be.ugent.rml.conformer.MappingConformer Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of rmlmapper Show documentation
The RMLMapper executes RML rules to generate high quality Linked Data from multiple originally (semi-)structured data sources.
The newest version!
package be.ugent.rml.conformer;

import be.ugent.rml.Utils;
import be.ugent.rml.store.QuadStore;
import be.ugent.rml.term.NamedNode;
import be.ugent.rml.term.Term;

import java.io.FileNotFoundException;
import java.util.List;
import java.util.Map;

import static be.ugent.rml.NAMESPACES.*;

/**
 * Only validates by checking for at least one TriplesMap.
 * Converts mapping files to W3C's Knowledge Graph Community Group RML from RML and R2RML.
 * InputStream of mapping file is used to create a store. TriplesMaps in store that need conversion
 * are detected by applying the converters detection methods and saved. convert tries to convert these
 * to W3C RML. Exceptions can be raised during validation and conversion, which the caller has to handle.
 * Output of detect() informs if convert() should be used to convert to valid W3C RML.
 * The validated RML can be returned as a QuadStore with getStore().
 */
public class MappingConformer {

    public enum Dialect {
        RML, // Old RML
        R2RML, // W3C's R2RML
        RML2 // W3C's Knowledge Graph Construction Community Group RML
    }

    private QuadStore store;
    private Map mappingOptions;

    /**
     * Create MappingConformer from InputStream of mapping file in RDF.
     *
     * @param store A QuadStore with the mapping rules.
     * @throws FileNotFoundException
     */
    public MappingConformer(QuadStore store) throws Exception {
        this(store, null);
    }

    /**
     * Create MappingConformer from InputStream of mapping file in RDF.
     *
     * @param store A QuadStore with the mapping rules.
     * @throws FileNotFoundException
     */
    public MappingConformer(QuadStore store, Map mappingOptions) throws Exception {
        this.store = store;
        this.mappingOptions = mappingOptions;
    }

    /**
     * This method makes the QuadStore conformant to the RML spec.
     *
     * @return True if the store had to be updated, else false.
     * @throws Exception if something goes wrong during detection or conversion.
     */
    public boolean conform() throws Exception {
        this.detect();
        return false;
    }

    /**
     * Detect if mapping file is valid W3C RML.
     *
     * @return Dialect of the mapping file. Null if invalid.
     * @throws Exception if invalid or unconvertable
     */
    private void detect() throws Exception {
        // convert rml
        RMLConverterNew converter = new RMLConverterNew(store);
        converter.convert(mappingOptions);

        // Check if we have a valid TriplesMap.
        List triplesMaps = Utils.getSubjectsFromQuads(store.getQuads(null, new NamedNode(RML2 + "logicalSource"), null));
        if (triplesMaps.isEmpty()) {
            throw new Exception("Mapping requires at least one TriplesMap");
        }

        // Triples Maps need a subject Map
        List triplesMaps2 = Utils.getSubjectsFromQuads(store.getQuads(null, null, new NamedNode(RML2 + "TriplesMap")));
        for (Term triplesMap : triplesMaps2) {
            if (!store.contains(triplesMap, new NamedNode(RML2 + "subjectMap"), null)) {
                throw new Exception("TriplesMap requires a subject map");
            }
        }
    }


    /**
     * Debugging helper function to check difference of models
     *
     * @param store QuadStore which subtracts
     * @return boolean this.store isSubset of  given store
     */
    boolean differenceInConformer(QuadStore store) {
        return this.store.isSubset(store);
    }

    /**
     * Debugging helper function to check difference of models
     *
     * @param store QuadStore which subtracts
     * @return boolean given store isSubset of store
     */
    boolean differenceInGivenStore(QuadStore store) {
        return store.isSubset(this.store);
    }

    /**
     * Get a valid QuadStore
     *
     * @return a valid QuadStore
     */
    public QuadStore getStore() {
        return store;
    }
}