Linked open data

What is Linked Open Data?

Linkedata.org states, "Linked Data is about using the Web to connect related data that wasn't previously linked, or using the Web to lower the barriers to linking data currently linked using other methods. More specifically, Wikipedia defines Linked Data as 'a term used to describe a recommended best practice for exposing, sharing, and connecting pieces of data, information, and knowledge on the Semantic Web using URIs and RDF.'"

LAWDI starts with an even simpler definition. Linked Open Data encompasses any creation of or reference to stable URIs for scholarly resources related to the Ancient World. Examples of stable URIs include those created by the Pleiades project for geographic entities (e.g. http://pleiades.stoa.org/places/658381 for Antioch ) and by the American Numismatic Society's for its coins (e.g.http://numismatics.org/collection/1984.146.586). And note that the ANS record links to the Pleiades record. A list of other projects publishing clean and stable URI is available on the page Very clean URIs. By bringing together people with a serious interest in both the creation and re-use of such URIs, LAWDI will forward the goal of a richly linked internet that encourages the discovery of high-quality information.

How do I learn what it is all about?

One of the best overall introductions to the topic is Tom Heath and Christian Bizer's Linked Data: Evolving the Web into a Global Data Space, available in print, HTML, or pdf. Once you have read that, or if you find that introduction inadequate, here are other starting points:

• Linked Data, an excellent starting place for various resources
• Wikipedia's entry about linked data
• Linked open vocabularies, a visual map of vocabularies
• Video on linked data by Manu Sporny
• W3 Consortium, introduction to the topic
• Tim Berners-Lee, video introduction
• Tim Berners-Lee, classic (2006) introduction
• Linked Open Data for Cultural Heritage (Sunoikisis Digital Classics 2018 online seminar)
• Hugh Cayless, Sustaining Linked Ancient World Data (2019)

I've heard of RDF, but what is it?

RDF is short for 'Resource Description Framework'. RDF is a way of placing information on the internet so that it is readable and usable by automatic processors. An example, is the Pleiades URI for Antioch used above: http://pleiades.stoa.org/places/658381 . If you append '/rdf' to that address (http://pleiades.stoa.org/places/658381/rdf), you'll get the text given in the box below. Look closely and it's not very hard to read. '<skos:altLabel>Theoupolis</skos:altLabel>' is just a standardized way of indicating that the site Antioch also had the name Theoupolis.

See here for other examples.

<?xml version="1.0" encoding="utf-8"?>
<rdf:RDF
  xmlns:foaf="http://xmlns.com/foaf/0.1/"
  xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
  xmlns:geo="http://www.w3.org/2003/01/geo/wgs84_pos#"
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:spatial="http://geovocab.org/spatial#"
  xmlns:skos="http://www.w3.org/2004/02/skos/core#"
>
 <spatial:Feature rdf:about="http://pleiades.stoa.org/places/658381#this">
    <geo:lat rdf:datatype="http://www.w3.org/2001/XMLSchema#float">36.202097</geo:lat>
    <foaf:primaryTopicOf rdf:resource="http://pleiades.stoa.org/places/658381"/>
    <rdfs:comment>An ancient place, cited: BAtlas 67 C4 Antiochia/Theoupolis</rdfs:comment>
    <skos:altLabel>Antiochia</skos:altLabel>
    <skos:altLabel>Theoupolis</skos:altLabel>
    <skos:altLabel>Iopolis</skos:altLabel>
    <geo:long rdf:datatype="http://www.w3.org/2001/XMLSchema#float">36.15818</geo:long>
    <rdfs:label>Antiochia/Theoupolis</rdfs:label>
  </spatial:Feature>
</rdf:RDF>