Determine whether the user is present

[Annnnnieee]

The application needs to figure out whether the user is at the event or not.
It knows the dates and times when the user should be at an event, so it doesn't need to operate outside those times.

Considerations

• at what point can we be sure a user is present?
• How can the application distinguish between the user being present at the event vs not being present at the event, but near a few other people who are also supposed to attend?
• how many other event attendees need to be detected before the application decides that the user is present? (2? a percentage of the total?)
• how often should we check whether a user is present? (keep in mind that we can't always be precise in saying when a user actually arrived or left, but we can usually be sure that the user was there).
• how often should the user's device send messages? how can we make sure the devices in aggregate don't send too much traffic or create feedback loops?
• what data should be included in the message the device broadcasts? just the user id? maybe all the other user ids that the device has seen so far?
• how can this be implemented? are there chunks of functionality that can be broken into smaller classes?
• there are probably many more things to consider.

Done criteria

• the client sends a request to the server when a user is determined to be present
• the client sends a request to the server when a user is determined to be absent