in roscpp_azure_iothub/src/ros_azure_iothub_cpp_node.cpp [200:219]
void sendMsgToAzureIoTHub(const char* msg, IOTHUB_DEVICE_CLIENT_HANDLE deviceHandle)
{
static int messagecount;
// Construct the iothub message from a string or a byte array
IOTHUB_MESSAGE_HANDLE message_handle = IoTHubMessage_CreateFromString(msg);
// Set Message property
(void)IoTHubMessage_SetMessageId(message_handle, "MSG_ID");
(void)IoTHubMessage_SetCorrelationId(message_handle, "CORE_ID");
(void)IoTHubMessage_SetContentTypeSystemProperty(message_handle, "application%2fjson");
(void)IoTHubMessage_SetContentEncodingSystemProperty(message_handle, "utf-8");
ROS_INFO("Sending message %d to IoTHub\r\nMessage: %s", (int)(messagecount + 1), msg);
IoTHubDeviceClient_SendEventAsync(deviceHandle, message_handle, send_confirm_callback, NULL);
// The message is copied to the sdk so the we can destroy it
IoTHubMessage_Destroy(message_handle);
messagecount++;
}