This module allows loading data into the semantic web library directly from an HTTP server. The following example loads the RDF core data into the RDF database.

:- use_module(library(semweb/rdf_db)).
:- use_module(library(semweb/rdf_http_plugin)).

    ...,
    rdf_load('http://www.w3.org/1999/02/22-rdf-syntax-ns')

 rdf_extra_headers(-RequestHeaders:list(compound), +Options:list) is det[private]

Send extra headers with the request. Note that, although we also process RDF embedded in HTML, we do not explicitly ask for it. Doing so causes some (e.g., http://w3.org/2004/02/skos/core to reply with the HTML description rather than the RDF).

When given, option format(+atom) is used in order to prioritize the corresponding RDF content types.

 rdf_db:rdf_open_hook(+Scheme, +URL, +HaveModified, -Stream, -Cleanup, -Modified, -Format, +Options) is semidet[multifile]

Load hook implementation for HTTP(S) URLs.

Arguments:

HaveModified	- is bound to a timestamp (number) if we already have a copy and that copy was modified at HaveModified.
Modified	- is bound to unknown, not_modified or a timestamp.

 ssl_verify(+SSL, +ProblemCert, +AllCerts, +FirstCert, +Error)

Currently we accept all certificates.

 modified_since_header(+LastModified, -ExtraHeaders) is det[private]

Add an If-modified-since if we have a version with the given time-stamp.

 open_envelope(+ContentType, +SourceURL, +Stream0, -Stream, ?Format) is semidet[private]

Open possible envelope formats.

 rdf_accept_header_value(?Format:rdf_format, -AcceptValue:atom) is det[private]

 rdf_content_type(?MediaType:atom, ?QualityValue:between(0.0,1.0), ?Format:rdf_format) is nondet[multifile]

Quality values are intended to be used in accordance with RFC 2616. Quality values are determined based on the following criteria:

Label	Criterion	Value
A	Supported RDF parser	0.43
B	RDF-specific content type	0.33
C	Official content type	0.23

For example, text/turtle has quality value 0.99 because it is an official content type that is RDF-specific and that has a parser in Semweb.

This intentionally allows the user to add another content type with a higher Q-value (i.e., >0.99).

Deduce the RDF encoding from the mime-type. This predicate is defined as multifile such that the user can associate additional content types to RDF formats.

See also

- Discussion http://richard.cyganiak.de/blog/2008/03/what-is-your-rdf-browsers-accept-header/

- N-Quadruples http://www.w3.org/ns/formats/N-Quads

- N-Triples http://www.w3.org/ns/formats/N-Triples

- N3 http://www.w3.org/ns/formats/N3

- RDFa http://www.w3.org/ns/formats/RDFa

- TriG http://www.w3.org/ns/formats/TriG

- Turtle http://www.w3.org/ns/formats/Turtle

- XML/RDF http://www.w3.org/ns/formats/RDF_XML

bug

- The turtle parser only parses a subset of n3. (The N3 format is treated as if it were Turtle.)