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ocre:ocre_-_participation

Participating in OCRE

In the spring of 2013, we took a new approach in establishing links from RIC types in OCRE to physical coins and hoards which reference those types. While these instructions are specific to OCRE, they can be applied to any coins or hoards which link to coin types defined by Nomisma IDs (e.g., Crawford's Roman Republican Coinage corpus).

The new system uses a Fuseki triplestore and SPARQL endpoint for accepting RDF which associates resources describing coins and hoards to coin type URIs. OCRE, in addition to other Numishare-based coin type projects, use SPARQL to read data from the triplestore to show thumbnail images in search results and record pages, as well as process findspots into KML and JSON for rendering in maps. From a developer's standpoint, the new system is significantly easier to maintain in the long term. SPARQL contains mathematical functions for returning spans or average weights for a given query, removing the need to process these measurements stored in Solr. OCRE only needs to be re-indexed into Solr when new findspots are added, as the query-based Maps page still depends on Solr for speed. Maps in OCRE record pages are generated from SPARQL results.

RDF Data Models

Coins and hoards represented by RDF have some similarities, but also have some differences. The Dublin Core terms “Title,” “Publisher,” and “Identifier” are used in both models. Both include an <nm:type_series_item> with an rdf:resource pointing to the URI which defines a coin type. Physical coins likely only point to one type URI, but hoards may contain many. The examples shown below are in RDF/XML, but Fuseki can accept RDF in any common format.

Physical Coins

An example for a physical coin from the University of Virginia Art Museum Numismatic Collection is shown below:

<rdf:RDF xmlns:dcterms="http://purl.org/dc/terms/"        
         xmlns:owl="http://www.w3.org/2002/07/owl#"
         xmlns:skos="http://www.w3.org/2004/02/skos/core#"
         xmlns:nm="http://nomisma.org/id/"
         xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
   <nm:coin rdf:about="http://coins.lib.virginia.edu/id/1997.7.2">
      <dcterms:title xml:lang="en">Aureus of Hadrian, Rome, A.D. 134-138. 1997.7.2.</dcterms:title>
      <dcterms:identifier>1997.7.2</dcterms:identifier>
      <dcterms:publisher>University of Virginia Library</dcterms:publisher>
      <nm:collection>The University of Virginia Art Museum</nm:collection>
      <nm:type_series_item rdf:resource="http://numismatics.org/ocre/id/ric.2.hdn.271b"/>
      <nm:axis rdf:datatype="xs:integer">6</nm:axis>
      <nm:diameter rdf:datatype="xs:decimal">18.0</nm:diameter>
      <nm:weight rdf:datatype="xs:decimal">7.34</nm:weight>
      <nm:obverseThumbnail rdf:resource="http://coins.lib.virginia.edu/images/coins/thumb/n1997_7_2_obv.jpg"/>
      <nm:obverseReference rdf:resource="http://coins.lib.virginia.edu/images/coins/screen/n1997_7_2_obv.jpg"/>
      <nm:reverseThumbnail rdf:resource="http://coins.lib.virginia.edu/images/coins/thumb/n1997_7_2_rev.jpg"/>
      <nm:reverseReference rdf:resource="http://coins.lib.virginia.edu/images/coins/screen/n1997_7_2_rev.jpg"/>
   </nm:coin>
</rdf:RDF>

The title, publisher, and identifier are required, as is the nm:numismatic_term, and nm:type_series_item. nm:collection is recommended, especially in cases where the publisher and collection are different. A coin must point to “http://nomisma.org/id/coin” in the nm:numismatic_term.

There are several fields which are particular to physical objects (and not hoards): nm:axis, nm:diameter, nm:weight, and obverse/reverse thumbnail and references images (to be added as necessary). None of these fields is required, though the measurements can be used for quantitative analyses. The measurements should be associated with an rdf:database–xs:decimal for weights and diameters, xs:integer for axis (unless the source data uses fractional numbers for axes).

Although none of the coins currently linked to OCRE have attested findspots, findspots can expressed with nm:findspot in two ways: 1) with an rdf:resource pointing to a URI on the web (for example, a Geonames.org URI) or 2) or W3C defined geoRDF (see below).

<nm:findspot>
      <rdf:Description rdf:about="http://www.geonames.org/670093/">
        <geo:lat>37.689444</geo:lat>
        <geo:long>26.943056</geo:long>
      </rdf:Description>
</nm:findspot>

Hoards

An example of an RDF resource for a hoard from CHRR is shown below:

<rdf:RDF xmlns:dcterms="http://purl.org/dc/terms/"        
         xmlns:owl="http://www.w3.org/2002/07/owl#"
         xmlns:skos="http://www.w3.org/2004/02/skos/core#"
         xmlns:nm="http://nomisma.org/id/"
         xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
   <nm:hoard rdf:about="http://numismatics.org/chrr/id/AGG">
      <dcterms:title xml:lang="en">Aggius (Sardinia; AGG)</dcterms:title>
      <dcterms:identifier>AGG</dcterms:identifier>
      <dcterms:publisher>Kris Lockyear</dcterms:publisher>
      <nm:numismatic_term rdf:resource="http://nomisma.org/id/hoard"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-206.1"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-250.1"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-279.1"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-342.5b"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-352.1a"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-366.4"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-383.1"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-431.1"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-442.1a"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-458.1"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-463.1b"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-494.23"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-544.14"/>
      <nm:type_series_item rdf:resource="http://nomisma.org/id/rrc-544.18"/>
      <nm:type_series_item rdf:resource="http://numismatics.org/ocre/id/ric.1(2).aug.37a"/>
      <nm:type_series_item rdf:resource="http://numismatics.org/ocre/id/ric.1(2).aug.207"/>
      <nm:closing_date rdf:datatype="xs:gYear">0004</nm:closing_date>
      <nm:findspot>
         <rdf:Description rdf:about="http://www.geonames.org/3183443/">
            <geo:lat>40.93037</geo:lat>
            <geo:long>9.06592</geo:long>
         </rdf:Description>
      </nm:findspot>
   </nm:hoard>
</rdf:RDF>

Like physical coins, the dcterms:publisher, dcterms:title, and dcterms:identifier are required, as well is the nm:numismatic_term, defined by the rdf:resource, “http://nomisma.org/id/hoard

Hoards may contain many nm:type_series_items. They may even include other typologies expressed by the Nomisma ontology (for example, “nm:denomination”→“http://nomisma.org/id/tetradrachm”) so that SPARQL queries may made based on those ontologies. Keep in mind that SPARQL queries can access these individual typological attributes through the coin type resource itself. Only those hoards which link to coin types defined in OCRE (like http://numismatics.org/ocre/id/ric.1(2).aug.37a) will be available in OCRE.

The nm:closing_date is optional, but if it is a year, it should conform to the rdf:datatype, xs:gYear (four digit number, padded with zeroes. Negative numbers represent B.C. dates).

The nm:findspot may be expressed, as with physical coins above, with an rdf:resource or the geoRDF ontology. The nm:findspot is not explicitly required, but without it, the hoard will not appear in maps in OCRE. However, if a findspot is absent, and the closing_date is present, the hoard will still appear in the timeline in the OCRE coin type record page.

Contributing the RDF to OCRE

Please email Ethan Gruber to coordinate testing and ingesting your RDF into Fuseki. Once the RDF passes consistency checks, coins and hoards described in the RDF will become available in OCRE immediately upon POSTing into Fuseki.

ocre/ocre_-_participation.txt · Last modified: 2013/07/15 16:04 by egruber