9.1.2 Finding manifest files

The initial metadata file(s) are loaded into the system using rdf_attach_library/1.

rdf_attach_library(+FileOrDirectory)

Load meta-data on RDF repositories from FileOrDirectory. If the argument is a directory, this directory is processed recursively and each for each directory, a file named void.ttl, Manifest.ttl or Manifest.rdf is 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.

<wn-basic>
        a void:Dataset ;
        dcterms:title "Basic WordNet" ;
        ...

rdf_list_library

List the available resources in the library. Currently only lists resources that have a dcterms:title property. See section 9.2 for an example.

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:

rdf_list_library(+Id)

Same as rdf_list_library(Id,[]).

rdf_list_library(+Id, +Options)

Lists the resources that will be loaded if Id is handed to rdf_load_library/2. See rdf_attach_library/1 for how ontology identifiers are generated. In addition it checks the existence of each resource to help debugging library dependencies. Before doing its work, rdf_list_library/2 reloads manifests that have changed since they were loaded the last time. For HTTP resources it uses the HEAD method to verify existence and last modification time of resources.

rdf_load_library(+Id, +Options)

Load the given library. First rdf_load_library/2 will establish what resources need to be loaded and whether all resources exist. Than it will load the resources.