You should implement a simple REST API with Django REST Framework to synchronize remote mobile devices executing Tasks.

In your model you should represent the concept of a Customer, where each customer has:
- An email address
- A password

Each customer may posses zero or more Devices, where each device has:
- A unique UUID

For each customer there is a list of Tasks, where each Task has:
- An ID (INTEGER)
- A state (INTEGER)

Devices can execute Tasks. Devices can only execute tasks belonging to their owner. When a device starts executing a task, it has 2 minutes to complete it. Tasks can be retried an arbitrarily large amount of times. Devices have a mobile connectivity and may go offline at any time (may not be able to call any REST API).

The result of an execution of a Task by a Device can be:
- Success (in that case the Task is completed)
- Failure (the task should be re-executed)
- Execution Time Exceeded (the device did not complete in 2 minutes and the task should be re-executed)

The same Task can only be executed by one device at a time.
One Device can execute at most one Task at a Time.
Different Devices can execute different tasks concurrently.

Coding Questions
- Using Django Rest Framework, define the model that you suggest to use. Feel free to add new fields if you need it to correctly implement the synchronization algorithm
- Define the set of possible states of a Task
- Add an API method to let a Device retrieve the set of Tasks it may execute
- Add an API method to let a Device notify the beginning of the execution of a Task
- Add an API method to let a Device notify the result of an execution of a Task
- How would you suggest to configure permissions for the previous model (coding is NOT required)?

Question

You should implement a simple REST API with Django REST Framework to synchronize remote mobile devices executing Tasks.

In your model you should represent the concept of a Customer, where each customer has:
- An email address
- A password

Each customer may posses zero or more Devices, where each device has:
- A unique UUID

For each customer there is a list of Tasks, where each Task has:
- An ID (INTEGER)
- A state (INTEGER)

Devices can execute Tasks. Devices can only execute tasks belonging to their owner. When a device starts executing a task, it has 2 minutes to complete it. Tasks can be retried an arbitrarily large amount of times. Devices have a mobile connectivity and may go offline at any time (may not be able to call any REST API).

The result of an execution of a Task by a Device can be:
- Success (in that case the Task is completed)
- Failure (the task should be re-executed)
- Execution Time Exceeded (the device did not complete in 2 minutes and the task should be re-executed)

The same Task can only be executed by one device at a time.
One Device can execute at most one Task at a Time.
Different Devices can execute different tasks concurrently.

Coding Questions
- Using Django Rest Framework, define the model that you suggest to use. Feel free to add new fields if you need it to correctly implement the synchronization algorithm
- Define the set of possible states of a Task
- Add an API method to let a Device retrieve the set of Tasks it may execute
- Add an API method to let a Device notify the beginning of the execution of a Task
- Add an API method to let a Device notify the result of an execution of a Task
- How would you suggest to configure permissions for the previous model (coding is NOT required)?

Anoniem · Accepted Answer

Django project containing all the required tasks (including the permissions). Turned out to be the best project out of all candidates (that's what my recruiter told me).

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