Dukascopy Support Board • View topic

rmarco · **User rating:** -

Hello,

I noticed that, in certain conditions, I can introduce more than one order with the same Label.

I am running the strategy on a demo account through Java API (not JForex platform) in TEN_SECS period. I have two instances of the same strategy running, trying to introduce an order each new bar, with same Label. Almost every time both strategies are able to introduce the order, and I got a couple of orders with the same label.

Sometimes I get an "Order null rejected Order already being processed by the system." error, which I can't catch or treat in any way.

Thanks

API Support

Could you please provide an example code and a launch scenario for the case when when you manage to create two orders with the same label?
In a case you're only concerned about making your labels unique, you might consider the following method which ensures the label uniqueness between both of the strategies:

private String getLabel(String prefix){
        return prefix + UUID.randomUUID().toString().replace('-', '0');
}

rmarco · **User rating:** -

Support wrote:

Could you please provide an example code and a launch scenario for the case when when you manage to create two orders with the same label?
In a case you're only concerned about making your labels unique, you might consider the following method which ensures the label uniqueness between both of the strategies:

private String getLabel(String prefix){
        return prefix + UUID.randomUUID().toString().replace('-', '0');
}

For instance, the attached code. It works when runned twice through the jforex platform: One of the instances introduces the order, and the other throw the following exception:

Quote:

07:48:38 com.dukascopy.api.JFException: Label not unique(code 2). (Order already exists) [DLUSDJPY20110525_094830]:label=DLUSDJPY20110525_094830;getId()=null;groupId=null;openingOrderId=null;pendingOrderId=null;parentOrderId=null;tpOrderId=null;slOrderId=null;state=CREATED;instrument=USD/JPY;openPrice=82.151;requestedAmount=0.01;amount=0.01;lastServerRequest=SUBMIT;awaitingResubmit=false;localCreationTime=1306309718116;

But when I run the strategy two times at the same time through Java API, I got no exception, and two orders are introduced with same label. See the screenshot:

https://postimage.org/image/1n0uysfb8/

Labels DLEURUSD20110525_095850 and DLEURUSD20110525_095910 are duplicated. Label DLEURUSD20110525_095900 is not, because that time it worked fine: one of the instances detected the duplicated label and throw the exception.

Source code:

package jforex;

import java.text.SimpleDateFormat;

import com.dukascopy.api.*;

public class DuplicatedLabel implements IStrategy {
    private IEngine engine;
    private IConsole console;
    
    public void onStart(IContext context) throws JFException {
        this.engine = context.getEngine();
        this.console = context.getConsole();
    }

    public void onAccount(IAccount account) throws JFException {
    }

    public void onMessage(IMessage message) throws JFException {
    }

    public void onStop() throws JFException {
    }

    public void onTick(Instrument instrument, ITick tick) throws JFException {
    }
    
    public void onBar(Instrument instrument, Period period, IBar askBar, IBar bidBar) throws JFException {
        if (period!=Period.TEN_SECS) return;
        
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd_HHmmss");
        String label = "DL"+instrument.toString().replaceAll("/", "")+sdf.format(bidBar.getTime());
        console.getOut().println("Introducing order BUY "+instrument.toString()+" with label "+label);
        try {
            engine.submitOrder(label, instrument, IEngine.OrderCommand.BUY, 0.01);
        } catch (Exception e) {
            console.getErr().println(e.toString());
        }
    }
}

rmarco · **User rating:** -

I am not concerned about making my labels unique, but rather I do not want to duplicate orders if I launch more than one instance of my strategy in different computers (I may do that to ensure order execution if one of them is offline).

API Support

Current implementation doesn't check label uniqueness on server side, meaning that label uniqueness is ensured only within a process which runs the strategy.
You can ensure label uniqueness by putting as label's prefix the process name or pc name (in case if you never run your strategy in two different processes on the same pc). For example:

   String pcName = InetAddress.getLocalHost().getHostName();
   String processName = ManagementFactory.getRuntimeMXBean().getName();

Guest · **User rating:** -

Thank you for your answer, however my problem is exactly the opposite: I don't want to avoid duplicated label, but to avoid duplicated orders.

What I want to do is to have two servers running one strategy. So when I insert an order, I want just one order, not two of them with different labels. If labels were unique, it wouldn't be a problem: the fastest server inserts the order and the slower one gets an error.

Is there any way I could do this without forcing one server to wait some random time to ensure the other one is not running?

Thank you very much,

API Support

Guest wrote:

Is there any way I could do this without forcing one server to wait some random time to ensure the other one is not running?

No you can't.

Current JForex API implementation doesn't support communication between IClient or IStrategy instances that are located in separate processes. If you wish to check labels of orders from another process you might, for instance, consider using a web service. In this case before a submission of any order you would need to wait for the response from the service to arrive.