The current socket API exhibits a temporal dependence:

$server = new Server($loop);
$server->listen(1234);
$server->getPort();
$server->on('connection', function () { });
$server->shutdown();

• What happens if you call listen() twice?
  It's tempting to think that this will allow you to listen on two addresses – it does not.
• What happens if you call shutdown() twice or before calling listen()?
  Errors out – should probably be ignored
• What happens if you call getPort() before calling listen() or after calling shutdown()?
  Errors out – should probably be ignored
• What happens if you call listen() after calling shutdown()?
  Should work, but makes for an awkward API.

Afaict most of this boils down to this:

• What does a Server instance actually represent?
  Honestly, I'm not sure how to answer this. Once listen() has been called, it represents a "server socket", but until then?

Afaict most of these issues can be avoided if a Server instance always were to represent a "server socket" (which is possibly in a closed state). This means that the listen call would have to be part of the construction.

One possible API could look like this:

$server = $api->createServer(1234);
$server->getPort();
$server->on('connection', function() { });
$server->shutdown();