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|The Manifest file|
A manifest file is an RDF file, often in
format, that provides meta-data about RDF resources. Often, a manifest
will describe RDF files in the current directory, but it can also
describe RDF resources at arbitrary URL locations. The RDF schema for
RDF library meta-data can be found in
namespace for the RDF library format is defined as
and abbreviated as
The schema defines three root classes: lib:Namespace, lib:Ontology and lib:Virtual, which we describe below.
, the basename of each loaded file is appended to the given source. Defaults to the URL the RDF is loaded from.
wn-fullas virtual resources. The lib:Virtual resource is used as a second rdf:type:
<wn-basic> a lib:Ontology ; a lib:Virtual ; ...
@prefix lib: <http://www.swi-prolog.org/rdf/library/> . @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> . [ a lib:Namespace ; lib:mnemonic "rdfs" ; lib:namespace rdfs: ] .
The VoID aims at resolving the same problem as the Manifest files described here. In addition, the VANN vocabulary provides the information about preferred namepaces prefixes. The RDF library manager can deal with VoID files. The following relations apply:
Linksetare similar to
lib:Ontology, but a VoID resource is always Virtual. I.e., the VoID URI itself never refers to an RDF document.
owl:importsand its lib specializations are replaced by
void:subset(referring to another VoID dataset) and
void:dataDump(referring to a concrete document).
lib:Cloudnode, which have no equivalent in VoID.
vann:preferredNamespaceUrias alternatives to its proprietary way for defining prefixes. The domain of these predicates is unclear. The library recognises them regardless of the domain. Note that the range of
vann:preferredNamespaceUriis a literal. A disadvantage of that is that the Turtle prefix declaration cannot be reused.
Currently, the RDF metadata is not stored in the RDF database. It is processed by low-level primitives that do not perform RDFS reasoning. In particular, this means that rdfs:supPropertyOf and rdfs:subClassOf cannot be used to specialise the RDF meta vocabulary.
The initial metadata file(s) are loaded into the system using rdf_attach_library/1.
Manifest.rdfis loaded (in this order of preference).
Declared namespaces are added to the rdf-db namespace list.
Encountered ontologies are added to a private database of
rdf_list_library.pl. Each ontology is given an
identifier, derived from the basename of the URL without the
extension. This, using the declaration below, the identifier of the
declared ontology is
<wn-basic> a void:Dataset ; dcterms:title "Basic WordNet" ; ...
It is possible for the initial set of manifests to refer to RDF files that are not covered by a manifest. If such a reference is encountered while loading or listing a library, the library manager will look for a manifest file in the directory holding the referenced RDF file and load this manifest. If a manifest is found that covers the referenced file, the directives found in the manifest will be followed. Otherwise the RDF resource is simply loaded using the current defaults.
Further exploration of the library is achieved using rdf_list_library/1 or rdf_list_library/2: