org.charvolant.argushiigi.server.ReferenceQueryResource.java Source code

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Here is the source code for org.charvolant.argushiigi.server.ReferenceQueryResource.java

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/*
 *  $Id$
 *
 * Copyright (c) 2013 Doug Palmer
 *
 * See LICENSE for licensing details
 */
package org.charvolant.argushiigi.server;

import java.util.Comparator;
import java.util.Locale;
import java.util.logging.Level;

import org.charvolant.argushiigi.ontology.DisplaySorter;
import org.json.JSONArray;
import org.json.JSONObject;
import org.restlet.data.Reference;
import org.restlet.data.Status;
import org.restlet.ext.json.JsonRepresentation;
import org.restlet.representation.Representation;
import org.restlet.representation.StringRepresentation;
import org.restlet.resource.Get;
import org.restlet.resource.ResourceException;
import org.restlet.resource.ServerResource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.Resource;
import com.hp.hpl.jena.rdf.model.Statement;
import com.hp.hpl.jena.rdf.model.StmtIterator;
import com.hp.hpl.jena.vocabulary.OWL;
import com.hp.hpl.jena.vocabulary.RDF;

/**
 * A query end-point for queries for references to a resource.
 * <p>
 * Generates a JSON document listing all the results.
 * 
 * @author Doug Palmer <doug@charvolant.org>
 *
 */
public class ReferenceQueryResource extends ServerResource {
    @SuppressWarnings("unused")
    private static final Logger logger = LoggerFactory.getLogger(ReferenceQueryResource.class);

    public static final String PARAM_RESOURCE = "resource";

    /** The application */
    private ServerApplication application;
    /** The model */
    private Model model;
    /** The display sorter (from the application) */
    private DisplaySorter sorter;

    /**
     * Constructor for a query resource.
     *
     */
    public ReferenceQueryResource() {
    }

    /**
     * Initialise the resource by collecting the contextual
     * information from the {@link ServerApplication} application. 
     *
     * @see org.restlet.resource.UniformResource#doInit()
     */
    @Override
    protected void doInit() throws ResourceException {
        super.doInit();
        this.application = (ServerApplication) this.getApplication();
        this.model = this.application.getDataset();
        this.sorter = this.application.getSorter();
    }

    /**
     * Get a list of matching resources as a JSON document.
     *
     * @see org.restlet.resource.ServerResource#get()
     */
    @Get
    public Representation get() {
        String resource = Reference.decode(this.getQueryValue(this.PARAM_RESOURCE));

        try {
            JSONObject wrap = new JSONObject();
            JSONArray result = new JSONArray();
            StmtIterator si = this.model.listStatements(null, null, this.model.createResource(resource));
            Comparator<Resource> classComparator = this.sorter.getClassComparator();

            while (si.hasNext()) {
                Statement s = si.next();
                Resource res = s.getSubject();

                if (res.isURIResource()) {
                    JSONObject obj = new JSONObject();
                    Reference ref = this.application.getLocalRef(new Reference(res.getURI()));
                    StmtIterator ci = this.model.listStatements(res, RDF.type, (Resource) null);
                    Resource cls = null;

                    obj.put("name", this.sorter.getName(s.getSubject(), Locale.ENGLISH));
                    obj.put("uri", s.getSubject().getURI());
                    obj.put("href", ref);
                    while (ci.hasNext()) {
                        Resource c = ci.next().getResource();

                        if (c.isAnon())
                            continue;
                        if (cls == null || classComparator.compare(cls, c) > 0)
                            cls = c;
                    }
                    if (cls == null)
                        cls = OWL.Thing;
                    ref = this.application.getLocalRef(new Reference(cls.getURI()));
                    obj.put("cls", this.sorter.getName(cls, Locale.ENGLISH));
                    obj.put("clsUri", cls.getURI());
                    obj.put("clsHref", ref);
                    result.put(obj);
                }
            }
            wrap.put("aaData", result);
            return new JsonRepresentation(wrap);
        } catch (Exception ex) {
            this.application.getLogger().log(Level.SEVERE, "Unable to get references to " + resource, ex);
            this.getResponse().setStatus(Status.SERVER_ERROR_INTERNAL, ex);
            return new StringRepresentation(ex.getMessage());
        }
    }

}