RDF has a standard XML syntax which has nice merging properties but isn't so nice for authors and doesn't integrate well with DTDs, XML Schemas, and the like. There will always be various alternative formats that can be used to encode information and publish it as structured data on the Web. In order to make this information available to RDF systems, some sort of pre-processing is necessary. This page collects general approaches and concrete mappings.
Approaches
GRDDL is a technique for processing XML/XHTML dialects (especially microformats) as custom RDF syntaxes by having each document point, directly or indirectly, to a transformation to an RDF graph. GRDDL accomodates a wide variety of dialects (at the expense of asking consumers to execute potentially untrusted code). In theory, GRDDL can be combined with arbitrary transformation mechanisms, for now it's mostly based on XSLTs.
RDFa and eRDF are designs for serializing RDF in HTML. They allow a single parser (or GRDDL transformation!) to work for data from any domain and provide a direct relationship between the RDF data and the HTML document structure, which can improve human interaction with enriched Web content (e.g. for copy-and-paste of information).
Custom parsers can be used to convert a particular serialization to RDF. Dialect-specific parsers can be valuable for non-XML/tagsoup formats, or in systems where XSLT is not an efficient approach.
HTML-based Dialects
Dialect |
Domain |
Schema |
Mapping |
Status |
Notes |
Bibliographic Metadata |
Dublin Core |
@@cite request to make it official |
upgradeable to eRDF+GRDDL |
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generic |
RDF |
by IanDavis |
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Geo (lat/long) |
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HTML links/link@rel |
#html, DC |
maintained by DannyAyers |
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Calendars and Events |
maintained by DanConnolly since Dec 2002 |
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Contact Information |
maintained by Walsh, Halpin, and Suda since Nov 2006; used in xtech schedule |
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Software project description |
hDoap |
maintained by DannyAyers |
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Opinions, Ratings and Reviews |
See RDF Review |
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generic |
RDF |
by SeanPalmer |
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meta/link@rel + generic |
various |
maintained by MasahideKanzaki |
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generic |
RDF |
by Fabien Gandon, collaborating with the GRDDL and RDFa WGs |
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Licenses |
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Tags, Keywords, Categories |
? |
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Syndication |
RSS |
html2rss.xsl |
in production on the W3C homepage |
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Social Graph |
maintained(?) by DanConnolly |
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Syndication |
RSS |
html2rss.xsl |
in production on the W3C homepage |
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Social Graph |
Maintained by MartinMcEvoy |
See also hFoaF |
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Audio Syndication |
hAudio as RSS1 |
Maintained by MartinMcEvoy |
See also hAudio to RSS |
Non-HTML based dialects
Dialect |
Domain |
Schema |
Mapping |
Status |
RSS |
Syndication |
RSS 1.0 |
usable |
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Atom |
Syndication |
Atom/OWL |
incomplete* |
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Atom |
Syndication |
RSS 1.0 |
usable** |
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OPML |
Feedlists |
FOAF/RSS 1.0 |
usable** |
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OPML |
Feedlists |
FOAF/RSS 1.0/SKOS |
usable** |
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Metalink |
File sharing |
metalink |
(under revision 2007-10) |
maintained by DannyAyers |
APML |
Attention Profiling |
apml |
- |
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web service description |
SAWSDL |
profile, SAWSDL_GRDDL.xsl |
under development at INRIA (contact Mohamed Bennis and Fabien Gandon) |
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topic maps |
XTM |
profile, XTM_GRDDL.xsl |
under development at INRIA (contact Priscille Durville and Fabien Gandon) |
* there are several other XSLTs around, discussion is in-progress on which is best for Atom/GRDDL
** OPML tends to be used ad hoc, it's only minimally specified and data in the wild varies wildly, hence it's impossible to give definitive mappings
migrating from MicroModels, grddlmicromodels, EmbeddingRDFinHTML, CustomRdfDialects/GrddableMicroformats, etc.