EAServer must be started before apache proxy, otherwise, client will get (502 Bad gateway message) for the first call of httptunnel.
But the next call will be OK.
Looks like apache will try to connect to EAServer and it knows the state of EAServer when EAServer shuts down or EAServer does not startup. So for the first call, apache will use its connection to EAServer which is not available then. But for the next call, apache will create new connection to EAServer which will be OK!