Event API Tutorial

Run the example

  1. Install and run the device gateway
  2. Download the Node.js client library
  3. Copy the root certificate of the gateway to your working directory. As default, the certificate(ca.crt) resides in cert of the installation directory.
  4. Change the gateway and the device information in example/event/test/test.js as needed.

     // the path of the root certificate
     const GATEWAY_CA_FILE = '../../../../cert/gateway/ca.crt';
    
     // the address of the gateway
     const GATEWAY_IP = '192.168.0.2';
     const GATEWAY_PORT = 4000;
    
     // the ip address of the target device
     const DEVICE_IP = '192.168.0.110';
     const DEVICE_PORT = 51211;
     const USE_SSL = false;
    
  5. Install packages.

     npm install
    
  6. Run.

     cd example/event/test
     node test.js
    

1. Connect to the gateway and the device

The example assumes you use the device gateway. For the master gateway or other connection options, refer to the Connect or ConnectMaster examples.

  var rootCa = fs.readFileSync(GATEWAY_CA_FILE);
  var sslCreds = grpc.credentials.createSsl(rootCa);
  var addr = `${GATEWAY_IP}:${GATEWAY_PORT}`;

  connect.initClient(addr, sslCreds);

  var deviceID = await connect.connectToDevice(DEVICE_IP, DEVICE_PORT, USE_SSL);

2. Initialize the event code map

Since V1.3, the event code map, event_code.json, is provided. You can use it in your application for looking up the short descriptions of event codes.

  function initCodeMap(filename) {
    var jsonData = fs.readFileSync(filename);
    codeMap = JSON.parse(jsonData);
  }

  function getEventString(eventCode, subCode) {
    for(entry of codeMap.entries) {
      if(eventCode == entry.event_code && subCode == entry.sub_code) {
        return entry.desc;
      }
    }

    return util.format('Unknown event(0x%s)', (eventCode | subCode).toString(16));
  }

  event.initCodeMap(CODE_MAP_FILE);

3. Receive realtime events

To receive realtime events from the devices, you have to do the followings.

  1. Enable monitoring on target devices.
  2. Subscribe to the event channel.
  3. Read the events from the channel.
  await event.enableMonitoring(devID);
  
  sub = event.subscribe(EVENT_QUEUE_SIZE);

  sub.on('data', (event) => {
    // do something with the event
    console.log('Event: ', event.toObject());
  });

4. Read event logs

When reading event logs, you can specify the starting index and the maximum number of events.

  const events = util.toObjectArray(await event.getLog(devID, firstEventID, MAX_NUM_EVENT));

  for(i = 0; i < events.length; i++) {
    printEvent(events[i]);
  }

You can also specify a filter to limit your search.

  var eventFilter = new event.eventMessage.EventFilter();
  eventFilter.setEventcode(events[0].eventcode);

  const filteredEvents = util.toObjectArray(await event.getLogWithFilter(devID, firstEventID, MAX_NUM_EVENT, eventFilter));
  for(i = 0; i < filteredEvents.length; i++) {
    printEvent(filteredEvents[i]);
  }