You can connect to application server via SocketRelay:
$relay = new Spiral\Goridge\SocketRelay("127.0.0.1", 6001);
$rpc = new Spiral\Goridge\RPC($relay);
You can immediately use this RPC to call embedded RPC services such as HTTP:
var_dump($rpc->call('http.Workers', true));
See RPC method definition here.
You can read how to create your own services and RPC methods in this section.