Azure IoT Hub

Overview

IoT Hub is a managed service, hosted in the cloud, that acts as a central message hub for bi-directional communication between your IoT application and the devices it manages. You can use Azure IoT Hub to build IoT solutions with reliable and secure communications between millions of IoT devices and a cloud-hosted solution backend. You can connect virtually any device to IoT Hub.

At a glance

Features

• Native Delphi implementation with full ANSI/Unicode support.

Technical specification

Main properties

The principal published / public properties used to configure and drive the component. Consult the online help for the full list.

Main methods

The principal public methods exposed by the component.

Quick Start

Drop the component on a form, configure the properties below and activate it. The snippet that follows shows the typical Connect to Azure IoT Hub configuration sourced from the online help.

Delphi (VCL / FireMonkey)

oClient := TsgcIoTAzure_MQTT_Client.Create(nil);
oClient.Azure.IoTHub := 'youriothub.azure-devices.net';
oClient.Azure.DeviceId := 'YourDeviceId';
oClient.SAS.Enabled := True;
oClient.SAS.SecretKey := 'YourSecretKey';
oClient.OnMQTTConnect := OnMQTTConnectEvent;
oClient.Active := True;
 
procedure OnMQTTConnect(Connection: TsgcWSConnection; const Session: Boolean; const
ReturnCode: TmqttConnReturnCode);
begin
  ShowMessage('Connected to Azure IoT Hub');
end;

C++ Builder

TsgcIoTAzure_MQTT_Client *oClient = new TsgcIoTAzure_MQTT_Client();
oClient->Azure->IoTHub = "youriothub.azure-devices.net";
oClient->Azure->DeviceId = "YourDeviceId";
oClient->SAS->Enabled = true;
oClient->SAS->SecretKey = "YourSecretKey";
oClient->OnMQTTConnect = OnMQTTConnectEvent;
oClient->Active = true;
 
private void OnMQTTConnect(TsgcWSConnection *Connection, const bool Session, const TmqttConnReturnCode *ReturnCode)
{
  ShowMessage("Connected to Azure IoT Hub");
}

Common scenarios

The following scenarios are lifted verbatim from the online help. Each shows the configuration and method calls needed to drive the component through a specific real-world flow.

1 · Device Provisioning Service

Azure IoT allows you to register devices from code using DPS. Currently, the library supports registering a device passing the Scope Id and Registration Id as parameters.

oClient := TsgcIoTAzure_MQTT_Client.Create(nil);
Try
  oClient.Certificate.CertFile := 'cert.pem';
  oClient.Certificate.KeyFile := 'key.pem';
  oClient.Certificate.Enabled := True;
  oResponse := TsgcIoT_Azure_OperationRegistrationState.Create;
  Try
    if oClient.ProvisioningDeviceClient_Register('scope_id', 'registration_id', oResponse) then
      ShowMessage('#Provisioning Register OK: ' + oResponse.Status)
    else
      ShowMessage('#Provisioning Register Error: ' + oResponse.Status);
  Finally
    FreeAndNil(oResponse);
  End;
Finally
  FreeAndNil(oClient);
End;

TsgcIoTAzure_MQTT_Client* oClient = new TsgcIoTAzure_MQTT_Client(NULL);
try
{
    oClient->Certificate->CertFile = L"cert.pem";
    oClient->Certificate->KeyFile = L"key.pem";
    oClient->Certificate->Enabled = true;
    TsgcIoT_Azure_OperationRegistrationState* oResponse = new TsgcIoT_Azure_OperationRegistrationState();
    try
    {
        if (oClient->ProvisioningDeviceClient_Register(L"scope_id", L"registration_id", oResponse))
            ShowMessage(L"#Provisioning Register OK: " + oResponse->Status);
        else
            ShowMessage(L"#Provisioning Register Error: " + oResponse->Status);
    }
    __finally
    {
        delete oResponse;
    }
}
__finally
{
    delete oClient;
}

TsgcIoTAzure_MQTT_Client oClient = new TsgcIoTAzure_MQTT_Client();
oClient.Certificate.CertFile = "cert.pem";
oClient.Certificate.KeyFile = "key.pem";
oClient.Certificate.Enabled = true;
TsgcIoT_Azure_OperationRegistrationState oResponse = new TsgcIoT_Azure_OperationRegistrationState();
if (oClient.ProvisioningDeviceClient_Register("scope_id", "registration_id", oResponse))
  MessageBox.Show("#Provisioning Register OK: " + oResponse.Status);
else
  MessageBox.Show("#Provisioning Register Error: " + oResponse.Status);

2 · Upload Files

IoT hub facilitates file uploads from connected devices by providing them with shared access signature (SAS) URIs or X509 certificates.

procedure UploadFileToAzure;
begin
  oDialog := TOpenDialog.Create(nil);
  Try
    if oDialog.Execute then
      AzureIoT.UploadFile(oDialog.FileName);
  Finally
    oDialog.Free;
  End;
end;

void UploadFileToAzure()
{
    TOpenDialog* oDialog = new TOpenDialog(NULL);
    try
    {
        if (oDialog->Execute())
        {
            AnsiString fileName = oDialog->FileName;
            AzureIoT::UploadFile(fileName.c_str());
        }
    }
    __finally
    {
        oDialog->Free();
    }
}

void UploadFileToAzure()
{
  TOpenDialog oDialog = new TOpenDialog();
  if (oDialog.Execute())
  {
    AzureIoT.UploadFile(oDialog.FileName);
  }
}

3 · Cloud To Device

IoT Hub provides three options for device apps to expose functionality to a back-end app:

oClient.Subscribe_DirectMethod;

oClient->Subscribe_DirectMethod();

4 · Device To Cloud

When sending information from the device app to the solution back end, IoT Hub exposes the following options:

oClient.Send_DeviceToCloud('{"temp": 10}', azuIoTQoS1);

oClient->Send_DeviceToCloud("{\"temp\": 10}", azuIoTQoS1);

Sources used to build this document

Every external claim links back to a primary source. The online-help references decode the canonical deep-link the company maintains for this component.