ORE Specification - Abstract Data Model

17 October 2008

This version:
http://www.openarchives.org/ore/1.0/datamodel
Latest version:
http://www.openarchives.org/ore/datamodel
Previous version:
http://www.openarchives.org/ore/0.9/datamodel
Editors (OAI Executive)
Carl Lagoze, Cornell University Information Science
Herbert Van de Sompel, Los Alamos National Laboratory
Editors (ORE Technical Committee)
Pete Johnston, Eduserv Foundation
Michael Nelson, Old Dominion University
Robert Sanderson, University of Liverpool
Simeon Warner, Cornell University Information Science

Abstract

Open Archives Initiative Object Reuse and Exchange (OAI-ORE) defines standards for the description and exchange of aggregations of Web resources. This document describes the abstract data model that is the foundation for these standards. This model is conformant with the Architecture of the World Wide Web [Web Architecture] and leverages concepts from the Semantic Web including RDF descriptions [RDF Concepts] and Linked Data [Linked Data Tutorial].

This specification is one of several documents comprising the OAI-ORE specifications and user guides. The intended audience for this document is implementers that have an understanding of Semantic Web Concepts. Readers that want a high-level understanding of the motivation for ORE, and of the solution it provides should read the ORE Primer.


Table of Contents

1. Introduction
    1.1 Notational Conventions
    1.2 Namespaces
2. Foundations
3. Data Model Entities
    3.1 Aggregation
    3.2 Aggregated Resource
    3.3 Resource Map
    3.4 Proxy
4. RDF Graph of a Resource Map - Basics
    4.1 Relationship between a Resource Map and an Aggregation
    4.2 Metadata about the Resource Map and Aggregation
    4.3 Aggregated Resources and the Aggregation Graph
    4.4 Relationships between the Aggregation and Similar Resources
    4.5 Relationships to other Resources and Types
5. RDF Graph of a Resource Map - Advanced
    5.1 Asserting that an Aggregated Resource is a constituent of another Aggregation
    5.2 Nesting Aggregations
    5.3 Proxies for Aggregated Resources
        5.3.1. Proxies: Relationships among Aggregated Resources
        5.3.2. Proxies: Externally asserted relationships to Aggregated Resources
        5.3.3. Proxies: Lineage of an Aggregated Resource
6. Structural Constraints on a Resource Map
7. References

Appendices

A. Acknowledgements
B. Change Log


1. Introduction

The Architecture of the World Wide Web [Web Architecture] uses the term Resource to refer to any item of interest. Some web content, such as a stand-alone HTML document, is contained within one Resource. But frequently a logical unit of web information is actually an aggregation of Resources. Examples of these aggregations are:

These aggregations exhibit the following characteristics:

A mechanism to associate identities with these aggregations and describe them in a machine-readable manner would make them visible to Web agents including browsers and crawlers. These machine-readable descriptions could then be the basis of user interfaces, allowing users to navigate and manipulate the aggregations. Some example applications and contexts where "aggregation-awareness" might be useful include:

This document describes the Open Archives Initiative Object Reuse and Exchange (OAI-ORE) data model for the description and exchange of aggregations of Web resources, named Aggregations. OAI-ORE introduces the notion of Resource Maps that describe an Aggregation. A Resource Map describes an Aggregation: it asserts the finite set of constituent resources (the Aggregated Resources) of the Aggregation, and it can express types and relationships pertaining to the Aggregation and its Aggregated Resources. This data model conforms to the concepts defined in the Architecture of the World Wide Web [Web Architecture].

The ORE Model can be implemented in a variety of serialization formats. The details of these formats are described in companion ORE documents. The nature of a particular serialization format and its respective expressiveness may affect the details of the mapping from the model to the implementation. This mapping is described in detail in each serialization specification.

1.1 Notational Conventions

The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [IETF RFC 2119].

The use of fonts is as follows:

1.2 Namespaces

This specification uses the following namespaces and prefixes to indicate those namespaces:

Prefix Namespace URI Description
dc http://purl.org/dc/elements/1.1/ Dublin Core elements
dcterms http://purl.org/dc/terms/ Dublin Core terms
foaf http://xmlns.com/foaf/0.1/ Friend of a Friend
ore http://www.openarchives.org/ore/terms/ ORE vocabulary terms
owl http://www.w3.org/2002/07/owl# OWL vocabulary terms
rdf http://www.w3.org/1999/02/22-rdf-syntax-ns# RDF vocabulary terms
rdfs http://www.w3.org/2000/01/rdf-schema# RDF Schema

2. Foundations

The ORE Data Model builds on the following foundation technologies and architectures.

Readers unfamiliar with these technologies are encouraged to refer to reference documents for each. A brief introduction to the relevant aspects of these technologies is also available in the ORE Primer.

3. Data Model Entities

The ORE Abstract Data Model includes the entities that are described in the remainder of this section.

3.1 Aggregation

An Aggregation is a Resource of type ore:Aggregation that is a set of other Resources. The type ore:Aggregation is associated with a Resource via an assertion by at least one Resource Map. The association between a Resource Map and an Aggregation is described in a section 4.1.

This specification uses URI-A to denote URIs that identify Aggregations. Because URI-A identifies the Aggregation, it SHOULD be used as the target of links referring to the set of Resources as a logical unit. Examples of such links are citation, review, annotation, and the like.

Because a URI-A identifies the Aggregation, it SHOULD NOT be a URI used for another purpose, such as the URI of a specific manifestation of some content — for example, the PDF of some scholarly paper — or the URI of a human-readable "splash page", which really identifies only that page and not the Aggregation as a whole.

A URI-A MUST be a protocol-based URI. However, an Aggregation is a conceptual construct, and thus it does not have a Representation. In contrast, a Resource Map that asserts the Aggregation does have a Representation in which that assertion is made available to clients and agents. The Cool URIs for the Semantic Web guidlines are adopted to support discovery of the HTTP URI of the asserting Resource Map given the HTTP URI of an Aggregation. Details about the mechanisms of access are described in ORE User Guide - HTTP Implementation.

3.2 Aggregated Resource

An Aggregated Resource is a Resource that is a constituent of an Aggregation due to an assertion in a Resource Map that describes the containing Aggregation.The manner in which these assertions are made is described in section 4.3.

This specification uses URI-AR to denote URIs that identify Aggregated Resources. A URI-AR MUST be a protocol-based URI.

3.3 Resource Map (ReM)

A Resource Map (ReM) is a Resource, with type ore:ResourceMap, with information content consisting of assertions that:

The nature of these assertions are described in section 4.1.

Each Resource Map MUST be identified by a single protocol-based URI, which MUST be distinct from the Aggregation identified by the Resource Map. This specification uses URI-R to denote URIs that identify Resource Maps. There MAY be multiple Resource Maps for a single Aggregation. Each Resource Map MUST have a distinct URI (rather than forming multiple Representations from a single URI-R). A deference of a URI-R results in a serialization which the assertions described above can be extracted as a set of triples that when combined form an RDF Graph that MUST conform to a well-defined structure.

Multiple Resource Maps MAY contain assertions about the same Aggregation, identified in each with a single URI, URI-A. These Resource Maps fall into two classes:

Unless specifically noted, the remainder of this specification will describe only authoritative Resource Maps. The qualifier "authoritative" will only be used for appropriate emphasis.

3.4 Proxy

A Proxy is a Resource, with type ore:Proxy, that indicates an Aggregated Resource in the context of a specific Aggregation. The type ore:Proxy is associated with a Resource via an assertion in a Resource Map that describes the Aggregation that is the context of the Proxy.The URI of a Proxy, indicated by URI-P throughout this specification, then can be used in assertions specific to the Aggregated Resource in the context of that aggregation. This contrasts with the URI-AR of the Aggregated Resource, which has no special meaning relative to the Aggregation. The use of Proxies, which are OPTIONAL, is described in section 5.3.

A Proxy URI (URI-P) MUST be unique to both an Aggregation (URI-A) and to a particular Aggregated Resource (URI-AR) of that Aggregation. Using the terminology described above this means that a URI-P asserted in an authoritative Resource Map for one URI-A MUST NOT be asserted in Resource Maps that describe another URI-A. When implemented using HTTP, Proxy URIs SHOULD conform to certain requirements.

4. RDF Graph of a Resource Map - Basics

A Resource Map asserts a set of RDF triples expressing information about an Aggregation, its constituent Aggregated Resources, metadata about the Aggregation and Resource Map, and other Relationships. The RDF Graph that is manifested by the triples asserted by a Resource Map MUST conform to a number of restrictions. The graph MUST be connected, with its structure defined as follows (and expanded upon in the numbered section accompanying each bullet):

The remainder of this section explains the components of this graph in a step-by-step progression. The constraints on the graph are summarized in a table later in this document.

Later sections describe how to extend this RDF Graph to assert relationships between Aggregations and the use of Proxies to establish Aggregation-specific URIs for Aggregated Resources.

4.1 Relationship between a Resource Map and an Aggregation

A Resource Map MUST include one triple with an ore:describes predicate. The subject of this triple MUST be the URI-R of the Resource Map. The object is the URI-A of the Aggregation described by the Resource Map. The URI-A that is the object of this triple MUST NOT be the same as URI-R. A Resource Map MUST NOT include more than one triple with the ore:describes predicate.

The ore:describes relationship asserts that the Resource denoted by the subject is a resource of type ore:ResourceMap and the Resource denoted by the object is a resource of type ore:Aggregation. Therefore, the explicit inclusion in the Resource Map of triples asserting these types is OPTIONAL.

The figure below illustrates the RDF Graph expressing the relationship between a Resource Map and an Aggregation. The triples producing the graph are included below the graph. The table to the right of the triples shows the URIs used to identify the Resources and relationships. The syntax of the URIs in the triples table are illustrative only and the reader SHOULD NOT infer metadata about the identified resource from the form of the URIs. The ORE User Guide - HTTP Implementation describes implementation details on suggested syntax for URIs used in ORE.

Relationship between a Resource Map and an Aggregation

As described earlier, multiple Resource Maps MAY assert an ore:describes relationship with the same URI-A as the object of the triple. In the case where there are multiple Resource Maps, each Resource Map SHOULD assert a triple with the ore:isDescribedBy predicate (the inverse of ore:describes) expressing a relationship with each other authoritative Resource Map. These triples make alternate serializations of a Resource Map visible to clients.

The figure below illustrates the existence of multiple Resource Maps and the use of the ore:isDescribedBy predicate. Note that the illustrated assertions are expressed by ReM-1 in the figure.

Multiple Resource Maps

4.2 Metadata about the Resource Map and Aggregation

A Resource Map MUST express minimal metadata properties about the Resource Map. Those metadata properties are:

A Resource Map MAY include additional metadata properties about the Resource Map. Examples of additional metadata properties are:

A Resource Map MAY assert metadata properties about the Aggregation. These metadata properties MAY be defined by a variety of vocabularies. A common metadata property is the identity of the authoring authority (human, organization, or agent) of the Aggregation, using the dcterms:creator predicate.

The figure below shows an RDF Graph expressed by a Resource Map that includes metadata properties about Resource Map and Aggregation. Note that aspects of the graph already described are grayed-out to emphasize the concepts introduced by the figure. This convention will be used for the remainder of this document along with other simplifications to make the figures easier to read.

Resource Map metadata figure

4.3 Aggregated Resources and the Aggregation Graph

A Resource Map MAY include one or more triples with the ore:aggregates predicate. Each asserts that the object of the predicate identified by URI-AR is an Aggregated Resource of the subject identified by URI-A. A URI-AR MUST NOT be the same as the URI-A of the Aggregation that is the subject of the ore:aggregates predicate.

The ore:aggregates relationship defines that the Resource denoted by the subject is a Resource of type ore:Aggregation. Therefore, the explicit inclusion in the Resource Map of a triple asserting the type is OPTIONAL.

A Resource Map MAY include one or more triples with the ore:isAggregatedBy predicate to assert that an Aggregated Resources is a constituent of other Aggregations.

The figure below shows the RDF Graph with the addition of triples with the ore:aggregates predicate. This subgraph of the RDF Graph, rooted in the Aggregation with one or more ore:aggregates relationships to Aggregated Resources, is known as the Aggregation Graph.As described earlier, all authoritative Resource Maps describing the same Aggregation MUST assert the same Aggregation Graph.

Aggregation with ore:aggregates figure

For a Resource Map http://example.org/ReM-1, the Aggregation Graph is defined by the following SPARQL query [SPARQL].

PREFIX ore: <http://www.openarchives.org/ore/terms/>
CONSTRUCT   { ?a ore:aggregates ?ar1 . }
WHERE       { <http://example.org/ReM-1> ore:describes ?a .
              ?a ore:aggregates ?ar1 . }

4.4 Relationships between the Aggregation and Similar Resources

A Resource Map MAY include one or more triples, with URI-A as the subject, which assert that the Aggregation is a Resource with content that is similar to another Resource. The predicate MAY be either rdfs:seeAlso or its sub-property ore:similarTo. The predicate actually used depends on the strength of the assertion of similarity.

The ore:similarTo relationship asserts that the Aggregation has similar intellectual content to the Resource identified by the object of the triple. An example of the use of ore:similarTo in the scholarly communication context is the relationship between an Aggregation and a Resource with non-protocol-based URI like a Digital Object Identifier [DOI] or an info URI [INFO].

An example of the use of the weaker rdfs:seeAlso in a Resource Map is the relationship between two Aggregations that have an ore:similarTo relationship to the same DOI.

The use of ore:similarTo and rdfs:seeAlso predicates in a Resource Map is shown in the figure below.

Aggregation associated with other resource using ore:similarTo

4.5 Relationships to other Resources and Types

A Resource Map MAY include additional triples that assert properties about the Resource Map, Aggregation, Aggregated Resources, or other related Resources or Literals. The RDF graph produced by the addition of these triples MUST be connected. Formally that means that all nodes in the graph MUST be reachable via a traversal that begins at the node denoting the Resource Map and follows the edges corresponding to the predicates expressed in the triples.

Some appropriate uses for additional relationships are:

The scope of these additional assertions corresponds to the global manner in which RDF statements are interpreted. That is, the meaning of these additional triples are not constrained or altered by their "assertion context" in a Resource Map. Each assertion is essentially independent, and therefore a triple with subject URI-AR is a statement about that Resource without reference to its existence in the respective Aggregation. Assertions about Resources contextualized by the Aggregation via the use of Proxies are described in section 5.3.1.

The figure below shows the RDF Graph with the addition of triples expressing type semantics and other relationships to the Aggregation Graph.

External relationships figure

5. RDF Graph of a Resource Map - Advanced

This specification has thus far included the mechanisms for describing an individual Aggregation. This section describes mechanisms by which one Resource Map MAY assert relationships between Aggregated Resources and other Resource Maps or Aggregations.

5.1 Asserting that an Aggregated Resource is a constituent of another Aggregation

A Resource Map MAY include one or more triples with the ore:isAggregatedBy predicate to assert that an Aggregated Resources is a constituent of other Aggregations.

A use case is flickr, in which it is possible for a picture to be a member of multiple sets. The Resource Map describing a set might include information about other set memberships of its constituent pictures. The figure below shows three Aggregations, A-1, A-2, and A-3, corresponding to the three sets in flickr. All include some image, AR-3, as an Aggregated Resource. The Resource Map ReM-3, which describes the flickr set A-3, includes triples with the predicate ore:isAggregatedBy, asserting that AR-3 is constituent of the sets denoted by the Aggregations A-1 and A-2.

Use of isAggregatedBy figure

5.2 Nesting Aggregations

As stated earlier, any Resource can be an Aggregated Resource in some Aggregation. Because an Aggregation is itself a Resource, it can be an Aggregated Resource in some other Aggregation. The result is then recursive nesting of Aggregations. Note that this nesting MUST be expressed in multiple Resource Maps, since one Resource Map MUST describe only one Aggregation.

A Resource Map that asserts another Aggregation as an Aggregated Resource MAY assert an ore:isDescribedBy relationship between this Aggregated Resource and a Resource Map describing the other Aggregation. This informs clients of the Resource Map of the nesting.

Note that this use of the ore:isDescribedBy predicate has the same semantics as described earlier. The predicate asserts that the subject of the triple, which is an Aggregation, is described by the object of the triple, which is a Resource Map.

An example of a nested Aggregation is a journal consisting of multiple issues, each of which is an Aggregation of multiple articles, each of which may be an Aggregation in its own right. The figure below illustrates nested Aggregations, omitting some details of previous figures (e.g. metadata, typing). Aggregation A-1, described by ReM-1, has constituents AR-1, AR-2 and AR-3, which are themselves Aggregations. Each of these "aggregated Aggregations" is described by a corresponding Resource Map (ReM-2, ReM-3, and ReM-4) which describes the Aggregated Resources and other aspects of these Aggregations. The sub-graphs associated with these other Resource Maps are intentionally grayed out to emphasize the fact that the triples relevant to this example are exclusive to ReM-1.

Nested Aggregations figure

5.3.Proxies for Aggregated Resources

This specification has thus far used the URI-AR of an Aggregated Resource as the subject or object of triples. As described earlier, a URI-AR is not specific to the Aggregation — an individual URI-AR MAY be asserted within multiple Aggregations and MAY be used independent of any Aggregation. Thus, the use of URI-AR as the subject or object of triples does not imply any association with one Aggregation, or even with any Aggregation at all.

In some cases it is useful to assert relationships to Aggregated Resources in a manner specific to the Aggregation context. These relationships may be among Aggregated Resources or between Aggregated Resources and Resources external to the Aggregation. A URI distinct from the URI-AR is then necessary.

This section describes the notion of a Proxy, which is a Resource that "stands for" an Aggregated Resource in a manner that is specific to one Aggregation. The URI-P of this Proxy is then available for use in triples where the intended semantics is a relationship specific to the Aggregated Resource in the context of the respective Aggregation. Note that the assertion of Proxies is OPTIONAL and unnecessary if context-specific assertions are not needed.

The URI-P of the Proxy MUST be unique to the Aggregation. A Resource Map MUST assert two triples to associate the Proxy with the Aggregation and Aggregated Resource.

A Resource Map MUST assert only one of each of these pairs of triples for each Proxy. All authoritative Resource Maps for an Aggregation MUST assert the same Proxies.

The remainder of this section describes use cases for Proxies and how to express them in the Resource Map

5.3.1 Proxies: Relationships among Aggregated Resources

An example of the use of Proxies for relationships among Aggregated Resources is the assertion of sequencing between Aggregated Resources, expressing an ordered list where AR-1 follows AR-2 which follows AR-3. Without any sequencing information, the order of Aggregated Resources can not be inferred — they form an unordered set. It would not be legitimate for the Resource Map to express this sequencing by asserting a triple of the sort <AR-1> <hasNext> <AR-2>, since this fact is only true in the context of the specific Aggregation, and is not a "global" fact. As noted earlier, in RDF the meaning of triples are not constrained or altered by their "assertion context" in a Resource Map. Each assertion is essentially independent, and therefore a triple with subject or object URI-AR is a statement about that Aggregated Resource without reference to its existence in the respective Aggregation. Therefore, a relationship such as the previously mentioned "sequence" must be expressed in terms of Proxies that denote Aggregated Resources contextualized by a specific Aggregation

The following figure illustrates how to express this Aggregation-specific sequencing via the definition of proxies and assertion of related triples in a Resource Map. The hypothetical predicate xyz:hasNext used in the figure indicates a sequencing relationship between the two Aggregated Resources. The Resource Map ReM-1 defines two Proxies P-1 and P-2. It also asserts triples with the ore:proxyFor and ore:proxyIn predicates that associate the Proxies with the respective Aggregated Resource and with the Aggregation. These Proxies are then the subject and object of the xyz:hasNext predicate, asserting the sequencing relationship in the context of the Aggregation.

Proxy node figure

5.3.2. Proxies: Externally asserted relationships to Aggregated Resources

A Proxy can be the subject or object of triples asserted elsewhere, with semantics that the relationship asserted by the triples are specific to the Aggregated Resources contextualized by the Aggregation.

The figure below illustrates an example of this use of a Proxy. In the example, the Aggregation A-1 may be a collection of best scholarly papers found on the web about some selected topic. AR-1 is one of these selected papers. A citation to that paper, asserted by the triple <URI-2> <xyz:cites> <AR-1>, carries no semantics about the selection of the paper in the "best papers" collection, because the URI AR-1 is simply the identity of the paper. However, the triple <URI-1> <xyz:cites> <P-1>, where P-1 is asserted by the Resource Map to be the Proxy for AR-1, is semantically a citation to that paper as a constituent of the "best papers" collection.

The assertion of Proxies is OPTIONAL. This example demonstrates that it MAY make sense for an agency creating Resource Maps to assert these Proxies to provide appropriate link targets for outside clients.

Context link figure

5.3.3. Proxies: Lineage of an Aggregated Resource

As described earlier, the ore:isAggregatedBy predicate asserts that an Aggregated Resource in one Aggregation is also an Aggregated Resource in another Aggregation. In fact, one Aggregated Resource MAY be in multiple Aggregations, and therefore it MAY be the subject of multiple ore:isAggregatedBy triples. In applications such as scholarly communication there is a need for a stronger relationship indicating lineage, which indicates that an Aggregated Resource originated or was sourced from another Aggregation. Lineage or provenance is one basis of integrity in scholarly communication.

A Resource Map MAY assert triples with the predicate ore:lineage to express this notion. The subject of ore:lineage MUST be a Proxy specific to the Aggregation and the object MUST be a Proxy specific to another Aggregation. Both the subject and object Proxy Resource MUST be proxies for the same Aggregated Resource. In other words, the Resource Map for subject Proxy MUST contain a triple <P-1> <ore:proxyFor> <AR-1> and the Resource Map for object Proxy MUST contain a triple <P-2> <ore:proxyFor> <AR-1> where AR-1 is the same in both triples. One Proxy MUST NOT be the subject of more than one ore:lineage relationships expressed in a Resource Map.

The following figure illustrates the use of ore:lineage. Aggregation A-1 is an eScience result aggregating, with other Resources not shown, some data set, AR-1. Aggregation A-2 includes the same data set. Both Resource Maps establish proxies for that Aggregated Resource, P-1 in A-1 and P-2 in A-2, creating Aggregation-specific URIs for the data set. ReM-2 also asserts the triple <P-2> <ore-lineage> <P-1> to express the origin or provenance of the data set in Aggregation A-1.

Lineage figure

6.Structural Constraints on a Resource Map

The following table summarizes the constraints on the structure of an RDF Graph that serves as a Resource Map by specifying the minimum and maximum expected occurrences of Triples of varying forms.

The convention used in the table is that

Subject Predicate Object
Occurs (Min, Max)
Note
ReM-1 ore:describes A-1
(1, 1)
Relationship between Resource Map and Aggregation (4.1)
A-1 ore:isDescribedBy ReM-i
(1, *)
Relationship between Resource Map and Aggregation (4.1)
ReM-1 rdf:type ore:ResourceMap
(0, 1)
Typing of Resource Map (4.1)
ReM-1 dcterms:creator Agent
(1, *)
Metadata about Resource Map (Required) (4.2)
ReM-1 dcterms:modified literal
(1, 1)
Metadata about Resource Map (Required) (4.2)
ReM-1 URI-Property literal or URI-Object
(0, *)
Metadata about Resource Map (Optional) (4.2)
URI-Subject URI-Property ReM-1
(0, *)
Metadata about Resource Map (Optional) (4.2)
Agent foaf:name literal
(0, 1)
Metadata about Creator of Resource Map or Aggregation (Optional) (4.2)
Agent foaf:mbox URI-Object
(0, 1)
Metadata about Creator of Resource Map or Aggregation (Optional) (4.2)
A-1 ore:aggregates AR-j
(0, *)
Relationship between Aggregation and aggregated Resource (4.3)
A-1 rdf:type ore:Aggregation
(0, 1)
Typing of Aggregation (4.3)
A-1 ore:similarTo URI-Object
(0, *)
Relationships between the Aggregation and similar resources (4.4)
A-1 rdfs:seeAlso URI-Object
(0, *)
Relationships between the Aggregation and similar resources (4.4)
A-1 URI-Property literal or URI-Object
(0, *)
Other properties of the Aggregation (4.2)/Relationships of Aggregation to Other Resources (4.5)
URI-Subject URI-Property A-1
(0, *)
Relationships of Aggregation to Other Resources (4.5)
AR-j URI-Property literal or URI-Object
(0, *)
Relationships of aggregated Resource to Other Resources (4.5)
URI-Subject URI-Property AR-j
(0, *)
Relationships of aggregated Resource to Other Resources (4.5)
URI-Subject URI-Property URI-Object
(0,*)

Additional metadata in the Resource Map (4.5)

  • URI-Subject must be directly or transitively connected to AR-j, A-1, or ReM-1 in the RDF Graph defined by the triples in the Resource Map.
  • URI-Property must not be ore:aggregates, ore:describes
AR-j ore:isAggregatedBy A-k
(0, *)
Aggregated Resource as constituent of another Aggregation (5.1)
AR-j ore:isDescribedBy ReM-i
(0, *)
Nesting Aggregations (5.2)
P-j ore:proxyFor AR-j
(0, 1)
Relationship between Proxy and aggregated Resource (5.3)
P-j ore:proxyIn A-1
(0, 1)
Relationship between Proxy and Aggregation (5.3)
P-j URI-Property P-m
(0, *)
Relationships between Proxies (5.3.1)
URI-Subject URI-Property P-j
(0, *)
Proxy as target of Relationships (5.3.2)
P-j URI-Property literal or URI-Object
(0, *)
Proxy as subject of Relationships (5.3.2)
P-j ore:lineage P-m
(0, *)
Lineage Relationship between Proxies (5.3.3)

 

The UML diagram below shows the relationships between the key entities in the ORE model.

UML diagram of key entities in ORE

7. References

[Cool URIs]
Cool URIs for the Semantic Web Leo Sauermann, Richard Cyganiak, Danny Ayers, Max Völkel, 2008-03-31. Available at http://www.w3.org/TR/2008/NOTE-cooluris-20080331/ and latest version at http://www.w3.org/TR/cooluris/ .
[Compound Object]
Compound Information Object Archive Prototype Demonstration, H. Van de Sompel, 2007.
[Dereferencing]
Dereferencing HTTP URIs, R. Lewis, Draft Tag Finding 31 May 2007
[DC RDF]
Expressing Dublin Core metadata using the Resource Description Framework (RDF), Mikael Nilsson, Andy Powell, Pete Johnston, Ambjorn Naeve. DCMI Working Draft, 2006-05-30
[DC Terms]
DCMI Metadata Terms, DCMI Usage Board, 2006-12-18.
[DOI]
The DOI System, The International DOI Foundation.
[INFO]
The "info" URI Scheme for Information Assets with Identifiers in Public Namespaces, H. Van de Sompel, et al., RFC 4552, IETF, 2006.
[Linked Data Tutorial]
How to Publish Linked Data on the Web, Chris Bizer, Richard Cyganiak, Tom Heath, 2007-07-27. Available at http://www4.wiwiss.fu-berlin.de/bizer/pub/LinkedDataTutorial/20070727/ . Latest version available at http://www4.wiwiss.fu-berlin.de/bizer/pub/LinkedDataTutorial/ .
[OWL]
OWL Web Ontology Language Guide, Michael Smith, Chris Welty, Deborah McGuiness, Editors, W3C Recommendation 10 February 2004, Latest Version http://www.w3.org/TR/owl-guide/.
[RDF Concepts]
Resource Description Framework (RDF): Concepts and Abstract Syntax,, Graham Klyne and Jeremy J. Carroll, Editors, W3C Recommendation, 10 February 2004, http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/ . Latest version available at http://www.w3.org/TR/rdf-concepts/ .
[RDF Semantics]
RDF Semantics, Patrick Hayes and Brian McBride, Editors, W3C Recommendation 10 February 2004, http://www.w3.org/TR/2004/REC-rdf-mt-20040210/
[RDFS]
RDF Vocabulary Description Language 1.0: RDF Schema, Dan Brickley and R.V. Guha, Editors. W3C Recommendation, 10 February 2004, http://www.w3.org/TR/2004/REC-rdf-schema-20040210/ .
Latest version available at http://www.w3.org/TR/rdf-schema/ .
[RFC2119]
IETF RFC 2119: Key words for use in RFCs to Indicate Requirement Levels, S. Bradner, March 1997. Available at http://www.ietf.org/rfc/rfc2119.txt.
[RFC2616]
IETF RFC 2616: Hypertext Transfer Protocol - HTTP/1.1, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P. Leach, T. Berners-Lee, June 1999. Available at http://www.ietf.org/rfc/rfc2616.txt .
[Lynch CTWatch]
The Shape of the Scientific Article in The Developing Cyberinfrastructure, C. Lynch, CTWatch Quarterly, August 2007.
[SCOPE]
SCOPE - A Scientific Compound Object Publishing and Editing System. K. Cheung, J. Hunger, A. Lashtabeg, J. Drennan, Proceedings of the 3rd International Digital Curation Conference, 2007.
[SPARQL]
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A. Acknowledgements

This document is the work of the Open Archives Initiative. Funding for Open Archives Initiative Object Reuse and Exchange is provided by the Andrew W. Mellon Foundation, Microsoft, and the National Science Foundation.  Additional support is provided by the Coalition for Networked Information.

This document is based on meetings of the OAI-ORE Technical Committee (ORE-TC), with participation from the OAI-ORE Liaison Group (ORE-LG).  Members of the ORE-TC are: Chris Bizer (Freie Universität Berlin), Les Carr (University of Southampton), Tim DiLauro (Johns Hopkins University), Leigh Dodds (Ingenta), David Fulker (UCAR), Tony Hammond (Nature Publishing Group), Pete Johnston (Eduserv Foundation), Richard Jones (Imperial College), Peter Murray (OhioLINK), Michael Nelson (Old Dominion University), Ray Plante (NCSA and National Virtual Observatory), Rob Sanderson (University of Liverpool), Simeon Warner (Cornell University), and Jeff Young (OCLC).  Members of ORE-LG are: Leonardo Candela (DRIVER), Tim Cole (DLF Aquifer and UIUC Library), Julie Allinson (JISC), Jane Hunter (DEST), Savas Parastatidis  (Microsoft), Sandy Payette (Fedora Commons), Thomas Place (DARE and University of Tilburg), Andy Powell (DCMI), and Robert Tansley (Google, Inc. and DSpace)

We also acknowledge comments from the OAI-ORE Advisory Committee (ORE-AC).

B. Change Log

Date Editor Description
2008-10-17 lagoze public 1.0 release
2008-06-02 lagoze public beta 0.9 release
2008-03-28 lagoze public alpha 0.3 release
2008-02-27 lagoze public alpha 0.2 release
2007-12-10 lagoze public alpha 0.1 release
2007-10-15 lagoze alpha release to ORE-TC

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