This page details the process of sending information between the frontend and Unity. Communication occurs via web sockets in a (roughly) event-based manner (somewhat like Socket.IO, but due to lacking a correct server implementation on the Unity-side of things we're using bare web sockets instead).
## Basics
Our implementation makes use of a simple serialization scheme following the pattern `className;payload`, where `className` can be any string and `payload` can be empty, a string or a string-serialized object (JSON).
In both backend and frontend corresponding listeners will be triggered based on the incoming message and the message payload will be delivered to the respective handlers.
## Unity
Currently (as in: subject to change once I get around to it), the backbone of the IPC (inter-process communication) on Unitys side is `WebsocketController`, which is first initialized in the `InitGlobals` in each scene.
### Setting callbacks
We can register callback functions to react to signals from the frontend using several functions (all of which are `static` methods of the `WebsocketController` class):
*`void SimpleCallback(string className, Action<string> callback)`: treats the payload of the incoming message as a bare string
*`void JsonCallback<T>(string className, Action<T> callback)`: automatically deserializes the payload based on the type parameter `T` for the callback.
### Sending messages
To send new information to the frontend, `WebsocketController` defines some further static methods:
*`void Respond(string className, JsonData data)` sends a serialized object where `JsonData` is the base type that has to be extended by the data class
*`void SendMsg(string className, string msg)` sends a raw string to the respective message class for the frontend to react to.
### Implemented Messages (may be non-exhaustive)
Below is a list of messages that (at time of writing) can be used to relegate data to the classroom in Unity:
*`classChange`, payload: `string` serialized object of shape `{room: string, front: string, outside: string, chairs: string, students: Number, messiness: Number, weather: WeatherPattern}`, where all of these fields may be optional
*`bootstrap`, payload: none. Request for Unity to send initial classroom info
*`behave`, payload: `{students: string[], behaviour: string}`. List of students and a behaviour to apply to them
*`askQuestion`, payload: `{students: string[], questions: Number[]}`. List of students and corresponding question ids
*`impulseGiven`, payload: `{students: string[], impulse: string}`. List of students to trigger impulse for
