Notes on MIME types

The following MIME types are usable at one point or another when interacting with Quaestor:

application/rdf+xml

This indicates that the content (upload or response) is formatted in the standard RDF/XML serialisation.

application/sparql-query

When annotating a SPARQL response, this produces a response in XML, using the SPARQL response XML schema.

text/turtle

Turtle is a well-established but still experimental text syntax for RDF. It's very closely related to Notation3, but without some of that syntax's non-RDF extensions. The MIME type is not yet registered, but text/turtle is being requested; Turtle has also been served with the MIME type application/x-turtle.

application/xml

This is the MIME type which should accompany a POSTed SPARQL query. See the specification for more details. The application/sparql-query should generally be preferred, as being more specific.

text/csv (SELECT query responses only)

Comma-separated-value output, conforming to RFC 4180. The Content-Type of the response is text/csv;header=present, indicating that the first line of the response consists of 'column headings', consisting of the substitution variables in the input query. These are not guaranteed to be in the same order as they were listed in the input query.

text/plain

This MIME type means various different things in different contexts.

Annotating a SPARQL response, this indicates that the content is in a human-readable format, intended to look roughly like the usual result of a SQL query. It is not intended to be machine-parseable.

The MIME type of the N-triple format is also text/plain; however N-triple format is intended only for the RDF test cases, and is not expected to be useful otherwise (that's the party line, though in fact N-triple format can be quite useful when you need something that's trivial to parse, or when you want, say, to check how base-URIs have been resolved). When retrieving an ontology (using the GET HTTP method) or uploading one (using PUT), you can use text/plain to indicate N-triples (but don't tell W3C).

text/rdf+n3

This indicates that the content (upload or response) is formatted in Notation-3. The application/n3 MIME type is recognised but deprecated (see W3 discussion), since its IANA registration was never completed; text/rdf+n3 is the preferred MIME type for Notation3.

text/tab-separated-values (SELECT query responses only)

Tab-separated-value output, conforming to the (rather informal) specification at IANA. The first line will include a row of 'column headings' as above.