internal void OnConnOpen(object sender, EventArgs e)
{
Log("transport", $"connected to { EndpointUrl() }"); //FIX phoenix js doesnt need to build EndpointUrl more than once - added cache
FlushSendBuffer(); //jfis - send anythign buffered when conn opens
_reconnectTimer.Reset(); //jfis - stop bothering to try reconnecting
//skipHeartbeat only for longpoll
_heartbeatTimer.Stop(); //jfis - not sure this stop is necessary. can conn be opened while heartbeat enabled?
_heartbeatTimer.Start(); //jfis - connected now so begin sending heartbeats
foreach (var cb in _openCallbacks) cb();
}