Structure

General Structure

Empirica allows you to build powerful apps for multiplayer and singleplayer research. It is made of these important components:
  • Your code.
    • The backend (managing your games and data) with Meteor
    • The frontend (what the players see and interact with) with React.js
  • An Admin Panel that allows you manage the conditions, games, and players in your experiment.
  • A connection to a database, such as MongoDB Atlas, to store your data that can be accessed and modified live by your experiment.
  • The app is deployed to a hosting service, such as Meteor Galaxy, so that your experiment is online and you can send a link for players to connect to it.

File Structure

This is what a starting Empirica experiment file structure looks like:
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my-experiment
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β”œβ”€β”€ .meteor
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β”œβ”€β”€ README.md
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β”œβ”€β”€ node_modules
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β”œβ”€β”€ package.json
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β”œβ”€β”€ package-lock.json
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β”œβ”€β”€ .gitignore
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β”œβ”€β”€ public
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β”œβ”€β”€ client
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β”‚ β”œβ”€β”€ main.html
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β”‚ β”œβ”€β”€ main.js
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β”‚ β”œβ”€β”€ main.css
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β”‚ β”œβ”€β”€ game
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β”‚ β”‚ └── ...
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β”‚ β”œβ”€β”€ intro
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β”‚ β”‚ └── ...
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β”‚ └── exit
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β”‚ └── ...
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└── server
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β”œβ”€β”€ main.js
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β”œβ”€β”€ callbacks.js
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└── bots.js
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It contains:
  • .meteor with the meteor files. You do not need to touch those.
  • node_modules the files for the node modules in your app. You do not need to touch those. This directory should be in the .gitignore file.
  • public where you store static assets (e.g., images).
  • client where you set what the players can see in the experiment.
  • server where you manage the flow and resources of the experiment.

Client

All code in the /client directory will be ran on the client. The entry point for your app on the client can be found in /client/main.js. In there you will find more details about how to customize how a game Round should be rendered, what Consent message and which Intro Steps you want to present the players with, etc.
The HTML root of you app in /client/main.html shouldn't generally be changed much, other than to update the app's HTML <head>, which contains the app's title, and possibly 3rd party JS and CSS imports.
All styling starts in /client/main.less, and is written in LESS, a simple superset of CSS. You can also add a plain CSS files in /client.
The /client/game, /client/intro, /client/exit directories all contain React components, which compose the UI of your app. If you are new to React, we recommend you try out the official React Tutorial.

Server

Server-side code all starts in the /server/main.js file. In that file, we set an important Empirica integration point, the Empirica.gameInit, which allows to configure each game as they are initiated by Empirica.
From there we import 2 other files. First the /server/callback.js file, which contains all the possible callbacks used in the lifecycle of a game. These callbacks, such as onRoundEnd, offer powerful ways to add logic to a game in a central point (the server), which is often preferable to adding all the logic on the client.
Finally, the /server/bots.js file is where you can add bot definitions to your app.

Public

The /public is here to host any static assets you might need in the game, such as images. For example, if you add an image at /public/my-logo.jpeg, it will be available in the app at http://localhost:3000/my-logo.jpeg.
Last modified 8mo ago