We will begin with one of the more important features of a multiplayer game: the ability for players to establish themselves as a user, and communicate with one another.
Nakama helps us do this by making it easy to create a centralized server, where data is stored and processed, and allowing our players (clients) to connect to the server.
Establishing a connection #
Here we connect the Unity client and the Nakama server.
The first step is to register a new Client object upon game start in Unity. This object will be the interface for any interactions between the client and the server.
Below is the snippet from the Main Menu script that initializes the client:
Here, we’re creating a connection to the server that you started locally (available at
http://localhost:7350) by passing the following connection values:
Scheme: The connection scheme,
Host: The server host,
localhostfor this example.
Port: The server port, set to
ServerKey: By default
defaultkeyis used. Can be changed via the server configuration.
Device authentication #
After establishing the server connection, we authenticate the player so we can connect them to an identity.
When starting Pirate Panic, you may notice that you are automatically authenticated and assigned a username. This type of seamless authentication is device authentication, which creates accounts linked to the device that is running the game, such as a phone or computer.
In Unity, device authentication can be done by fetching the Device ID and passing it into
When authentication is complete, the player joins a session, which represents the period of time a player is logged in. See Sessions to learn more.
The session object allows us to make requests and access user information as an authenticated client, primarily through the
In Pirate Panic, the
session properties are saved in the
GameConnection object. So any access to
_connection later on, remember that it is referring to these properties.
Facebook authentication #
Device authentication makes it easy for players to jump right into the game, but linking accounts to devices means that if the device is ever lost or reset the account is lost. Connecting via an external social provider, such as Facebook, to user accounts enables you to mitigate this issue and fetch additional user information.
Include the Facebook SDK in the scene script and initialize it as follows:
Then, the following snippet handles the log in:
LinkFacebookto a Connect Facebook button so players can choose when to login rather than being forced to do so right away.
Here, we’re giving the
public_profile permission so that Nakama can access basic user information like name or profile picture. You can also add other permissions and features, which can be found in the Facebook SDK documentation.
Logging into Facebook will automatically add a player’s Facebook friends into their in-game friends list.
Initializing a new player #
After players have a way to log in, next is setting up the initial player information so they can start adding friends, collecting gems, completing quests, or anything else that requires storing user data over time.
This can be done on the server side using a register hook. There is a different hook for each authentication method. For example, since we set up device and Facebook authentication, we should use
We bind a function to them that runs when the hook is triggered:
Session tokens #
For security reasons, player sessions will automatically expire after the time period defined in your Nakama configuration. To avoid forcing players to constantly log back in, we can set up a method to automatically request a new session when the old one is about to expire.
This is done by saving tokens for authentication on the client, and periodically passing these back to the server to request new tokens.
There are two types of tokens:
- Access tokens: Tell the server about the identity of the client and allows the server to trust this client.
- Refresh tokens: Used to request new access tokens.
With Nakama, we can use the
client object to request new tokens with
Here, we use Unity’s built in
PlayerPrefs engine to store the access token and refresh token into
If the session is less than a day away from expiring, the script will attempt to request a new access token using
SessionRefreshAsync. If the refresh token is invalid, this will fail and we’ll need to re-authenticate all over again.