{"id":1792,"date":"2014-12-22T00:00:00","date_gmt":"2014-12-21T23:00:00","guid":{"rendered":"https:\/\/wwwneu.strehle.de\/tim\/weblog\/archives\/2014\/12\/22\/1754\/"},"modified":"2025-11-07T14:02:01","modified_gmt":"2025-11-07T13:02:01","slug":"1754","status":"publish","type":"post","link":"https:\/\/www.strehle.de\/tim\/weblog\/archives\/2014\/12\/22\/1754\/","title":{"rendered":"Hunting for well-known Semantic Web vocabularies and terms"},"content":{"rendered":"\n

As a Semantic Web \/ Linked Data<\/a> newbie, I\u2019m struggling with finding the right URIs for properties and values.<\/p>\n\n\n\n

Say I have a screenshot as an PNG image file.<\/p>\n\n\n\n

If I were to describe it in the Atom feed<\/a> format, I\u2019d make an \u201centry\u201d for it, write the file size into the \u201clink\/@length\u201d attribute, the \u201cimage\/png\u201d MIME type into the \u201clink\/@type\u201d attribute, and a short textual description into \u201ccontent\u201d (with \u201c@xml:lang\u201d set to \u201cen\u201d). Very easy for me to produce, and the semantics would be clear to everyone reading the Atom standard.<\/p>\n\n\n\n

Now I want to take part in the \u201cSemWeb\u201d and describe my screenshot in RDFa<\/a> instead. (In order to allow highly extensible data exchange between different vendors\u2019 Digital Asset Management systems, for example.) But suddenly life is hard: For each property (\u201cfile size\u201d, \u201cMIME type\u201d, \u201cdescription\u201d) and some values (\u201ctype: file\u201d, \u201cMIME type: image\/png\u201d, \u201clanguage: English\u201d) I\u2019ve got to provide a URL (or URI).<\/p>\n\n\n\n

I could make up URLs on my own domain \u2013 how about http:\/\/strehle.de\/schema\/fileSize ? But that would be missing the point and prevent interoperability. How to Publish Linked Data on the Web<\/a> puts it like this: \u201cA set of well-known vocabularies has evolved in the Semantic Web community. Please check whether your data can be represented using terms from these vocabularies before defining any new terms.\u201d<\/p>\n\n\n\n

The previous link lists about a dozen of vocabularies. There\u2019s a longer list in the State of the LOD Cloud<\/a> report. And a W3C VocabularyMarket<\/a> page. These all seem a bit dated and incomplete: None of them link to schema.org<\/a>, one of the more important vocabularies in my opinion. (Browsing Semantic Web resources in general is no fun, you run into lots of outdated stuff and broken links.) And I haven\u2019t found a good search engine that covers these vocabularies: I don\u2019t want to browse twenty different sites to find out which one defines a \u201cfile size\u201d term.<\/p>\n\n\n\n

I\u2019m pretty sure the Semantic Web pros know where to look, and how to do this best. Please drop me a line if you can help \ud83d\ude42<\/p>\n\n\n\n

Update:<\/em> The answer is the Linked Open Vocabularies<\/a> site. Check it out!<\/p>\n\n\n\n

For the record, here\u2019s what I found so far for my screenshot example:<\/p>\n\n\n\n

\u201cfile size\u201d: https:\/\/schema.org\/contentSize<\/a><\/p>\n\n\n\n

\u201cMIME type: http:\/\/en.wikipedia.org\/wiki\/Internet_media_type<\/a> or http:\/\/www.wikidata.org\/wiki\/Q1667978<\/a><\/p>\n\n\n\n

\u201cdescription\u201d: http:\/\/purl.org\/dc\/terms\/description<\/a> or https:\/\/schema.org\/text<\/a><\/p>\n\n\n\n

\u201ctype: file\u201d: http:\/\/en.wikipedia.org\/wiki\/Computer_file<\/a> or http:\/\/www.wikidata.org\/wiki\/Q82753<\/a>, or more specific: http:\/\/schema.org\/MediaObject<\/a> or http:\/\/schema.org\/ImageObject<\/a> or even http:\/\/schema.org\/screenshot<\/a><\/p>\n\n\n\n

\u201cMIME type: image\/png\u201d: http:\/\/purl.org\/NET\/mediatypes\/image\/png<\/a> or http:\/\/www.iana.org\/assignments\/media-types\/image\/png<\/a><\/p>\n\n\n\n

\u201clanguage: English\u201d: http:\/\/en.wikipedia.org\/wiki\/English_language<\/a> or http:\/\/www.lingvoj.org\/languages\/tag-en.html<\/a> or https:\/\/www.wikidata.org\/wiki\/Q1860<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

As a Semantic Web \/ Linked Data newbie, I\u2019m struggling with finding the right URIs for properties and values. Say I have a screenshot as an PNG image file. If I were to describe it in the Atom feed format, I\u2019d make an \u201centry\u201d for it, write the file size into the \u201clink\/@length\u201d attribute, the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[1],"tags":[],"class_list":["post-1792","post","type-post","status-publish","format-standard","hentry","category-weblog"],"share_on_mastodon":{"url":"","error":""},"_links":{"self":[{"href":"https:\/\/www.strehle.de\/tim\/wp-json\/wp\/v2\/posts\/1792","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.strehle.de\/tim\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.strehle.de\/tim\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.strehle.de\/tim\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.strehle.de\/tim\/wp-json\/wp\/v2\/comments?post=1792"}],"version-history":[{"count":3,"href":"https:\/\/www.strehle.de\/tim\/wp-json\/wp\/v2\/posts\/1792\/revisions"}],"predecessor-version":[{"id":2256,"href":"https:\/\/www.strehle.de\/tim\/wp-json\/wp\/v2\/posts\/1792\/revisions\/2256"}],"wp:attachment":[{"href":"https:\/\/www.strehle.de\/tim\/wp-json\/wp\/v2\/media?parent=1792"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.strehle.de\/tim\/wp-json\/wp\/v2\/categories?post=1792"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.strehle.de\/tim\/wp-json\/wp\/v2\/tags?post=1792"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}