To notify ofp_port state change, this patch implements ofp_event.EventOFPPortStateChange. This event performs like EventOFPPortStatus, but ofp_handler will send this event after updating "ports" dict of datapath instances. And, this patch suppresses the warning when user app accessing to datapath.ports for backward compatibility. Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>