public synchronized ID addOnline(final USER user, final ID sessionId)
	{
		sessionIdToUser.put(sessionId, user);
		return usersOnline.put(user, sessionId);
	}
public synchronized ID addOnline ( final USER user , final ID sessionId ) { sessionIdToUser . put ( sessionId , user ) ; return usersOnline . put ( user , sessionId ) ; }
Adds the user online.

@param user
the user
@param sessionId
the session id
@return the string