Transformations.java

// camel-k: language=java property=file:transformation.properties 
// camel-k: dependency=camel:jacksonxml 
// camel-k: dependency=camel:http 
// camel-k: dependency=camel:gson
// camel-k: dependency=camel:jdbc 
// camel-k: dependency=camel:csv 
// camel-k: dependency=mvn:org.postgresql:postgresql:jar:42.2.13 
// camel-k: dependency=mvn:org.apache.commons:commons-dbcp2:jar:2.7.0

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.camel.AggregationStrategy;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.model.dataformat.JsonLibrary;
import org.apache.camel.processor.aggregate.AbstractListAggregationStrategy;

public class Transformations extends RouteBuilder {

  @Override
  public void configure() throws Exception {

    // The following processors store relevant info as properties
    Processor processCsv = new CSVProcessor();
    Processor processXML = new XMLProcessor();

    // Preparing properties to build a GeoJSON Feature
    Processor processDB = new DBProcessor();

    // Just collects all features in a collection for the final GeoJSON
    Processor buildGeoJSON = new GeoJSONProcessor();

    // Aggregate all messages into one message with the list of bodies
    AggregationStrategy aggregationStrategy = new CollectToListStrategy();

    // This is the actual route
    from("timer:java?period=100000")
        // Reference URL for air quality e-Reporting on EEA
        // https://www.eea.europa.eu/data-and-maps/data/aqereporting-2

        // We start by reading our data.csv file, looping on each row
        .to("{{source.csv}}").unmarshal("customCSV").split(body()).streaming()

        // we store on exchange properties all the data we are interested in
        .process(processCsv)

        // on each row, we query an XML API service
        .setBody().constant("").setHeader(Exchange.HTTP_METHOD, constant("GET"))
        .setHeader(Exchange.HTTP_QUERY, simple("lat=${exchangeProperty.lat}&lon=${exchangeProperty.lon}&format=xml"))
        .to("https://nominatim.openstreetmap.org/reverse").unmarshal().jacksonxml()

        // we store on exchange properties all the data we are interested in
        .process(processXML)

        // now we query the postgres database for more data
        .setBody().simple("SELECT info FROM descriptions WHERE id like '${exchangeProperty.pollutant}'")
        .to("jdbc:postgresBean?readSize=1")

        // we store on exchange properties all the data we are interested in
        .process(processDB)

        // we collect all rows into one message
        .aggregate(constant(true), aggregationStrategy).completionSize(5).process(buildGeoJSON).marshal()
        .json(JsonLibrary.Gson)

        .to("log:info?showBody=true")
        // and finally store the result on the postgres database
        .setBody(simple("INSERT INTO measurements (geojson) VALUES ('${body}')")).to("jdbc:postgresBean")

        // Write some log to know it finishes properly
        .log("Information stored");
  }

  private final class CollectToListStrategy extends AbstractListAggregationStrategy<Object> {
    @Override
    public Object getValue(Exchange exchange) {
      return exchange.getMessage().getBody();
    }
  }

  private final class GeoJSONProcessor implements Processor {
    @Override
    public void process(Exchange exchange) throws Exception {
      Map<String, Object> res = new HashMap<String, Object>();
      res.put("features", exchange.getMessage().getBody());
      res.put("type", "FeatureCollection");
      exchange.getIn().setBody(res);
    }
  }

  private final class DBProcessor implements Processor {
    @Override
    public void process(Exchange exchange) throws Exception {
      @SuppressWarnings("unchecked")
      List<Object> body = exchange.getMessage().getBody(List.class);

      Map<String, Object> outputBody = new HashMap<String, Object>();
      outputBody.put("unit", exchange.getProperty("unit"));
      outputBody.put("level", exchange.getProperty("level"));
      outputBody.put("pollutant", exchange.getProperty("pollutant"));
      outputBody.put("address", exchange.getProperty("address"));

      // If we got any response from the DB, add it
      if (body.size() > 0) {
        outputBody.put("info", body.get(0).toString());
      }

      List<String> coordinates = new ArrayList<String>();
      coordinates.add(exchange.getProperty("lat", "").toString());
      coordinates.add(exchange.getProperty("lon", "").toString());

      Map<String, Object> geometry = new HashMap<String, Object>();
      geometry.put("type", "Point");
      geometry.put("coordinates", coordinates);

      Map<String, Object> res = new HashMap<String, Object>();
      res.put("geometry", geometry);
      res.put("properties", outputBody);
      res.put("type", "Feature");

      exchange.getIn().setBody(res);
    }
  }

  private final class XMLProcessor implements Processor {
    @Override
    public void process(Exchange exchange) throws Exception {
      @SuppressWarnings("unchecked")
      Map<String, String> body = exchange.getIn().getBody(Map.class);
      exchange.setProperty("address", body.get("addressparts"));
    }
  }

  private final class CSVProcessor implements Processor {
    @Override
    public void process(Exchange exchange) throws Exception {
      @SuppressWarnings("unchecked")
      Map<String, String> body = exchange.getIn().getBody(Map.class);

      if (body != null) {
        extractValue(exchange, body, "Latitude of station", "lat");
        extractValue(exchange, body, "Longitude of station", "lon");
        extractValue(exchange, body, "Unit", "unit");
        extractValue(exchange, body, "Air pollution level", "level");
        extractValue(exchange, body, "Air pollutant", "pollutant");
      }
    }

    private void extractValue(Exchange exchange, Map<String, String> body, String param, String keyName) {
      if (body.containsKey(param)) {
        exchange.setProperty(keyName, body.get(param));
      }
    }
  }
}