Data Catalog Resources
Back in November 2014 OMB’s Project Open Data adopted DCAT (then at version 1) as the reporting schema for data.gov. To the DCATv1 schema OMB added a number of US Government specific terms. This combined schema is called DCAT-US Schema v1.1. You can find it at https://resources.data.gov/resources/dcat-us/ .
DCAT is a project of the WC3’s Data Exchange Working Group. DCATv2 is the current W3C “recommendation” and DCATv3 is now in draft. You can find the draft here: https://www.w3.org/TR/vocab-dcat-3/ DCAT is an RDF vocabulary that can be expressed in JSON, XML, and other languages. A favorite of the W3C crowd is “Turtle” which is compact and easy to author. There should be software to easily and automatically convert RDF statements between these various representations.
DCAT links to other standards. Somewhat confusingly, DCAT uses both FOAF and VCARD to describe individuals, so we reference both of them before. FOAF ("Friend of a Friend") was original developed to describe relationships in a social network. VCARD was developed to add "business cards" to email messages. FOAF is a decidedly XML-style schema, while VCARD is based on blocks of ASCII lines, like many of the Internet standards from the 1980s and 1990s.
I suggest reading these sources in this order:
Core Concepts
- RDF 1.1 Turtle, an easy-to-use notation for RDF triples. See also the Turtle (syntax) description on Wikipedia.
- Research Description Framework, an overview of RDF
- Web Ontology Language
- DCAT-US Schema v1.1, the schema that is used to report information to data.gov
- DCATv3 - Data Catalog Vocabulary (DCAT), how we represent catalog information
- Dublin Core Metadata Initiative, and especially the DCMI Metadata Terms
- Shapes Constraint Language
FOAF
- FOAF (ontology) on Wikipedia
- FOAF Vocabulary Specification 0.99, the actual vocab used for FOAF. See an example of FOAF in XML from the O'Reilly XML Hacks book. Also see the Introduction to FOAF on the xml.com website.
A well-developed FOAT focabulary is on dbpedia.org:
VCARD
Some of the items in DCAT are described with vCards.
