ApplicationServer server

This instance's owning server.

Reference back to the owning server that adds requests into this sink.

Source 

ApplicationServer get server => _server;
void server=(ApplicationServer server)

Source 

set server(ApplicationServer server) {
  _server = server;
  messageHub._outboundController.stream.listen(server.sendApplicationEvent);
  server.hubSink = messageHub._inboundController.sink;
}