cqels_shim.StdinStream.java Source code

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Here is the source code for cqels_shim.StdinStream.java

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/*
 *   Copyright 2015 Andreas Mosburger
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 */

package cqels_shim;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

import org.deri.cqels.engine.ExecContext;
import org.deri.cqels.engine.RDFStream;
import com.hp.hpl.jena.graph.Node;

import org.json.simple.JSONObject;
import org.json.simple.JSONArray;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

/**
 * reads RDF triples from stdin and streams them to cqels
 * a triple is expected as an array in JSON
 */
public class StdinStream extends RDFStream implements Runnable {
    boolean stop = false;
    long sleep = 0;

    /**
     * @param context
     * @param uri
     */
    public StdinStream(ExecContext context, String uri) {
        super(context, uri);
    }

    @Override
    public void stop() {
        stop = true;
    }

    /**
     * @param rate
     */
    public void setRate(int rate) {
        sleep = 1000 / rate;
    }

    /**
     * start listening to stdin and forwarding to cqels
     */
    public void run() {
        try {
            JSONParser parser = new JSONParser();
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            String line;

            while ((line = reader.readLine()) != null && !stop) {
                try {
                    Object obj = parser.parse(line);
                    JSONArray array = (JSONArray) obj;

                    //stream the triple
                    stream(n((String) array.get(0)), n((String) array.get(1)), n((String) array.get(2)));
                } catch (ParseException pe) {
                    System.err.println("Error when parsing input, incorrect JSON.");
                }

                if (sleep > 0) {
                    try {
                        Thread.sleep(sleep);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static Node n(String st) {
        return Node.createURI(st);
    }
}