Dear Support,

I got stuck here please help! I'm going to write a strategy based on the 70 tick bars using the following piece of code below:

 int tickBarSize= 70 ;
   
   .....................................................................................................................................
    context.subscribeToTickBarFeed(Instrument.EURUSD, OfferSide.BID,  TickBarSize.valueOf(tickBarSize), new ITickBarFeedListener() {
            @Override
            public void onBar(Instrument instrument, OfferSide offerSide, TickBarSize size, ITickBar bar) {
                            
                double[] heikin = indicators.heikinAshi(instrument, period, OfferSide.BID, 1);  // what period ????
                ...................................................................................................... 
            }
        });

My question is: how to use the time based indicator indicators.heikinAshi within the ITickBarFeedListener here ? What value should I give for the indicators.heikinAshi's "Period" parameter?

Thank you in advance!

See the example:
https://www.dukascopy.com/wiki/#Chart_feeds/Feed_history,_indicator_calculation_and_chart_opening
For more on indicator calculation on a feed, see:
https://www.dukascopy.com/wiki/#Indicator_Calculation/Universal_price_feed

Thanks Support for the prompt answer! After reading the links I understood that I have to calculate the heikinAshi indicator with the following function below:

Object[] heikin= indicators.calculateIndicator(feedDescriptor, new OfferSide[] { OfferSide.BID }, "heikinAshi", new AppliedPrice[] { AppliedPrice.CLOSE }, null, dataCount, feedData.getTime(), 0);

but how can I get the "IFeedDescriptor feedDescriptor" and feedData.getTime() variables from within the context.subscribeToTickBarFeed function?

Could you please give an example? I don't really understand the connection between ITickBarFeedListener and IFeedDescriptor here.

Thanks in advance!

You need to use IContext.subscribeToFeed, consider modifying our given wiki example to use the heikin ashi indicator:

public class TickBarsHeikinAshi implements IStrategy, IFeedListener {

    private IConsole console;
    private IIndicators indicators;

    @Configurable(value = "feed type", description = "choose any type of feed (except ticks) in the strategy parameters dialog")
    public IFeedDescriptor feedDescriptor = new TickBarFeedDescriptor(Instrument.EURUSD, TickBarSize.valueOf(70), OfferSide.BID);

    @Override
    public void onStart(IContext context) throws JFException {

        console = context.getConsole();
        indicators = context.getIndicators();

        if (feedDescriptor.getDataType() == DataType.TICKS) {
            console.getErr().println("IFeedListener does not work with ticks yet!");
            context.stop();
        }

        context.setSubscribedInstruments(new HashSet<Instrument>(Arrays.asList(new Instrument[] { feedDescriptor.getInstrument() })), true);

        console.getOut().println("subscribe to feed=" + feedDescriptor);
        context.subscribeToFeed(feedDescriptor, this);

    }

    @Override
    public void onFeedData(IFeedDescriptor feedDescriptor, ITimedData feedData) {
        console.getInfo().println(feedData + " of feed: " + feedDescriptor);
        try {
            double[] c = (double[]) indicators.calculateIndicator(feedDescriptor, new OfferSide[] { OfferSide.BID }, "HeikinAshi",
                    new AppliedPrice[] { AppliedPrice.CLOSE }, null, 1)[0];
            console.getOut().format("%s ha O: %.5f H: %.5f L: %.5f C: %.5f ", DateUtils.format(feedData.getTime()), c[OPEN], c[HIGH], c[LOW], c[CLOSE]).println();
        } catch (JFException e) {
            console.getErr().println(e);
            e.printStackTrace();
        }
    }

There is no connection between those two rather IFeedListener is a generalization of ITickBarFeedListener and IFeedDescriptor correspondingly of TickBarFeedDescriptor. Using more general methods gives you more flexibility in adjusting the strategy when the business logic changes - for instance, in the given example you may switch to using 1-minute candles or, say, renko bricks simply by changing the feed descriptor parameter in the strategy dialog, without any additional coding required.