I can register a specical period callback in OnBar, so which interface I shall call? is it context.subscribeToBarsFeed? If yes, how to set the fourth parameter: listener IBarFeedListener listener?
thanks a log, a sample will be good.

To process standard chart with specific period please use this:

    public void onBar(Instrument instrument, Period period, IBar askBar, IBar bidBar) throws JFException {
        if(!instrument.equals(Instrument.EURUSD) || !period.equals(Period.ONE_HOUR)) {
            return;
        }
        
        // do the work
    }

If the strategy needs custom feed, renko or range bars for instance, then the strategy needs to subscribe to the custom feed as described here:
https://www.dukascopy.com/wiki/#Chart_f ... _to_a_feed