Django

Django#

The Django server hosts the REST API, manages the database, and provides a web interface for data visualization and user management. This server acts as the backend infrastructure that supports the entire IoT ecosystem by:

  • REST API: Facilitates communication between the IoT devices and the server. The API endpoints handle requests for data uploads from devices, send control commands, and provide access to stored telemetry data.

  • Database Management: Stores all the telemetry data, device information, user accounts, and configuration settings. The database ensures that data is organized, searchable, and retrievable in an efficient manner.

  • Web Interface: Offers a user-friendly interface for data visualization and management. Through this interface, users can monitor device status, visualize telemetry data in real-time, manage user accounts, and configure device settings.

Build and Run#

The Django server can also run locally, without the need of a docker container. Make sure to create a virtual environment and install the requirements:

host:~$ source venv/bin/activate
host:~$ cd workspace/flownexus/server/django
host:~/workspace/flownexus/server/django$ pip install -r requirements.txt
host:~/workspace/flownexus/server/django$ ./django_start.sh

The Django server should now be up and running under the following URL: http://localhost:8000/admin. The admin login is admin and the password

Run Unit Tests#

There are unit tests, that test the deserializer, which parses the Json payload from the ReST API. You can run the unit tests with the following command:

host:~/workspace/flownexus/server/django$ python manage.py test sensordata
Found 2 test(s).
Creating test database for alias 'default'...
----------------------------------------------------------------------
Ran 2 tests in 0.008s

OK
Destroying test database for alias 'default'...

Database Model#

The database model is the core of the Django server. It aims to store information according to the LwM2M resource model. The advantage is that data can be stored in a generic way and the server can be extended with new resources without changing the database schema.

The server application logic only has to handle higher level events. Those events are situations where multiple resources are associated (e.g. Temperature, Pressure, Humidity, Acceleration). Those multiple resources are linked in the event, together with a timestamp. The event itself is represented by the database model in a generic way, several custom event types can be created by the application logic.

An Entity Relationship Diagram (ERD) is a visual representation of the database schema. It is automatically generated from the Django models. sensordata is the Django app that contains the application logic.

../_images/erd.svg

Entity Relationship Diagram generated from Django models#

Endpoint#

IoT devices using the LwM2M protocol in the network, identifiable by a unique name, e.g. urn:imei:123456789012345.

ResourceType#

Defines resource data points comprehensively, annotating each with a unique object-resource ID combination, a descriptive name, and specifying the expected data type.

Resource#

A specific piece of data or functionality within an LwM2M Object. Resources represent attributes or actions and are identified by Resource IDs within an Object.

In the database Model a Resource represents an individual data value from one IoT device, annotated with timestamps, applicable data types, and linked to both the device and resource type for which the data is relevant.

Event#

A collection for significant occurrences reported by endpoints. Events and Resources are linked to each other via EventResource table.

EventResource#

Acts as a junction table forming a many-to-many relationship between events and their constituent resources, enabling flexible association without direct modification to the core events or resources tables.

EndpointOperation#

Represents actionable commands or processes targeted at endpoints, tracking the operation type, status, and scheduling through timestamps, also detailing the transmission attempts and last action.

Firmware#

Stores metadata about firmware binaries that are available for devices to download and install. Each record includes a version identifier, the name of the file, a URL from where the device can retrieve the firmware, and timestamps for tracking when each firmware record was created and last updated.

FirmwareUpdate#

keeps track of the execution of firmware updates for each endpoint. It adds references to the two required resources from server to endpoint (Send URI, execute Update). Furthermore it adds a field for the State and the Result of an update.