ErnieApp interview questions

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)?