email = request.getParameter("email");
name = request.getParameter("name");
if(email==null || "".equals(email.trim())){
throw new GameException("email is not provided");
}
if(name==null || "".equals(name.trim())){
throw new GameException("name is not provided");
}
user = engine.getUsers().get(getSessionId());
if(user!=null){
throw new GameException("user name is not null");
}
user = engine.getUser(email);
if(user!=null){
throw new GameException("this email is already in use now, try to login by another email");
}
}