macchina.io EDGE Technology

Web User Interface

macchina.io EDGE comes with a built-in web server providing different web apps for device management, testing and getting started with JavaScript development. These can be modified or replaced with a device-specific interface and apps. In any case, the web server is just another plug-in, so it can even be removed entirely if not needed.

The Launcher is the starting point of the web user interface.

The Sensor Log app logs and graphs sensor values.

The Device Tree app shows datapoints and sensor data.

The GNSS app shows the location of the device.

The Settings app edits configuration settings.

The Console app displays logging output.

The Playground app edits and runs JavaScript code.

The Bundles app manages bundles.

JavaScript

Sensors

Sensors and other devices are presented as services that can be searched for based on various properties. In the following sample, we look for an ambient light (luminance) and a temperature sensor. The code that looks for sensors is implemented as a module and can be imported using the familiar require() function.

const sensors = {};

const ambientLightRefs = serviceRegistry.find('io.macchina.physicalQuantity == "luminance"');
if (ambientLightRefs.length > 0)
{
    sensors.ambientLight = ambientLightRefs[0].instance();
    logger.information('Ambient Light: %s', sensors.ambientLight.getPropertyString('name'));
}

const temperatureRefs = serviceRegistry.find('io.macchina.physicalQuantity == "temperature"');
if (temperatureRefs.length > 0)
{
    sensors.temperature = temperatureRefs[0].instance();
    logger.information('Temperature: %s', sensors.temperature.getPropertyString('name'));
}

module.exports = sensors;

Database

Once we have a sensor object, we can get a callback whenever the measured value changes. In the following example, we write the current sensor value into a SQLite database, together with a timestamp.

var data = require('data');
const sensors = require('sensors.js');

const dbPath = application.config.getString('datalogger.database');
const dbSession = new data.DBSession('SQLite', dbPath);

sensors.temperature.on('valueChanged', event => {
        dbSession.execute('INSERT INTO datalog VALUES (?, ?)',
            Date(),
            event.data);
    });

Serial Port

Many devices provide a serial (UART) interface and support a simple text-based protocol. It's easy to process data received from such devices.

var serial = null;
const serialRef = serviceRegistry.findByName('io.macchina.serialport#0');
if (serialRef)
{
    serial = serialRef.instance();
    logger.notice('SerialDevice found: %s', serial.getPropertyString("device"));
}

serial.setFeature('events', true);
serial.setPropertyString('delimiters', '\n');
serial.setPropertyDouble('timeout', 0.1);
serial.on('lineReceived', (line) => {
        logger.notice('Received: %s', line.data);
    });

Cloud Services

The following example shows how to send data to a cloud service providing a REST interface. We periodically obtain temperature and ambient light measurements and send them to the AirVantage M2M Cloud service.

const net = require('net');
const sensors = require('sensors.js');

const username = application.config.getString("airvantage.username");
const password = application.config.getString("airvantage.password");

setInterval(
    function()
    {
        const httpRequest = new net.HTTPRequest('POST', 'https://na.airvantage.net/device/messages');
        const epoch = 1000*DateTime().epoch; // seconds to milliseconds
        httpRequest.timeout = 10.0;
        httpRequest.authenticate(username, password);
        httpRequest.content = JSON.stringify(
            [
                {
                    "sensor.temperature":
                        [
                            {
                                "timestamp": epoch,
                                "value": sensors.temperature.value()
                            }
                        ],
                    "sensor.ambientLight":
                        [
                            {
                                "timestamp": epoch,
                                "value": sensors.ambientLight.value()
                            }
                        ]
                }
            ]
        );
        const httpResponse = httpRequest.send();
        if (httpResponse.status != 200)
        {
            logger.error('Failed sending data to AirVantage: %s', httpResponse.reason);
        }
    },
    30000);

The above sample blocks in send() until the HTTP request has been completed. HTTP requests can also be sent asynchronously. In this case, a callback function will be called when the request has completed.

// ...
        httpRequest.send(
            function (result)
            {
                if (result.error)
                {
                    logger.error(result.error);
                }
                else if (result.response.status != 200)
                {
                    logger.error('HTTP request failed: %s', result.response.reason);
                }
            });
        // ...

Servlets

The following example shows how to implement a servlet in JavaScript that reads sensor data from the SQLite database and formats it as JSON.

const data = require('data');

const dbPath = application.config.getString('logger.database');
const dbSession = new data.DBSession('SQLite', dbPath);
dbSession.pageSize = 20;

const recordSet = dbSession.execute('SELECT timestamp, temperature FROM datalog ORDER BY timestamp DESC');
response.contentType = 'application/json';
response.write(recordSet.toJSON());
response.send();