3. Target vocabulary
The Target vocabulary namespace is http://semweb.mmlab.be/ns/rml-target#
and it's prefix is rmlt.
The Target vocabulary consists of a single class: rmlt:LogicalTarget
to describe how a knowledge graph must be exported after generation.
3.1 Defining Targets
A Target is any target to where RDF triples are exported to.
A Target (rmlt:LogicalTarget) contains the following properties:
- The target (
rmlt:target) locates the output target. It is a URI [RFC3986] or Literal [RDF-Concepts] that represents the target's location. External vocabulary such as DCAT, VoID, SD is allowed here. Eachrmlt:LogicalTargetMUST have onermlt:targetproperty. The target MAY be a Literal containing the path the file to where the knowledge graph is exported to, this is allowed to stay backwards compatibility with existing data access descriptions. - The serialization format (
rmlt:serialization) MAY specify the serialization format for exporting a knowledge graph. The serialization format is described using the W3C formats namespace. By default, the serialization format is N-Quads [N-Quads]. - The compression algorithm (
rmlt:compression) MAY describe the compression algorithm to apply when exporting a knowledge graph. The compression format is specified through the comp namespace. By default, no compression is applied.
The Target definition requires only the target (rmlt:target) to be specified,
all other properties are optional.
| Property | Domain | Range |
|---|---|---|
rmlt:target |
rmlt:LogicalTarget |
URI or Literal |
rmlt:serialization |
rmlt:LogicalTarget |
formats:Format |
rmlt:compression |
rmlt:LogicalTarget |
comp:Compression |
3.2 Examples
The following example show a Target of an RDF dump in Turtle [Turtle] format with GZip compression:
<#VoIDDump> a rmlt:LogicalTarget;
rmlt:target [ a void:Dataset;
void:dataDump <file:///data/dump.ttl>;
];
rmlt:serialization formats:Turtle;
rmlt:compression comp:gzip;
.
The following example shows a Target of a [SPARQL]
endpoint with SPARQL UPDATE:
<#SPARQLEndpoint> a rmlt:LogicalTarget;
rmlt:target [ a sd:Service;
sd:endpoint <http://example.com/sparql-update>;
sd:supportedLanguage sd:SPARQL11Update ;
];
.
The following example shows a Target of a DCAT dataset in N-Quads format with Zip compression:
<#DCATDump> a rmlt:LogicalTarget;
rmlt:target [ a dcat:Dataset;
dcat:distribution [ a dcat:Distribution;
dcat:accessURL <http://example.org/dcat-access-url>;
];
];
rmlt:serialization formats:N-Quads;
rmlt:compression comp:zip;
.