connectors/rabbitmq/src/main/java/org/apache/edgent/connectors/rabbitmq/RabbitmqConsumer.java

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package org.apache.edgent.connectors.rabbitmq;

import org.apache.edgent.connectors.rabbitmq.runtime.RabbitmqConnector;
import org.apache.edgent.connectors.rabbitmq.runtime.RabbitmqSubscriber;
import org.apache.edgent.function.Function;
import org.apache.edgent.function.Supplier;
import org.apache.edgent.topology.TStream;
import org.apache.edgent.topology.Topology;

import java.util.Map;

/**
 * {@code RabbitmqConsumer} is a consumer to consume messages from a RabbitMQ messaging broker
 * <p>
 * The connector uses and includes components from the RabbitMQ 3.7.3 release.
 * It has been successfully tested against 3.7.3.
 * For more information about RabbitMQ see <a href="http://www.rabbitmq.com/">http://www.rabbitmq.com/</a>
 * </p>
 * Smaple use:
 * <pre>{@code
 * Map<String, Object> config = new HashMap<>();
 * config.put(RabbitmqConfigKeyConstants.RABBITMQ_CONFIG_KEY_HOST, "127.0.0.1");
 * config.put(RabbitmqConfigKeyConstants.RABBITMQ_CONFIG_KEY_PORT, 5672);
 * String queue = "testQueue";
 *
 * Topology t = ...
 *
 * RabbitmqConsumer consumer = new RabbitmqConsumer(t, () -> configMap);
 * TStream<String> receivedStream = consumer.subscribe((byte[] bytes) -> new String(bytes), queue);
 *
 * //...
 * }
 * </pre>
 */
public class RabbitmqConsumer {

    private final RabbitmqConnector connector;
    private final Topology topology;

    /**
     * Create a consumer connector for consuming tuples from a RabbitMQ queue.
     * <p>
     * See the RabbitMQ java client document :
     * <a href="http://www.rabbitmq.com/api-guide.html">http://www.rabbitmq.com/api-guide.html</a>
     * The full config option please see RabbitMQ java client API Reference :
     * < a href="https://rabbitmq.github.io/rabbitmq-java-client/api/current/com/rabbitmq/client/ConnectionFactory.html">ConnectionFactory</>
     * </p>
     * @param topology topology to add to
     * @param config RabbitmqProducer configuration information.
     */
    public RabbitmqConsumer(Topology topology, Supplier<Map<String, Object>> config) {
        this.topology = topology;
        this.connector = new RabbitmqConnector(config);
    }

    /**
     * Subscribe to the specified topics and yield a stream of tuples from the published RabbitMQ records.
     *
     * @param toTupleFn A function that yields a tuple from a byte array,
     * @param queue the specified RabbitMQ queue
     * @param <T> A function that yields a tuple from a
     * @return stream of tuples
     */
    public <T> TStream<T> subscribe(Function<byte[], T> toTupleFn, String queue) {
        return topology.events(new RabbitmqSubscriber<>(connector, queue, toTupleFn));
    }

}