Communication between Unity and the frontend

This page details the process of sending information between the frontend (coach vr) 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 (coach vr) 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
• themeChange, payload: {theme: string, skip: boolean, globalKnowledge: boolean}

Frontend (Coach VR)