- `upgradeTimeout` (`Number`): how many ms before an uncompleted transport upgrade is cancelled (`10000`)

- `maxHttpBufferSize` (`Number`): how many bytes or characters a message

can be, before closing the session (to avoid DoS). Default

- `allowRequest` (`Function`): A function that receives a given handshake

or upgrade request as its first parameter, and can decide whether to

continue or not. The second argument is a function that needs to be

this.pingTimeout = opts.pingTimeout || 5000;

this.pingInterval = opts.pingInterval || 25000;

this.upgradeTimeout = opts.upgradeTimeout || 10000;

this.transports = opts.transports || Object.keys(transports);

this.allowUpgrades = false !== opts.allowUpgrades;

this.allowRequest = opts.allowRequest;