Статьи

Где я? Сбор данных GPS с Apache Camel

Август 22, 2017

Одним из наиболее популярных требований к полевым устройствам, используемым в системах IoT, является предоставление текущего местоположения GPS этого устройства и отправка этой информации в центр обработки данных. В этой статье я расскажу вам, как  Apache Camel  может превратить микрокомпьютер Linux с полным стеком (например, Raspberry Pi) в устройство, собирающее координаты GPS.

Какой GPS-модуль выбрать?

На рынке доступно множество GPS-приемников. BU353  является одним из самых дешевых и самых популярных единиц GPS. Его можно подключить к компьютеру через порт USB. Если вы ищете хороший и дешевый GPS-приемник для вашего IoT-решения, вам обязательно следует приобрести этот аппарат.

На рисунке ниже представлен BU353, подключенный к устройству Raspberry Pi через порт USB.

При желании вы можете оснастить свой Pi внешней аккумуляторной батареей, например,  GOODRAM Power Bank P661 . Оснащенный внешним источником питания, вы можете взять свою мобильную систему GPS в автомобиле или на улице. Батарея значительно упрощает тестирование в полевой части вашего решения.

Как верблюд может помочь мне?

Camel GPS BU353 component can be used to read the current GPS information from that device. With Camel GPS BU353 you can just connect the receiver to your computer’s USB port and read the GPS data — the component will make sure that GPS daemon is up, running, and switched to the NMEA mode. The component also takes care of parsing the NMEA data read from the serial port, so you can enjoy the GPS data wrapped into the com.github.camellabs.iot.component.gps.bu353.ClientGpsCoordinates POJO objects (which in turn are forwarded to your Camel routes).

Show Me the Code

In order to take advantage of the Camel GPS BU353 you have to add the following dependency to your Maven project:

    <dependency>
      <groupId>com.github.camel-labs</groupId>
      <artifactId>camel-gps-bu353</artifactId>
      <version>0.1.1</version>
    </dependency>

The BU353 component supports only consumer endpoints — it makes sense as GPS component is used to read, not write, GPS data. The BU353 consumer is the polling one, i.e. it periodically asks the GPS device for the current coordinates. The Camel endpoint URI format for the BU353 consumer is as follows:

    gps-bu353:label

Where label can be replaced with any text label:

    from("gps-bu353:current-position").
      to("file:///var/gps-coordinates");

The Camel route presented above reads the current GPS coordinates every 5 seconds and saves these into the /var/gps-coordinates directory. Each GPS coordinates pair is saved into a dedicated file. The complete runnable example of the route above is presented in the code snippet below. I use Camel Spring Boot support to start the Camel context and load the route definition:

@SpringBootApplication
public class GpsReader extends FatJarRouter {

  public void configure() throws Exception {
    from("gps-bu353:current-position").
      to("file:///var/gps-coordinates");
  }

}

BU353 consumer receives the com.github.camellabs.iot.component.gps.bu353.ClientGpsCoordinates instances. ClientGpsCoordinates class is a convenient POJO wrapper around the GPS data:

  ConsumerTemplate consumerTemplate = camelContext.createConsumerTemplate();
  ClientGpsCoordinates currentPosition = 
    consumerTemplate.receiveBody("gps-bu353:current-position", ClientGpsCoordinates.class);

  String deviceId = currentPosition.clientId();
  Date taken = currentPosition.timestamp();
  double latitude = currentPosition.lat();
  double longitude = currentPosition.lng();

ClientGpsCoordinates class name is prefixed with the Client keyword to indicate that these coordinates have been created on the device, not on the server side of the IoT solution.

Process Manager

Process manager is used by the BU353 component to execute Linux commands responsible for starting GPSD daemon and configuring the GPS receiver to provide GPS coordinates in the NMEA mode. If for some reason you would like to change the default implementation of the process manager used by Camel (i.e. com.github.camellabs.iot.utils.process.DefaultProcessManager), you can set it on the component level:

    GpsBu353Component bu353 = new GpsBu353Component();
    bu353.setProcessManager(new CustomProcessManager());
    camelContext.addComponent("gps-bu353", bu353);

If the custom process manager is not set on the component, Camel will try to find the manager instance in the registry. So for example for the Spring application, you can just configure the manager as the bean:

    @Bean
    ProcessManager myProcessManager() {
        new CustomProcessManager();
    }

The custom process manager may be useful if for some reasons your Linux distribution requires executing some unusual commands in order to make the GPSD up and running.

What’s Next?

Do geographical capabilities of the Camel seem compelling to you? Then you should also Camel Geocoder component which can be used to easily convert GPS coordinates collected via Camel into the human readable street address. Also stay tuned for the geofencing features coming soon to the Camel IoT Labs project.

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