Run the example

  1. Install and run the master gateway. Create the needed certificates as described in the Certificate Management.
  2. Install and run the device gateway. Configure the device gateway to connect to the master gateway as described in the Configuration.
  3. Download the Go client library
  4. Copy the certificates.
    • Copy the root certificate of the master gateway to your working directory. As default, the certificate(ca.crt) resides in cert of the installation directory of the master gateway.
    • Copy the administrator certificate and its private key to your working directory.
    • Copy the tenant certificate and its private key to your working directory.

  5. Change the gateway and certificate information in src/example/connectMaster/test/test.go as needed.

     // the path of the root certificate
 MASTER_CA_FILE = "../../../../../cert/master/ca.crt"

 // the address of the master gateway
 MASTER_IP = "192.168.0.2"
 MASTER_PORT = 4010

 // the paths of the administrator certificate and its key    
 ADMIN_CERT_FILE = "../../../../../cert/master/admin.crt"
 ADMIN_KEY_FILE = "../../../../../cert/master/admin_key.pem"

 // the paths of the tenant certificate and its key    
 TENANT_CERT_FILE = "../../../../../cert/master/tenant1.crt"
 TENANT_KEY_FILE = "../../../../../cert/master/tenant1_key.pem"    

 // the following values should be same as the IDs in the corresponding certificates
 TENANT_ID = "tenant1"
 GATEWAY_ID = "gateway1"

  6. Build.

     cd src/example/connectMaster/test
 go build .

  7. Run.

     ./test

    To initialize the database, you have to run with -i option once. See initMaster() for initializing the database.

1. CLI

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

$ ./test

===== 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 ConnectMaster.SearchDevice, you can get these information in a subnet.

>>>>> Select a menu: 1
Searching devices in the subnet...

***** Found 8 devices
deviceID:544114231 type:BIOENTRY_W2 useDHCP:true IPAddr:"192.168.0.104" port:51211
deviceID:540092578 type:BIOSTATION_L2 useDHCP:true IPAddr:"192.168.0.120" port:51211 useSSL:true
deviceID:846 type:BIOLITE_N2 useDHCP:true IPAddr:"192.168.0.117" port:51211
deviceID:939342898 type:BIOSTATION_A2 useDHCP:true connectionMode:DEVICE_TO_SERVER IPAddr:"192.168.0.121" port:51211 useSSL:true
deviceID:939504224 type:BIOSTATION_A2 useDHCP:true IPAddr:"192.168.0.110" port:51211
deviceID:939342902 type:BIOSTATION_A2 useDHCP:true IPAddr:"192.168.0.125" port:51211 useSSL:true
deviceID:542190033 type:FACESTATION_2 useDHCP:true IPAddr:"192.168.0.123" port:51211
deviceID:547634480 type:BIOSTATION_2 useDHCP:true IPAddr:"192.168.0.106" port:51211

(2) Connect to a device synchronously

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

(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 IPAddr:"192.168.0.120" port:51211 autoReconnect:true useSSL:true
deviceID:939504224 IPAddr:"192.168.0.110" port:51211 autoReconnect:true

(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 ConnectMaster.SetConnectionMode.
  2. By default, the gateway will not accept any incoming connections. You have to add the devices to the accept filter using ConnectMaster.SetAcceptFilter.
>>>>> Select a menu: 4

***** Accept filter:

***** Pending devices: 1
deviceID:939342898 IPAddr:"192.168.0.121" lastTry:1582762543

===== 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
Allowing all devices...

***** Accept filter: allowAll:true

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

>>>>> Select a menu: 5

***** Managed devices: 4
deviceID:544114231 IPAddr:"192.168.0.104" port:51211 status:TCP_CONNECTED
deviceID:540092578 IPAddr:"192.168.0.120" port:51211 status:TLS_CONNECTED autoReconnect:true useSSL:true
deviceID:939504224 IPAddr:"192.168.0.110" port:51211 status:TCP_CONNECTED autoReconnect:true
deviceID:939342898 connectionMode:DEVICE_TO_SERVER IPAddr:"192.168.0.121" status:TLS_CONNECTED 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): 54414231
>> 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.

func (s *ConnectMasterSvc) Connect(gatewayID string, deviceIP string, devicePort int, useSSL bool) (uint32, error) {
  req := &connectMaster.ConnectRequest{
    GatewayID: gatewayID,
    ConnectInfo: &connect.ConnectInfo{
      IPAddr: deviceIP,
      Port: int32(devicePort),
      UseSSL: useSSL,
    },
  }

  resp, _ := s.client.Connect(context.Background(), req)

  return resp.GetDeviceID(), nil
}

func (s *ConnectMasterSvc) Disconnect(deviceIDs []uint32) error {
  req := &connectMaster.DisconnectRequest{
    DeviceIDs: deviceIDs,
  }

  s.client.Disconnect(context.Background(), req)

  return nil
}

devID, err := connectMasterSvc.Connect(gatewayID, connInfo.IPAddr, int(connInfo.Port), connInfo.UseSSL)

// do something with the devID

connectMasterSvc.Disconnect([]uint32{ devID })

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.

func (s *ConnectMasterSvc) AddAsyncConnection(gatewayID string, connInfos []*connect.AsyncConnectInfo) error {
  req := &connectMaster.AddAsyncConnectionRequest{
    GatewayID: gatewayID,
    ConnectInfos: connInfos,
  }

  s.client.AddAsyncConnection(context.Background(), req)

  return nil
}

func (s *ConnectMasterSvc) DeleteAsyncConnection(gatewayID string, deviceIDs []uint32) error {
  req := &connectMaster.DeleteAsyncConnectionRequest{
    GatewayID: gatewayID,
    DeviceIDs: deviceIDs,
  }

  s.client.DeleteAsyncConnection(context.Background(), req)

  return nil
}

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

func showAsyncConnection() error {
  devList, _ := connectMasterSvc.GetDeviceList(gatewayID)

  asyncList := []*connect.DeviceInfo{}

  for _, device := range devList {
    if device.AutoReconnect {
      asyncList = append(asyncList, device)
    }
  }

  fmt.Printf("\n***** Async connections: %v\n", len(asyncList))

  for _, device := range asyncList {
    fmt.Printf("%v\n", device)
  }

  return nil
}

4. Accept devices

func (s *ConnectMasterSvc) GetAcceptFilter(gatewayID string) (*connect.AcceptFilter, error) {
  req := &connectMaster.GetAcceptFilterRequest{
    GatewayID: gatewayID,
  }

  resp, _ := s.client.GetAcceptFilter(context.Background(), req)

  return resp.GetFilter(), nil
}


func (s *ConnectMasterSvc) SetAcceptFilter(gatewayID string, filter *connect.AcceptFilter) error {
  req := &connectMaster.SetAcceptFilterRequest{
    GatewayID: gatewayID,
    Filter: filter,
  }

  s.client.SetAcceptFilter(context.Background(), req)

  return nil
}

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

func (s *ConnectMasterSvc) GetPendingList(gatewayID string) ([]*connect.PendingDeviceInfo, error) {
  req := &connectMaster.GetPendingListRequest{
    GatewayID: gatewayID,
  }

  resp, _ := s.client.GetPendingList(context.Background(), req)

  return resp.GetDeviceInfos(), nil
}

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.

func allowAllDevices() error {
  filter := &connect.AcceptFilter{
    AllowAll: true,
    DeviceIDs: []uint32{},
  }

  connectMasterSvc.SetAcceptFilter(filter)

  return nil		
}

func (s *ConnectMasterSvc) AddDeviceToAcceptFilter(gatewayID string, deviceIDs []uint32) error {
  getReq := &connectMaster.GetAcceptFilterRequest{
    GatewayID: gatewayID,
  }

  getResp, _ := s.client.GetAcceptFilter(context.Background(), getReq)

  filter := getResp.GetFilter()
  filter.AllowAll = false

  for _, deviceID := range deviceIDs {
    exist := false;

    for i := 0; i < len(filter.DeviceIDs); i++ {
      if filter.DeviceIDs[i] == deviceID {
        exist = true;
        break
      }
    }

    if !exist {
      filter.DeviceIDs = append(filter.DeviceIDs, deviceID)
    }
  }

  setReq := &connectMaster.SetAcceptFilterRequest{
    GatewayID: gatewayID,
    Filter: filter,
  }

  s.client.SetAcceptFilter(context.Background(), setReq)

  return nil
}

5. Connection status

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

func (s *ConnectMasterSvc) Subscribe() (connectMaster.ConnectMaster_SubscribeStatusClient, context.CancelFunc, error) {
  ctx, cancel := context.WithCancel(context.Background())

  req := &connectMaster.SubscribeStatusRequest{
    QueueSize: QUEUE_SIZE,
  }

  statusStream, _ := s.client.SubscribeStatus(ctx, req)

  return statusStream, cancel, nil
}

  statusStream, cancelFunc, _ := connectMasterSvc.Subscribe()
  defer cancelFunc()

  go func(statusStream connectMasterService.ConnectMaster_SubscribeStatusClient) {
    for {
      statusChange, err := statusStream.Recv()

      if err != nil {
        fmt.Printf("Cannot get device status: %v", err)
        return
      }      

      // do something with statusChange
    }
  } (statusStream)

6. Connection mode

func (s *ConnectMasterSvc) SetConnectionModeMulti(deviceIDs []uint32, mode connect.ConnectionMode) error {
  req := &connectMaster.SetConnectionModeMultiRequest{
    DeviceIDs:      deviceIDs,
    ConnectionMode: mode,
  }

  s.client.SetConnectionModeMulti(context.Background(), req)

  return nil
}

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.

func (s *ConnectMasterSvc) EnableSSL(deviceIDs []uint32) error {
  req := &connectMaster.EnableSSLMultiRequest{
    DeviceIDs:      deviceIDs,
  }

  s.client.EnableSSLMulti(context.Background(), req)

  return nil
}


func (s *ConnectMasterSvc) DisableSSL(deviceIDs []uint32) error {
  req := &connectMaster.DisableSSLMultiRequest{
    DeviceIDs:      deviceIDs,
  }

  s.client.DisableSSLMulti(context.Background(), req)

  return nil
}

Updated: