TimeSeriesRDFStream.java

import org.apache.jena.query.*;
import org.apache.jena.rdf.model.Model;
import org.apache.jena.rdf.model.ModelFactory;

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

public class TimeSeriesRDFStream {
    public static void main(String[] args) {
        // Create a scheduled executor service to fetch data every minute
        ScheduledExecutorService executorService = Executors.newScheduledThreadPool(1);

        // Schedule the task to run every minute
        executorService.scheduleAtFixedRate(() -> {
            fetchAndProcessRDFData();
        }, 0, 1, TimeUnit.MINUTES);
    }

    private static void fetchAndProcessRDFData() {
        // Create an empty model
        Model model = ModelFactory.createDefaultModel();

        // URL containing RDF time series data
        String rdfUrl = "http://example.com/timeseries.rdf"; // Replace with the actual URL

        try {
            // Read the RDF data from the URL
            model.read(rdfUrl);

            // Define a SPARQL query to extract time series data
            String queryString =
                "PREFIX ex: <http://example.com/schema/> " +
                "SELECT ?timestamp ?value " +
                "WHERE { " +
                "  ?observation ex:hasTimestamp ?timestamp ; " +
                "               ex:hasValue ?value . " +
                "} " +
                "ORDER BY ?timestamp";

            // Create a query
            Query query = QueryFactory.create(queryString);

            // Execute the query and obtain results
            try (QueryExecution qe = QueryExecutionFactory.create(query, model)) {
                ResultSet results = qe.execSelect();

                // Output query results
                System.out.println("\nUpdated Data:");
                while (results.hasNext()) {
                    QuerySolution solution = results.nextSolution();
                    String timestamp = solution.getLiteral("timestamp").getString();
                    double value = solution.getLiteral("value").getDouble();
                    System.out.println("Timestamp: " + timestamp + ", Value: " + value);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}