IEEE Consumer Electronics Magazine - November/December 2021 - 72

Special Section on Advances in Smart Cities
Figure 3. Weather service integrated as virtual
device.
the data provided by the weather service, this
service is represented as the virtual sensor
within the smart home system.
The flow of virtual device integration is presented
in Figure 3. The user is responsible for
external service activation, i.e., the initiation of
the integration process. For weather forecast,
this process requires providing the address of
the household. When the user enables the service,
the virtual weather device is created on
their hub, and the geographical location of the
hub is stored by the weather service adapter in
the smart home cloud.
To enable weather data retrieval, the smart
home cloud should identify itself as the authorized
consumer of the external service HTTP
API, by providing the registered application key.
Depending on the particular case, the users may
also need to authorize the smart home cloud to
receive personalized information from the external
service, i.e., they could allow linking of the
accounts they use within the smart home system
and the external service. This would be required
for various maintenance and utility services.
Once the cloud level authorization is performed,
the service adapter in the smart home
cloud requests information from the external
service, and converts it to the format that can be
exchanged with the smart home hub. The service
adapter also aims to optimize the communication
with the external service, and cache data
of interest in the Redis database. For example,
the weather service adapter polls the external
weather service for data periodically, in order to
ensure the freshness of the weather information
for the particular location. Once retrieved, the
updated information is sent to all of the hubs in
the same geographical area, using the dedicated
MQTT topic for that location (see Figure 3).
72
Figure 4. Camera platform integration through
device twin.
SURVEILLANCE PLATFORM
INTEGRATION
As an example of the external device platform,
we integrate the smart home with the
video surveillance solution15. The video surveillance
platform equips the supported cameras
with the firmware, which allows to control different
camera settings, to issue commands, and to
store recordings in the cloud. Also, the cameras
can create short video recordings when the
movement is detected in their area, and send
these snapshots to the cloud. All of the cameras
support Open Network Video Interface Forum
(ONVIF) protocol, and some of their functionalities
can be controlled through the local network.
However, to access the recordings, or react to
the detected movement events, the integration
with the video surveillance platform is needed.
To add the camera to their home system, the
user must first initiate the local network discovery
of the device, as they would with any camera
(see Figure 4). Based on the reported camera
properties, the smart home hub knows that the
camera in question is actually supported by the
external platform, and initiates the creation of
the camera twin in the smart home cloud. Using
OAuth 2.0, the user authorizes the smart home
cloud to connect with their surveillance platform
account, and the relevant functionalities of the
camera are exposed through the HTTPS API provided
by the video surveillance platform.
If possible, cameras are controlled through
ONVIF commands, issued in the local network.
For example, the zoom level, camera panning
and tilt can be controlled locally. However, if the
functionality is not supported locally, which is
the case with recording commands, the smart
IEEE Consumer Electronics Magazine
IEEE Consumer Electronics Magazine - November/December 2021

Table of Contents for the Digital Edition of IEEE Consumer Electronics Magazine - November/December 2021
