This tutorial introduces the sc-sparql Semantic Containers image. Refer to the Tutorial-Overview for other aspects.
Download the Semantic Container SPARQL base image from Dockerhub with the following command:
$ docker pull semcon/sc-sparqlTo start a SPARQL container the configuration requires RML for mapping the available data to RDF. In the following example the seismic data in seismic.json is mapped with the following RML:
@prefix scs: <http://w3id.org/semcon/ns/seismic#> .
@prefix rr: <http://www.w3.org/ns/r2rml#> .
@prefix rml: <http://semweb.mmlab.be/ns/rml#> .
@prefix ql: <http://semweb.mmlab.be/ns/ql#> .
@prefix carml: <http://carml.taxonic.com/carml/> .
@prefix dcterm: <http://purl.org/dc/terms/> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix wgs: <http://www.w3.org/2003/01/geo/wgs84_pos#> .
@prefix geo: <http://www.opengis.net/ont/geosparql#> .
@prefix func: <http://semantics.id/ns/function#> .
@prefix param: <http://semantics.id/ns/parameter#> .
@prefix fnml: <http://semweb.mmlab.be/ns/fnml#> .
@prefix fno: <http://semweb.datasciencelab.be/ns/function#> .
<#SeismicMapping>
rml:logicalSource [
rml:source [
a carml:Stream;
];
rml:referenceFormulation ql:JSONPath;
rml:iterator "$.provision.content.[*]" ;
];
rr:subjectMap [
rr:template "http://w3id.org/semcon/seismic/{sourceId}" ;
];
rr:predicateObjectMap [
rr:predicate rdf:type;
rr:objectMap [ rr:template "http://w3id.org/semcon/ns/seismic#SeismicActivity" ];
];
rr:predicateObjectMap [
rr:predicate scs:lastUpdate;
rr:objectMap <#getTime> ;
];
rr:predicateObjectMap [
rr:predicate scs:magnitude;
rr:objectMap [
rml:reference "magnitude" ;
rr:datatype xsd:float ;
];
];
rr:predicateObjectMap [
rr:predicate scs:magnitudeType;
rr:objectMap [
rml:reference "magnitudeType" ;
];
];
rr:predicateObjectMap [
rr:predicate scs:auth;
rr:objectMap [
rml:reference "auth" ;
rr:datatype xsd:string ;
];
];
rr:predicateObjectMap [
rr:predicate scs:sourceId;
rr:objectMap [
rml:reference "sourceId" ;
rr:datatype xsd:string ;
];
];
rr:predicateObjectMap [
rr:predicate wgs:alt ;
rr:objectMap [ rml:reference "alt" ; ];
rr:datatype xsd:float ;
];
rr:predicateObjectMap [
rr:predicate geo:asWKT ;
rr:objectMap [
carml:multiTemplate "Point({lat} {long})" ;
rr:datatype geo:wktLiteral ;
];
];
.
<#getTime>
rr:termType rr:Literal ;
rr:datatype xsd:dateTime;
fnml:functionValue [
rr:subjectMap [
rr:template "http://w3id.org/semcon/seismic/{lastUpdate}";
];
rr:predicateObjectMap [
rr:predicate fno:executes ;
rr:object func:timeConversion ;
];
rr:predicateObjectMap [
rr:predicate param:time ;
rr:objectMap [
rml:reference "lastUpdate" ;
rr:datatype xsd:string ;
];
];
rr:predicateObjectMap [
rr:predicate param:timeFormat ;
rr:objectMap [
rr:template "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'" ;
rr:datatype xsd:string ;
];
];
];
.
Hint: use the online Turtle validator http://ttl.summerofcode.be/ to check the validity of your mapping
The RML is to be provided in the DataMapping attributes of the container configuration. A complete configuration init_seismic.trig is available in this repository and a container can be started with the following command:
IMAGE=semcon/sc-sparql:latest; docker run -d --name seismic_sparql -e IMAGE_SHA256="$(docker image ls --no-trunc -q $IMAGE | cut -c8-)" -e IMAGE_NAME=$IMAGE -p 4000:3000 -p 4040:3030 $IMAGE /bin/init.sh "$(< init_seismic.trig)"Use the following command to store data in the container:
curl -H "Content-Type: application/json" -d "$(< seismic.json)" -X POST http://localhost:4000/api/dataUse the following command to query 10 triples:
curl -s 'http://localhost:4000/api/sparql/query?r=true&a=http://localhost:3000/api/data&q=SELECT%20%2A%20WHERE%20%7B%20%3Fa%20%3Fb%20%3Fc%7D%20LIMIT%2010' | jqOr use the SPARQL endpoint on port 4040:
curl http://localhost:4040/rdf/sparql?query=SELECT%20*%20WHERE%20%7B%20?a%20?b%20?c%7D%20LIMIT%2010Hint: the tool yasgui.org can be used as a webfrontend to perform SPARQL queries
An example for a more complex SPARQL query is the following time based FILTER statement:
prefix scs: <http://w3id.org/semcon/ns/seismic#>
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT ?point ?lastUpdate
WHERE {
?point rdf:type scs:SeismicActivity .
?point scs:lastUpdate ?lastUpdate .
FILTER (?lastUpdate > "2019-10-28T00:00:00"^^xsd:dateTime && ?lastUpdate < "2019-10-28T11:59:59"^^xsd:dateTime)
}
ORDER BY ?lastUpdate
Use URL encoding (or percent-encoding) to pass this query as parameter:
curl http://localhost:4040/rdf/sparql?query=prefix%20scs%3A%20%3Chttp%3A%2F%2Fw3id.org%2Fsemcon%2Fns%2Fseismic%23%3E%0Aprefix%20rdf%3A%20%3Chttp%3A%2F%2Fwww.w3.org%2F1999%2F02%2F22-rdf-syntax-ns%23%3E%0Aprefix%20xsd%3A%20%3Chttp%3A%2F%2Fwww.w3.org%2F2001%2FXMLSchema%23%3E%0A%0ASELECT%20%3Fpoint%20%3FlastUpdate%0AWHERE%20%7B%20%20%20%20%20%20%20%20%20%20%20%20%0A%09%3Fpoint%20rdf%3Atype%20scs%3ASeismicActivity%20.%0A%09%3Fpoint%20scs%3AlastUpdate%20%3FlastUpdate%20.%0A%20%20%20%09FILTER%20%28%3FlastUpdate%20%3E%20%222019-10-28T00%3A00%3A00%22%5E%5Exsd%3AdateTime%20%26%26%20%3FlastUpdate%20%3C%20%222019-10-28T11%3A59%3A59%22%5E%5Exsd%3AdateTime%29%0A%7D%0AORDER%20BY%20%3FlastUpdate%0AHint: the tool URL Decoder/Encoder produces compliant percent-encoded strings
Please report bugs and suggestions for new features using the GitHub Issue-Tracker and follow the Contributor Guidelines.
If you want to contribute, please follow these steps:
- Fork it!
- Create a feature branch:
git checkout -b my-new-feature - Commit changes:
git commit -am 'Add some feature' - Push into branch:
git push origin my-new-feature - Send a Pull Request