1.login

@PostMapping loginRe(id, pw)

service.signIn(aop.SignControllerAspect) -> return String

if(id & !pw) = id_ok

if(id & pw) = all_ok

if(!id) = id_fail

2.join

@PostMapping save(user, nickname) <- One To One Table

service.signUp(aop.SignControllerAspect) -> not return

transaction will be add.... maybe