samples/connectors/src/main/java/org/apache/edgent/samples/connectors/elm327/Elm327Streams.java

/*
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regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
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  http://www.apache.org/licenses/LICENSE-2.0

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specific language governing permissions and limitations
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*/
package org.apache.edgent.samples.connectors.elm327;

import java.util.concurrent.TimeUnit;

import org.apache.edgent.connectors.serial.SerialDevice;
import org.apache.edgent.function.Supplier;
import org.apache.edgent.samples.connectors.elm327.runtime.CommandExecutor;
import org.apache.edgent.topology.TStream;

import com.google.gson.JsonArray;

/**
 * Streams fetching OBD-II data from an ELM327 through
 * a serial device.
 *
 * @see <a href="https://en.wikipedia.org/wiki/ELM327">ELM327</a>
 */
public class Elm327Streams {
	
    /**
     * Periodically execute a number of ELM327 commands.
     * Each tuple on the returned stream is a JSON array containing
     * the result for each command.
     * <BR>
     * Each result is a JSON object containing the
     * {@link Cmd#id() command identifier} with key {@link Cmd#PID pid}
     * and any result set by the individual command, typically with
     * the key {@link Cmd#VALUE value}.
     * 
     * @param device Serial device the ELM327 is connected to.
     * @param period Period to poll.
     * @param unit Unit of {@code period}.
     * @param cmds Commands to execute.
     * @return Stream containing the results of the command exections.
     */
	public static TStream<JsonArray> poll(SerialDevice device, long period, TimeUnit unit, Cmd ... cmds) {
		
		Supplier<JsonArray> data = device.getSource(
				port ->
		{
			JsonArray array = new JsonArray();
			for (Cmd cmd : cmds) {
				array.add(CommandExecutor.execute(cmd, port.getOutput(), port.getInput()));
			}
			return array;
			
		});
		
		return device.topology().poll(data, period, unit);

	}
}