael Nelson <m.l.nelson@larc.nasa.gov> -- NASA - Langley Research Center
Simeon Warner <simeon@cs.cornell.edu> -- Cornell University - Computer Science

This document is one part of the Implementation Guidelines that accompany the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH).

1. Introduction and Scope

The Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) provides a mechanism for data providers to expose XML-formatted data for harvesting over the web. This data is disseminated in for the form of records, the contents of which are usually XML-formatted metadata about content in the repository. This metadata can then be consumed by services (e.g., search) that process (e.g. index) that metadata for users. Other uses of OAI-PMH include dissemination of records that contain metadata collected by aggregators from other sources (frequently via OAI-PMH), non-content-oriented metadata such as usage logs, and content itself that is expressed in XML.

Regardless of the usage scenario for OAI-PMH data providers might want to associate rights expressions with the contents of records. In their simplest forms these rights expressions are statements in XML format that specify how the contents of the record may be used including how it may be shared, modified, and used as the basis for derivative products (e.g., enhanced metadata). These simple rights statements are one instance in a suite of rights management and access control techniques including restricting harvesting to authorized parties, controlling the eventual use of harvested data through technical means, and specifying and controlling the use of content referenced by the harvested metadata.

This specification is limited in scope to the simple case: it provides the syntax for packaging within the OAI-PMH responses rights statements, formatted in XML, that apply to the contents of the records harvested via the OAI-PMH. The specification makes use of existing information containers within OAI-PMH, thus making no changes to the core protocol and maintaining compatibility with all existing OAI-PMH implementations.

The mechanisms described in this specification are not tied to any particular rights expression language. Examples throughout this document make use of Creative Commons license statements, but the use of this specific language is for illustrative purposes only. The only restriction imposed by the specified technique is the use of XML as the syntax for expressing rights statements.

In this document the key words "must", "must not", " required", "shall", "shall not", "should", " should not", "recommended", "may", and "optional " in bold face are to be interpreted as described in RFC 2119 . An implementation is not conformant if it fails to satisfy one or more of the "must" or "required" level requirements for the protocols it implements.

2. Granularity of rights statements

The OAI-PMH data model includes a number of entities, some of which aggregate other entities. These entities are as follows and and illustrated in the following figure:

Repository - A network accessible server that processes OAI-PMH requests and thereby makes metadata harvestable.
Resource - The object that metadata is "about". In some cases, repositories have Resources (and associated metadata) as their constituents. In others, such as metadata aggregators, the Resource is separate from the Repository.
Item - An abstract object that represents the collection of metadata "about a Resource" that can be harvested from a Repository via the OAI-PMH.
Record - XML-encoded metadata in a specific format returned via an OAI-PMH harvesting request.
Set - A grouping of Items for the purpose of selective harvesting. Set membership for Items is not required - an Item may be in no Sets - and non-exclusive - an Item may be in more than one Set.

This document specifies the mechanisms by which rights statements can be associated with two of these entities:

Record - Metadata returned from the OAI-PMH ListRecords and GetRecords requests is packaged as an XML-formatted Record. Each record may contain one or more <about> containers that provide information about the <metadata> part of the record. This document describes a schema for a <rights> package within an <about> container that associates a rights statement with the information in the <metadata> part of the record. This rights statement may be specified in-line within a <rights> package or by-reference via a URL to a network-accessible rights statement.
Repository - The response to the OAI-PMH Identify request contains information about the repository. The response may contain one or more <description> containers, that provide an extensible mechanism for communities to describe their repositories. This document describes a schema for an optional <rightsManifest> package within a <description> container that is a manifest of the rights statements that apply to records disseminated by the repository. A data provider may choose to implement this feature as a convenience for harvesting clients. In addition, the <rights> packages disseminated within the <about> containers of records returned from ListRecords and GetRecords requests may reference via URL the rights statements in this manifest. This gives data providers the convenience of managing all rights statements for a repository in a single list.

Details on each of these mechanisms are described in the following sections.

3. XML schema to package a rights statement in the "about" part of a record

.The schema shown below provides the format for encapsulating a single <rights> statement within an <about> container associated with a record returned from a ListRecords and GetRecords request. The schema provides two mutually exclusive alternatives for specifying the rights statement:

in-line: The rights statement may be contained in XML syntax within the <rights> element. The elements of the rights statement must be defined in a namespace distinct from the OAI elements and may be subject to validation to external schema. Otherwise, the nature of the rights statement is undefined by this schema.
by-reference: The rights statement may be referenced via a URL contained with the <rights> element. There are no restrictions on the nature of the resource referenced by this URL. However, to facilitate machine processing, the recommended format for referenced rights statements is XML. Data providers that disseminate records with by-reference rights statements should be aware of persistence issues related to URL references. Specifically, the possible latency between the dissemination of a record with a referenced rights statement and the eventual use of that record, and resolution of the reference, may result in a failed reference or even a reference to a changed rights statement with different meaning. Therefore, it is recommended that data providers concerned with truly static rights statements employ the in-line method.

In both cases, the rights statement (either explicit or referenced) applies to the contents of the <metadata> element of the record, rather than to any resource referenced by the contents of the <metadata> element.

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="http://www.openarchives.org/OAI/2.0/Rights/Record" 
    xmlns="http://www.openarchives.org/OAI/2.0/Rights/Record" 
    xmlns:xs="http://www.w3.org/2001/XMLSchema" 
    elementFormDefault="qualified" attributeFormDefault="unqualified">
  <xs:element name="rights" type="rightsStatementType"/>
  <xs:complexType name="rightsStatementType">
    <xs:choice>
      <xs:element name="rightsReference">
        <xs:complexType>
          <xs:attribute name="ref" type="xs:anyURI" use="required"/>
        </xs:complexType>
      </xs:element>
      <xs:element name="rightsDefinition">
        <xs:complexType>
          <xs:sequence>
            <xs:any namespace="##other"/>
          </xs:sequence>
        </xs:complexType>
      </xs:element>
    </xs:choice>
  </xs:complexType>
</xs:schema>

This Schema is available at http://www.openarchives.org/OAI/2.0/RecordRightsPackage.xsd

The following example shows the use of this <rights> container to package an in-line rights statement. The rights statement listed in this example is the RDF/XML for the Creative Commons license that can be displayed in human-readable form at http://creativecommons.org/licenses/by/2.0/.

<about>
  <rights xmlns="http://www.openarchives.org/OAI/2.0/Rights/Record"  
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/Rights/Record
      http://www.openarchives.org/OAI/2.0/RecordRightsPackage.xsd">
    <rightsDefinition>
        <rdf:RDF xmlns="http://web.resource.org/cc/" 
           xmlns:dc="http://purl.org/dc/elements/1.1/" 
           xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
          <Work rdf:about="">
            <dc:type rdf:resource="http://purl.org/dc/dcmitype/Text"/>
            <license rdf:resource="http://creativecommons.org/licenses/by/2.0/"/>
          </Work>
          <License rdf:about="http://creativecommons.org/licenses/by/2.0/">
            <permits rdf:resource="http://web.resource.org/cc/Reproduction"/>
            <permits rdf:resource="http://web.resource.org/cc/Distribution"/>
            <requires rdf:resource="http://web.resource.org/cc/Notice"/>
            <requires rdf:resource="http://web.resource.org/cc/Attribution"/>
            <permits rdf:resource="http://web.resource.org/cc/DerivativeWorks"/>
          </License>
        </rdf:RDF>
      </rightsDefinition>
  </rights>
</about>

The following example shows the use of this <rights> container to package a by-reference rights statement.

<about>
  <rights xmlns="http://www.openarchives.org/OAI/2.0/Rights/Record"  
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/Rights/Record
      http://www.openarchives.org/OAI/2.0/RecordRightsPackage.xsd">
    <rightsReference ref="http://creativecommons.org/licenses/by/2.0/"/>
  </rights>
</about>

4. XML schema to package rights statements in the "description" part of an Identify response

Implementations may include a <rightsManifest> package within the <description> element returned as part of an Identify response. This optional package can serve two purposes:

It acts as a manifest of the rights statements that apply to records disseminated by the repository. One typical use of this manifest is the case where all records disseminated by the repository are covered by a small set of rights statements (e.g. less than ten). When this small set of rights statements are packaged as a manifest within the Identify response, harvesting clients can quickly determine the rights issues that encumber the records disseminated by the repository and decide whether to proceed with harvesting records. While the completeness and correctness of this manifest is not mandated by the protocol, it is highly recommended that data providers maintain its accuracy since its contents may effect decisions by clients to harvest contained metadata.
It provides an end point for by-reference rights statements in the "about" part of a record. This gives data providers the convenience of managing all rights statements for a repository in a single list, assigning unique IDs to each of those rights statements, and referencing them via this unique ID. Data providers that include these types of references should be aware of persistence issues related to these references. Specifically, the possible latency between the dissemination of a record that references a rights statement in this manifest and the eventual use of that record, and resolution of the reference, mandates that the data provider should maintain the integrity of the reference (i.e. the rights statement referenced by a unique ID should remain persistent).

Technical details on the use of this optional package are as follows:

The <rightsManifest> package contains a list of the rights statements disseminated by the repository. The schema provides for this by allowing one or more <rights> tags, each of which must have a unique ID and must contain a rights statement either:
- in-line: The rights statement may be contained in XML syntax within the <rights> element. The elements of the rights statement must be defined in a namespace distinct from the OAI elements and may be subject to validation to external schema. Otherwise, the nature of the rights statement is undefined by this schema.
- by-reference: The rights statement may be referenced via a URL contained within the <rights> element. There are no restrictions on the nature of the resource referenced by this URL. However to facilitate machine processing, the recommended format for referenced rights statements is XML.
Records disseminated by the repository may contain a <rights> package of the by-reference form, that references one of the <rights> tags in the Identify response returned by the respective repository. This URL must be formatted as baseURL?verb=Identify#rightsStatementID, where:
- baseURL?verb=Identify is an OAI-PMH Identify request to the repository that disseminated the record containing the URL reference.
- rightsStatementID is the unique ID of the <rights> element in the <description> part of the Identify response, where the ID is specified in the rightsStatementID attribute of the <rights> tag.

The schema for this optional <rightsManifest> package is:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="http://www.openarchives.org/OAI/2.0/Rights/Repository" 
  xmlns:xlink="http://www.w3.org/1999/xlink" 
  xmlns:xs="http://www.w3.org/2001/XMLSchema" 
  xmlns:recRights="http://www.openarchives.org/OAI/2.0/Rights/Record" 
  xmlns="http://www.openarchives.org/OAI/2.0/Rights/Repository" 
  elementFormDefault="qualified" attributeFormDefault="unqualified">
  <xs:import namespace="http://www.openarchives.org/OAI/2.0/Rights/Record" 
    schemaLocation="http://www.openarchives.org/OAI/2.0/RecordRightsPackage.xsd"/>
  <xs:element name="rightsManifest">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="rights" type="rightsStatementType" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:complexType name="rightsStatementType">
    <xs:complexContent>
      <xs:extension base="recRights:rightsStatementType">
        <xs:attribute name="rightsStatementID" type="xs:ID" use="required"/>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>
</xs:schema>

This Schema is available at http://www.openarchives.org/OAI/2.0/DescriptionRightsPackage.xsd

The following example shows the use of this <rights> container within a <description> element.

<Description>
  <rightsManifest xmlnsi="http://www.openarchives.org/OAI/2.0/Rights/Repository" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:recRights="http://www.openarchives.org/OAI/2.0/Rights/Record"  
    xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/Rights/Repository 
      http://www.openarchives.org/OAI/2.0/DescriptionRightsPackage.xsd">
    <rights rightsStatementID="all">
      <recRights:rightsDefinition>
        <rdf:RDF xmlns="http://web.resource.org/cc/" 
          xmlns:dc="http://purl.org/dc/elements/1.1/" 
          xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
          <Work rdf:about="">
            <dc:type rdf:resource="http://purl.org/dc/dcmitype/Text"/>
            <license rdf:resource="http://creativecommons.org/licenses/by/2.0/"/>
          </Work>
          <License rdf:about="http://creativecommons.org/licenses/by/2.0/">
            <permits rdf:resource="http://web.resource.org/cc/Reproduction"/>
            <permits rdf:resource="http://web.resource.org/cc/Distribution"/>
            <requires rdf:resource="http://web.resource.org/cc/Notice"/>
            <requires rdf:resource="http://web.resource.org/cc/Attribution"/>
            <permits rdf:resource="http://web.resource.org/cc/DerivativeWorks"/>
          </License>
        </rdf:RDF>
      </recRights:rightsDefinition>
    </rights>
    <rights rightsStatementID="noncommercial">
      <recRights:rightsDefinition>
        <rdf:RDF xmlns="http://web.resource.org/cc/" 
          xmlns:dc="http://purl.org/dc/elements/1.1/" 
          xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
          <Work rdf:about="">
            <dc:type rdf:resource="http://purl.org/dc/dcmitype/Text"/>
            <license rdf:resource="http://creativecommons.org/licenses/by-nc/2.0/"/>
          </Work>
          <License rdf:about="http://creativecommons.org/licenses/by-nc/2.0/">
            <permits rdf:resource="http://web.resource.org/cc/Reproduction"/>
            <permits rdf:resource="http://web.resource.org/cc/Distribution"/>
            <requires rdf:resource="http://web.resource.org/cc/Notice"/>
            <requires rdf:resource="http://web.resource.org/cc/Attribution"/>
            <prohibits rdf:resource="http://web.resource.org/cc/CommercialUse"/>
            <permits rdf:resource="http://web.resource.org/cc/DerivativeWorks"/>
          </License>
        </rdf:RDF>
      </recRights:rightsDefinition>
    </rights>
    <rights rightsStatementID="nomods">
      <recRights:rightsReference ref="http://creativecommons.org/licenses/by-nd/2.0/"/>
    </rights>
  </rightsManifest>
</Description>

The following example demonstrates the form of an <about> container associated with a record disseminated by a repository that returns the <description> container shown above. The example assumes a baseURL for this repository of http://an.oa.org.

<about>
  <rights xmlns="http://www.openarchives.org/OAI/2.0/Rights/Record"  
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/Rights/Record
  http://www.openarchives.org/OAI/2.0/RecordRightsPackage.xsd">
    <rightsReference ref="http://an.oa.org?verb=Identify#noncommerical"/>
  </rights>
</about>

This <about> container references the <rights> labeled "noncommercial" in the <Description> container of the Identify response from the repository, and associates that rights statement with the contents of the <metadata> element of the record in which the <about> container is packaged.

5. Responsibilities of clients harvesting metadata with rights statements

The mechanisms described in this document are not intended to provide any level of enforcement of rights statements. Nevertheless, consumers of metadata containing this rights statements should act in good faith and abide by the conditions as stated. Actions in response to a failure of a client to follow a condition are out of the scope of this specification.

Acknowledgements

Support for the development of the OAI-PMH and for other Open Archives Initiative activities comes from the Digital Library Federation, the Coalition for Networked Information, and from the National Science Foundation through Grant No. IIS-9817416. Individuals who have played a significant role in the development of OAI-PMH version 2.0 are acknowledged in the protocol document.

Document History

2004-05-27: First draft of this document..
2004-06-02: Second draft with substantive changes