{
  "rules": {
    "messages": {
      ".read": true,
      // Users can only write messages if they are authenticated.
      ".write": "auth !== null",
      "$messageId": {
        // The name has to be the real display name.
        ".validate": "newData.child('name').val() === auth.token.name",
        "text": {
          // The text has to be less than 300 char.
          ".validate": "newData.isString() && newData.val().length < 300"
        }
      }
    },
    "fcmTokens": {
      // User can write their tokens to the database but not read the list of tokens.
      ".read": false,
      ".write": true
    }
  }
}