Load Data

There are a few mechanisms to load data

Web REST endpoint

The War sets up a Web REST endpoint at http://server/web.rya/loadrdf that allows POST data to get loaded into the Rdf Store. This short tutorial will use Java code to post data.

First, you will need data to load and will need to figure out what format that data is in.

For this sample, we will use the following N-Triples:

<http://mynamespace/ProductType1> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://mynamespace/ProductType> .
<http://mynamespace/ProductType1> <http://www.w3.org/2000/01/rdf-schema#label> "Thing" .
<http://mynamespace/ProductType1> <http://purl.org/dc/elements/1.1/publisher> <http://mynamespace/Publisher1> .

Save this file somewhere $RDF_DATA

Second, use the following Java code to load data to the REST endpoint:

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;

public class LoadDataServletRun {

    public static void main(String[] args) {
        try {
            final InputStream resourceAsStream = Thread.currentThread().getContextClassLoader()
                    .getResourceAsStream("$RDF_DATA");
            URL url = new URL("http://server/web.rya/loadrdf" +
                    "?format=N-Triples" +
                    "");
            URLConnection urlConnection = url.openConnection();
            urlConnection.setRequestProperty("Content-Type", "text/plain");
            urlConnection.setDoOutput(true);

            final OutputStream os = urlConnection.getOutputStream();

            int read;
            while((read = resourceAsStream.read()) >= 0) {
                os.write(read);
            }
            resourceAsStream.close();
            os.flush();

            BufferedReader rd = new BufferedReader(new InputStreamReader(
                    urlConnection.getInputStream()));
            String line;
            while ((line = rd.readLine()) != null) {
                System.out.println(line);
            }
            rd.close();
            os.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Compile and run this code above, changing the references for $RDF_DATA and the url that your Rdf War is running at.

The default “format” is RDF/XML, but these formats are supported : RDFXML, NTRIPLES, TURTLE, N3, TRIX, TRIG.

Bulk Loading data

Bulk loading data is done through Map Reduce jobs

Bulk Load RDF data

This Map Reduce job will read files into memory and parse them into statements. The statements are saved into the store. Here is an example for storing in Accumulo:

hadoop jar target/rya.mapreduce-3.2.10-SNAPSHOT-shaded.jar org.apache.rya.accumulo.mr.RdfFileInputTool -Dac.zk=localhost:2181 -Dac.instance=accumulo -Dac.username=root -Dac.pwd=secret -Drdf.tablePrefix=triplestore_ -Drdf.format=N-Triples /tmp/temp.ntrips

Options:

• rdf.tablePrefix : The tables (spo, po, osp) are prefixed with this qualifier. The tables become: (rdf.tablePrefix)spo,(rdf.tablePrefix)po,(rdf.tablePrefix)osp
• ac.* : Accumulo connection parameters
• rdf.format : See RDFFormat from RDF4J, samples include (Trig, N-Triples, RDF/XML)
• sc.use_freetext, sc.use_geo, sc.use_temporal, sc.use_entity : If any of these are set to true, statements will also be added to the enabled secondary indices.
• sc.freetext.predicates, sc.geo.predicates, sc.temporal.predicates: If the associated indexer is enabled, these options specify which statements should be sent to that indexer (based on the predicate). If not given, all indexers will attempt to index all statements.

The argument is the directory/file to load. This file needs to be loaded into HDFS before running. If loading a directory, all files should have the same RDF format.

Direct RDF4J API

Here is some sample code to load data directly through the RDF4J API. (Loading N-Triples data) You will need at least accumulo.rya-<version>, rya.api, rya.sail.impl on the classpath and transitive dependencies. I find that Maven is the easiest way to get a project dependency tree set up.

final RdfCloudTripleStore store = new RdfCloudTripleStore();
AccumuloRdfConfiguration conf = new AccumuloRdfConfiguration();
AccumuloRyaDAO dao = new AccumuloRdfDAO();
Connector connector = new ZooKeeperInstance("instance", "zoo1,zoo2,zoo3").getConnector("user", "password");
dao.setConnector(connector);
conf.setTablePrefix("rya_");
dao.setConf(conf);
store.setRdfDao(dao);

Repository myRepository = new RyaSailRepository(store);
myRepository.initialize();
RepositoryConnection conn = myRepository.getConnection();

//load data from file
final File file = new File("ntriples.ntrips");
conn.add(new FileInputStream(file), file.getName(),
        RDFFormat.NTRIPLES, new Resource[]{});

conn.commit();

conn.close();
myRepository.shutDown();