plc4j/examples/hello-connectivity-kafka/src/main/java/org/apache/plc4x/java/examples/connectivity/kafka/KafkaConnector.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
 with the License.  You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

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package org.apache.plc4x.java.examples.connectivity.kafka;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;
import com.google.gson.JsonArray;
import com.google.gson.JsonObject;
import org.apache.commons.lang3.StringUtils;
import org.apache.edgent.connectors.kafka.KafkaProducer;
import org.apache.edgent.function.Supplier;
import org.apache.edgent.providers.direct.DirectProvider;
import org.apache.edgent.topology.TStream;
import org.apache.edgent.topology.Topology;
import org.apache.plc4x.edgent.PlcConnectionAdapter;
import org.apache.plc4x.edgent.PlcFunctions;
import org.apache.plc4x.java.api.exceptions.PlcException;
import org.apache.plc4x.java.api.messages.PlcReadRequest;
import org.apache.plc4x.java.api.messages.PlcReadResponse;
import org.apache.plc4x.java.examples.connectivity.kafka.model.Configuration;
import org.apache.plc4x.java.examples.connectivity.kafka.model.PlcFieldConfig;
import org.apache.plc4x.java.examples.connectivity.kafka.model.PlcMemoryBlock;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

public class KafkaConnector {

    private static final Logger logger = LoggerFactory.getLogger(KafkaConnector.class);

    private Configuration config;
    private PlcConnectionAdapter plcAdapter;

    private KafkaConnector(String propsPath) {
        if(StringUtils.isEmpty(propsPath)) {
            logger.error("Empty configuration file parameter");
            throw new IllegalArgumentException("Empty configuration file parameter");
        }
        File propsFile = new File(propsPath);
        if(!(propsFile.exists() && propsFile.isFile())) {
            logger.error("Invalid configuration file {}", propsFile.getPath());
            throw new IllegalArgumentException("Invalid configuration file " + propsFile.getPath());
        }
        ObjectMapper mapper = new ObjectMapper(new YAMLFactory());
        try {
            config = mapper.readValue(propsFile, Configuration.class);
            plcAdapter = new PlcConnectionAdapter(config.getPlcConfig().getConnection());
        } catch (IOException e) {
            logger.error("Error parsing configuration", e);
        }
    }

    private void run() throws PlcException {
        DirectProvider dp = new DirectProvider();
        Topology top = dp.newTopology("kafka-bridge");

        // Build the entire request.
        PlcReadRequest.Builder builder = plcAdapter.readRequestBuilder();
        for(PlcMemoryBlock plcMemoryBlock : config.getPlcConfig().getPlcMemoryBlocks()) {
            for (PlcFieldConfig address : config.getPlcConfig().getPlcFields()) {
                builder = builder.addItem(plcMemoryBlock.getName() + "/" + address.getName(),
                    "DATA_BLOCKS/" + plcMemoryBlock.getAddress() + "/" + address.getAddress());
            }
        }
        PlcReadRequest readRequest = builder.build();

        // Create a supplier that is able to read the batch we just created.
        Supplier<PlcReadResponse> plcSupplier = PlcFunctions.batchSupplier(plcAdapter, readRequest);

        // Start polling our plc source in the given interval.
        TStream<PlcReadResponse> source = top.poll(plcSupplier, config.getPollingInterval(), TimeUnit.MILLISECONDS);

        // Convert the byte into a string.
        TStream<String> jsonSource = source.map(value -> {
            JsonObject jsonObject = new JsonObject();
            value.getFieldNames().forEach(fieldName -> {
                if(value.getNumberOfValues(fieldName) == 1) {
                    jsonObject.addProperty(fieldName, value.getObject(fieldName).toString());
                } else if (value.getNumberOfValues(fieldName) > 1) {
                    JsonArray values = new JsonArray();
                    value.getAllBytes(fieldName).forEach(values::add);
                    jsonObject.add(fieldName, values);
                }
            });
            return jsonObject.toString();
        });

        // Publish the stream to the topic. The String tuple is the message value.
        // Create the Kafka Producer broker connector
        Map<String,Object> kafkaConfig = createKafkaConfig();
        KafkaProducer kafka = new KafkaProducer(top, () -> kafkaConfig);
        kafka.publish(jsonSource, config.getKafkaConfig().getTopicName());

        dp.submit(top);
    }

    private Map<String,Object> createKafkaConfig() {
        Map<String,Object> kafkaConfig = new HashMap<>();
        kafkaConfig.put("bootstrap.servers", config.getKafkaConfig().getBootstrapServers());
        if(config.getKafkaConfig().getProperties() != null) {
            kafkaConfig.putAll(config.getKafkaConfig().getProperties());
        }
        return kafkaConfig;
    }

    public static void main(String[] args) throws Exception {
        if(args.length != 1) {
            System.out.println("Usage: KafkaBridge {path-to-kafka-connector.yml}");
        }
        KafkaConnector kafkaBridge = new KafkaConnector(args[0]);
        kafkaBridge.run();
    }

}