Every generated tick will be written in a format "Average Price(Bid + (Bid + Ask)/2)" to a file with a timestamp based on a local PC time. The file name is being generated as Dukascopy_serverexpert + ForexPair +Year_Month_Day.csv.

package jforex;

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

import com.dukascopy.api.*;

@RequiresFullAccess
public class WriteTickToFile implements IStrategy {
   private IEngine engine;
   private IConsole console;
   private String FILE_NAME ;
   private SimpleDateFormat sdf;
   private SimpleDateFormat sdf2;

   @Configurable("Instrument")
   public Instrument selectedInstrument = Instrument.EURUSD;
   @Configurable("Directory")
   public String path = "C:\\temp\\";
   FileWriter fstream;
   BufferedWriter out;

   public void onStart(IContext context) throws JFException {
      Date date = new Date();
      this.engine = context.getEngine();
      this.console = context.getConsole();
      sdf = new SimpleDateFormat("yyyy.MM.dd");
      sdf2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
      FILE_NAME = path + "WriteTickToFile_" +  selectedInstrument.toString().replace("/", "") + "_" + sdf.format(date) +".csv";

      try {
         fstream = new FileWriter(FILE_NAME, true);
         out = new BufferedWriter(fstream);
      } catch (IOException e) {
         writeMessage("Can not initialize output stream; Stopping the strategy");
         context.stop();
      }
   }

   public void writeMessage(String message) {
      console.getOut().println(message);
   }

   public void onAccount(IAccount account) throws JFException {
   }

   public void onMessage(IMessage message) throws JFException {
   }

   public void onStop() throws JFException {
      try {
         if (out != null) {
            out.flush();
            out.close();
         }
      } catch (IOException e) {
         writeMessage("Can not close output stream");
         e.printStackTrace();
      }    
   }

   public void onTick(Instrument instrument, ITick tick) throws JFException {
      if (instrument.equals(selectedInstrument)) {
         try {
            out.append( sdf2.format(tick.getTime()) + ";" + ((tick.getAsk() + tick.getBid())/2) + "\n");
         } catch (IOException e) {
            writeMessage("File write error " );
            e.printStackTrace();
         }
      }
   }    

   public void onBar(Instrument instrument, Period period, IBar askBar, IBar bidBar) throws JFException {
      if (instrument.equals(selectedInstrument) && period.equals(Period.TEN_SECS)) {
         try {
            out.flush();
         } catch (IOException e) {
            writeMessage("Can not write message from the buffer to the file. Will retry in 1 minute.");
         }
      }
    } 
}

WriteTickToFile.java