Repository Revision Metadata

Each Dydra repository possesses two kinds of metadata: intrinsic and historic. Information about revisions belongs to the historic data which is made available primarily in the form of a timemap. This section describes metadata which Dydra maintains on repository revisions, how to retrieve this information, and how to use it to perform revision-specific queries.

The intrinsic metadata, which includes things like the repository name or its description, the supported access methods, protocols, and locations is the primary subject the repository service description. In combination with a revision specification, however, the service description carries also historic metadata in the form of the constituent graphs contingent on the revision.

A simple repository history would appear as follows.

Metadata - timemap

A repository timemap enumerates the revisions as subjects of type <urn:dydra:Revision> with <http://www.mementoweb.org/terms/tb/start> and, optionally, <http://www.mementoweb.org/terms/tb/end> properties to indicate their respective temporal bounds.

$ curl -s -L -H "Accept: application/link-format" "http://dydra.com/statistics/dydra.com" \
  | rapper --quiet -i ntriples -o turtle /dev/stdin -
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

<http://dydra.com/statistics/dydra.com>
    <http://purl.org/dc/terms/created> "2013-04-21T10:10:51Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> ;
    <http://purl.org/dc/terms/modified> "2013-04-21T10:10:51Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> ;
    <http://www.mementoweb.org/terms/tb/covers> [
        <http://www.mementoweb.org/terms/tb/start> "2013-04-21T03:40:26Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> ;
        a <http://www.mementoweb.org/terms/tb/Period>
    ] ;
    <http://www.mementoweb.org/terms/tb/timeGateFor> <http://dydra.com/statistics/dydra.com> ;
    <http://www.openarchives.org/ore/terms/describes> [
        <http://purl.org/dc/elements/1.1/title> "Memento Time Bundle for 'http://dydra.com/statistics/dydra.com'" ;
        <http://www.openarchives.org/ore/terms/aggregates> <http://dydra.com/statistics/dydra.com>,
                                                           <urn:dydra:revision:dcb8778f-e823-d84e-9d3e-dce6f563d0d7> ;
        a <http://www.mementoweb.org/terms/tb/TimeBundle>,
          <http://www.openarchives.org/ore/terms/Aggregation>
    ] ;
    a <http://www.mementoweb.org/terms/tb/OriginalResource>,
      <http://www.mementoweb.org/terms/tb/TimeGate>,
      <http://www.mementoweb.org/terms/tb/TimeMap>,
      <http://www.openarchives.org/ore/terms/ResourceMap> .

<urn:dydra:revision:dcb8778f-e823-d84e-9d3e-dce6f563d0d7>
    <http://www.mementoweb.org/terms/tb/mementoFor> <http://dydra.com/statistics/dydra.com> ;
    <http://www.mementoweb.org/terms/tb/validOver> [
        <http://www.mementoweb.org/terms/tb/start> "2013-04-21T03:40:26Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> ;
        a <http://www.mementoweb.org/terms/tb/Period>
    ] ;
    a <http://www.mementoweb.org/terms/tb/Memento>,
      <urn:dydra:Revision> .

Metadata - service-description

A repository service description enumerates the graphs and statement counts for the respective revision, in addition to intrinsic metadata. When no revision is specified, the document describes the latest revision.

$ curl -s -L "http://dydra.com/statistics/dydra.com" \
  | rapper --quiet -i ntriples -o turtle /dev/stdin -
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

<http://dydra.com/statistics/dydra.com>
    a <http://www.w3.org/ns/sparql-service-description#Service> ;
    <http://www.w3.org/ns/sparql-service-description#availableGraphs> [
        a <http://www.w3.org/ns/sparql-service-description#GraphCollection> ;
        <http://www.w3.org/ns/sparql-service-description#namedGraph>
          <http://dydra.com/jhacker/149-describe-1>,
          <http://dydra.com/jhacker/726-base>,
          <http://dydra.com/jhacker/726-provenance>,
          <http://dydra.com/jhacker/aggregates-agg-avg-01>,
          # ...
          <urn:dydra:all>, <urn:dydra:default>, <urn:dydra:named>
    ] ;
    <http://www.w3.org/ns/sparql-service-description#defaultDataset> [
        a <http://www.w3.org/ns/sparql-service-description#Dataset> ;
        <http://www.w3.org/ns/sparql-service-description#defaultGraph> <urn:dydra:default>
    ] ;
    <http://www.w3.org/ns/sparql-service-description#endpoint> <http://dydra.com/statistics/dydra.com> ;
    <http://www.w3.org/ns/sparql-service-description#inputFormat>
      <http://www.w3.org/ns/formats/N-Triples>,
      <http://www.w3.org/ns/formats/RDF_XML>,
      <http://www.w3.org/ns/formats/Turtle> ;
    <http://www.w3.org/ns/sparql-service-description#resultFormat>
      <http://www.w3.org/ns/formats/RDF_XML>,
      <http://www.w3.org/ns/formats/SPARQL_Results_CSV>,
      <http://www.w3.org/ns/formats/SPARQL_Results_JSON> ;
    <http://www.w3.org/ns/sparql-service-description#supportedLanguage>
      <http://www.w3.org/ns/sparql-service-description#SPARQL10Query>,
      <http://www.w3.org/ns/sparql-service-description#SPARQL11Query>,
      <http://www.w3.org/ns/sparql-service-description#SPARQL11Update> .

<http://dydra.com/jhacker/149-describe-1>
    <http://rdfs.org/ns/void#triples> 118 ;
    a <http://www.w3.org/ns/sparql-service-description#NamedGraph> ;
    <http://www.w3.org/ns/sparql-service-description#name> <http://dydra.com/jhacker/149-describe-1> .

<http://dydra.com/jhacker/726-base>
    <http://rdfs.org/ns/void#triples> 272 ;
    a <http://www.w3.org/ns/sparql-service-description#NamedGraph> ;
    <http://www.w3.org/ns/sparql-service-description#name> <http://dydra.com/jhacker/726-base> .

<http://dydra.com/jhacker/726-provenance>
    <http://rdfs.org/ns/void#triples> 578 ;
    a <http://www.w3.org/ns/sparql-service-description#NamedGraph> ;
    <http://www.w3.org/ns/sparql-service-description#name> <http://dydra.com/jhacker/726-provenance> .

<http://dydra.com/jhacker/aggregates-agg-avg-01>
    <http://rdfs.org/ns/void#triples> 119 ;
    a <http://www.w3.org/ns/sparql-service-description#NamedGraph> ;
    <http://www.w3.org/ns/sparql-service-description#name> <http://dydra.com/jhacker/aggregates-agg-avg-01> .

# ...

<urn:dydra:all>
    a <http://www.w3.org/ns/sparql-service-description#Graph> ;
    <http://www.w3.org/ns/sparql-service-description#name> <urn:dydra:all> .

<urn:dydra:default>
    <http://rdfs.org/ns/void#triples> 0 ;
    a <http://www.w3.org/ns/sparql-service-description#Graph> ;
    <http://www.w3.org/ns/sparql-service-description#name> <urn:dydra:default> .

<urn:dydra:named>
    a <http://www.w3.org/ns/sparql-service-description#Graph> ;
    <http://www.w3.org/ns/sparql-service-description#name> <urn:dydra:named> .

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