class LoadBalancer implements IFloodlightModule,
    ILoadBalancerService, IOFMessageListener {

    @Override
    public LBPool createPool(LBPool pool) {
        if (pool == null)
            pool = new LBPool();
        
        pools.put(pool.id, pool);
        if (pool.vipId != null && vips.containsKey(pool.vipId))
            vips.get(pool.vipId).pools.add(pool.id);
        else {
            log.error("specified vip-id must exist");
            pool.vipId = null;
            pools.put(pool.id, pool);
        }
        return pool;
    }

}