Connect 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 server information in example/connect/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;
   

5. Install packages.

    npm install
   

6. Run.

    cd example/connect/test
    node test.js
   

1. CLI

With the Command-Line Interface(CLI), you can test 5 functions related to connection management.

$ node test.js

===== Main Menu =====

(1) Search devices
(2) Connect to a device synchronously
(3) Manage asynchronous connections
(4) Accept devices
(5) Device menu
(q) Quit

>>>>> Select a menu:

(1) Search devices

To connect devices, you have to know their addresses and related options such as connection mode. By using Connect.SearchDevice, you can get these information in a subnet.

>>>>> Select a menu: 1
Searching devices in the subnet...
***** Found devices: 9
[ { deviceid: 540092578,
    type: 12,
    usedhcp: true,
    connectionmode: 0,
    ipaddr: '192.168.0.120',
    port: 51211,
    usessl: true },
  { deviceid: 544114231,
    type: 13,
    usedhcp: true,
    connectionmode: 0,
    ipaddr: '192.168.0.104',
    port: 51211,
    usessl: false },
  { deviceid: 846,
    type: 18,
    usedhcp: true,
    connectionmode: 0,
    ipaddr: '192.168.0.117',
    port: 51211,
    usessl: false },

(2) Connect to a device synchronously

The simplest way of connecting to a device is to use Connect.Connect.

>>>>> Select a menu: 2
Connect to a device synchronously...
>> Enter the IP address of the device: 192.168.0.104
>> Enter the port of the device (default: 51211):
>> Use SSL y/n (default: n):
Trying to connect to 192.168.0.104:51211...
Connected to 544114231

[TCP Connected]:  { deviceid: 544114231, status: 1, timestamp: 1584826654 }

(3) Manage asynchronous connections

When you have to manage permanent connections to multiple devices, asynchronous APIs would be a better choice. With these APIs, the gateway will handle connections to devices in the background. For example, if some devices are disconnected, the gateway will try to reconnect them automatically.

>>>>> Select a menu: 3

***** Async connections: 0
[]

===== Async Menu =====

(1) Add async connections
(2) Delete async connections
(3) Refresh the connection list
(q) Return to Main Menu

>>>>> Select a menu: 1
>> Enter the device ID (Press just ENTER if no more device): 540092578
>> Enter the IP address of the device: 192.168.0.120
>> Enter the port of the device (default: 51211):
>> Use SSL y/n (default: n): y
>> Enter the device ID (Press just ENTER if no more device): 939504224
>> Enter the IP address of the device: 192.168.0.110
>> Enter the port of the device (default: 51211):
>> Use SSL y/n (default: n):
>> Enter the device ID (Press just ENTER if no more device):
Adding asynchronous connections for 2 devices...

***** Async connections: 2
[ { deviceid: 540092578,
    connectionmode: 0,
    ipaddr: '192.168.0.120',
    port: 51211,
    status: 0,
    autoreconnect: true,
    usessl: true },
  { deviceid: 939504224,
    connectionmode: 0,
    ipaddr: '192.168.0.110',
    port: 51211,
    status: 0,
    autoreconnect: true,
    usessl: false } ]

[TCP Connected]:  { deviceid: 939504224, status: 1, timestamp: 1584826789 }

[TLS Connected]:  { deviceid: 540092578, status: 2, timestamp: 1584826791 }

(4) Accept devices

In some environments, the devices should connect to the gateway, not vice versa. For devices to connect to the gateway, you have to do the followings;

1. Change the connection mode to DEVICE_TO_SERVER using Connect.SetConnectionMode.
2. By default, the gateway will not accept any incoming connections. You have to add the devices to the accept filter using Connect.SetAcceptFilter.

>>>>> Select a menu: 4

***** Pending devices: 1
[ { deviceid: 939342898,
    ipaddr: '192.168.0.121',
    lasttry: 1584826860 } ]

***** Accept filter:  { allowall: false,
  deviceidsList: [],
  ipaddrsList: [],
  subnetmasksList: [] }

===== Accept Menu =====

(1) Add devices to the filter
(2) Delete devices from the filter
(3) Allow all devices
(4) Disallow all devices
(5) Refresh the pending device list
(q) Return to Main Menu

>>>>> Select a menu: 3

***** Accept filter:  { allowall: true,
  deviceidsList: [],
  ipaddrsList: [],
  subnetmasksList: [] }

[TLS Connected]:  { deviceid: 939342898, status: 2, timestamp: 1584826884 }

(5) Configure connection-related options

Apart from the IP address, there are two important options for device connections. You can change the connection mode using Connect.SetConnectionMode and enable/disable SSL using the SSL APIs.

>>>>> Select a menu: 5

***** Managed devices: 4
[ { deviceid: 939504224,
    connectionmode: 0,
    ipaddr: '192.168.0.110',
    port: 51211,
    status: 1,
    autoreconnect: true,
    usessl: false },
  { deviceid: 939342898,
    connectionmode: 1,
    ipaddr: '192.168.0.121',
    port: 0,
    status: 2,
    autoreconnect: false,
    usessl: true },
  { deviceid: 544114231,
    connectionmode: 0,
    ipaddr: '192.168.0.104',
    port: 51211,
    status: 1,
    autoreconnect: false,
    usessl: false },
  { deviceid: 540092578,
    connectionmode: 0,
    ipaddr: '192.168.0.120',
    port: 51211,
    status: 2,
    autoreconnect: true,
    usessl: true } ]

===== Device Menu =====

(1) Set connection mode
(2) Enable SSL
(3) Disable SSL
(4) Disconnect
(5) Disconnect All
(6) Refresh the device list
(q) Return to Main Menu

>>>>> Select a menu: 2

Enter the device IDs to enable SSL
Enter the device ID (Press just ENTER if no more device): 544142231
Enter the device ID (Press just ENTER if no more device):

To change these options, you have to connect to the devices first using menu (2) ~ (4).

2. Synchronous connections

You can use the Synchronous APIs to manage the connections by yourself.

function connectToDevice(addr, port, useSSL) {
  var connInfo = new connectMessage.ConnectInfo();
  connInfo.setIpaddr(addr);
  connInfo.setPort(port);
  connInfo.setUsessl(useSSL);

  var req = new connectMessage.ConnectRequest();
  req.setConnectinfo(connInfo);

  return new Promise((resolve, reject) => {
    connect.getClient().connect(req, (err, response) => {
      resolve(response.getDeviceid());
    });
  });
}

function disconnect(deviceIDs) {
  var req = new connectMessage.DisconnectRequest();
  req.setDeviceidsList(deviceIDs);

  return new Promise((resolve, reject) => {
    connect.getClient().disconnect(req, (err, response) => {
      resolve(response);
    });
  });
}

var devID = await connect.connectToDevice(connInfo.getIpaddr(), connInfo.getPort(), connInfo.getUsessl());

// do something with the devID

await connect.disconnect(deviceIDs);

3. Asynchronous connections

With the Asynchronous APIs, you only have to register or deregister devices. The gateway will handle all the connection related tasks in the background.

function addAsyncConnection(connInfos) {
  var req = new connectMessage.AddAsyncConnectionRequest();
  req.setConnectinfosList(connInfos);

  return new Promise((resolve, reject) => {
    connect.getClient().addAsyncConnection(req, (err, response) => {
      resolve(response);
    });
  });
}

function deleteAsyncConnection(deviceIDs) {
  var req = new connectMessage.DeleteAsyncConnectionRequest();
  req.setDeviceidsList(deviceIDs);

  return new Promise((resolve, reject) => {
    connect.getClient().deleteAsyncConnection(req, (err, response) => {
      resolve(response);
    });
  });
}

You have to use Connect.GetDeviceList to get the status of the registered devices.

async function showAsyncConnection() {
  var connInfos = [];

  try {
    var devList = await connect.getDeviceList();

    for(let i = 0; i < devList.length; i++) {
      if(devList[i].autoreconnect) {
        connInfos.push(devList[i]);
      }
    }

    console.log(`\n***** Async connections: ${connInfos.length}`);
    console.log(connInfos);

    return connInfos;
  }  catch (err) {
    console.error('Cannot get the async connections: ', err);
    return null;
  }
}

4. Accept devices

function getAcceptFilter() {
  var req = new connectMessage.GetAcceptFilterRequest();

  return new Promise((resolve, reject) => {
    connect.getClient().getAcceptFilter(req, (err, response) => {
      resolve(response.toObject().filter);
    })
  })
}

function setAcceptFilter(filter) {
  var req = new connectMessage.SetAcceptFilterRequest();
  req.setFilter(filter);

  return new Promise((resolve, reject) => {
    connect.getClient().setAcceptFilter(req, (err, response) => {
      resolve(response);
    })
  })
}

By default, the gateway will not accept any incoming connections. Connect.GetPendingList can be used to get the devices, which are trying to connect to the gateway but not in the accept filter.

function getPendingList() {
  var req = new connectMessage.GetPendingListRequest();

  return new Promise((resolve, reject) => {
    connect.getClient().getPendingList(req, (err, response) => {
      resolve(response.toObject().deviceinfosList);
    });
  });
}

You can allow all the incoming connections by setting AcceptFilter.allowAll to true. Or, you can specify the devices to be allowed in AcceptFilter.deviceIDs.

async function allowAll() {
  try {
    var filter = new connect.connectMessage.AcceptFilter();
    filter.setAllowall(true);
    filter.setDeviceidsList([]);

    await connect.setAcceptFilter(filter);
  } catch (err) {
    console.error('Cannot allow all devices: ', err);
  }
}

async function addDevicesToFilter() {
  var deviceIDs = menu.getDeviceIDs();

  try {
    var oldFilter = await connect.getAcceptFilter();

    var newFilter = new connect.connectMessage.AcceptFilter();
    newFilter.setAllowall(false);
    
    var newDeviceIDs = oldFilter.deviceidsList;

    for(let i = 0; i < deviceIDs.length; i++) {
      let exist = false;

      for(let j = 0; j < newDeviceIDs.length; j++) {
        if(deviceIDs[i] == newDeviceIDs[j]) {
          exist = true;
          break;
        }
      }

      if(!exist) {
        newDeviceIDs.push(deviceIDs[i]);
      }
    }
    
    newFilter.setDeviceidsList(newDeviceIDs);

    await connect.setAcceptFilter(newFilter);
  } catch (err) {
    console.error('Cannot add devices to the filter: ', err);
  }
}

5. Connection status

Apart from Connect.GetDeviceList, you can also get the realtime update using Connect.SubscribeStatus.

function subscribe(queueSize) {
  var req = new connectMessage.SubscribeStatusRequest();
  req.setQueuesize(queueSize);

  return connClient.subscribeStatus(req);
}

  var sub = connect.subscribe(QUEUE_SIZE);

  sub.on('data', (status) => {
    var devStatus = status.getStatus();

    switch(devStatus) {
      case connect.connectMessage.Status.DISCONNECTED:
        console.log('\n[Disconnected]: ', status.toObject());
        break;

      case connect.connectMessage.Status.TCP_CONNECTED:
        console.log('\n[TCP Connected]: ', status.toObject());
        break;

      case connect.connectMessage.Status.TLS_CONNECTED:
        console.log('\n[TLS Connected]: ', status.toObject());
        break;
    }
  });

  sub.on('end', () => {
    console.log('Subscription is finished');
  });

  sub.on('error', (err) => {
    console.log('Subscription error: ', err);
  })

6. Connection mode

function setConnectionMode(deviceIDs, mode) {
  var req = new connectMessage.SetConnectionModeMultiRequest();
  req.setDeviceidsList(deviceIDs);
  req.setConnectionmode(mode);

  return new Promise((resolve, reject) => {
    connect.getClient().setConnectionModeMulti(req, (err, response) => {
      resolve(response);
    });
  });
}

After setting the connection mode, you have to use different APIs accordingly. With SERVER_TO_DEVICE, you should use the Synchronous APIs or the Asynchronous APIs. to connect to the devices. With DEVICE_TO_SERVER, the AcceptFilter should be configured correctly.

7. SSL

TLS 1.2 can be used for more secure communication between the gateway and devices. Refer to Secure Communication for details.

function enableSSL(deviceIDs) {
  var req = new connectMessage.EnableSSLMultiRequest();
  req.setDeviceidsList(deviceIDs);

  return new Promise((resolve, reject) => {
    connect.getClient().enableSSLMulti(req, (err, response) => {
      resolve(response);
    });
  });
}


function disableSSL(deviceIDs) {
  var req = new connectMessage.DisableSSLMultiRequest();
  req.setDeviceidsList(deviceIDs);

  return new Promise((resolve, reject) => {
    connect.getClient().disableSSLMulti(req, (err, response) => {
      resolve(response);
    });
  });
}