Mission Critical: Broker feed drops during EA trading

For those of us that rely on EAs for trading (note that I said "rely" and not "use") I have noticed a potential devastating problem.

Assuming your EA uses any technical analysis indicators, a dropped data feed will probably alter the TA values (RSI, MA, etc...) This can lead to false signals....

How do you deal with that?

to me happin all time.
EA bad triggir ok ... so waht? just cost of doing buziniss.
plenti mor pip later.
ok, thank you.

Anyone have a better answer than this one? Tesla, Mikhail, Skyline.....

When you lose connection and then reconnect, your pricing tends to "stutter" in. What I mean by that is you'll see blocks of pricing data come in, starting with the oldest missing data.

The good news is that this means your indicators will update and will be accurate, provided they were built correctly.

The bad news is that, if this update data can trigger the start() function of your EA, you can get an entry or exit triggered off of old data. I haven't confirmed if the start function is indeed triggered when update pricing is received, but this should be trivial to test.


Since an EA only processes when the start() function is called, and the start() function is only called when a tick is received, it's not possible for an EA to check to monitor if you're disconnected with the IsConnected function (at least without seriously munging the workings of the EA). You could probably use a script to monitor connection state and trip a global variable when disconnects occur, but that seems like a rather inelegant solution.

I'll sleep on this one and see if I can't come up with a decent answer. I'm interested in reading what others have to say on this as well.

An EA doesn't trigger while disconnected and it doesn't trigger on updating history data. It will trigger on the next tick, after the gap has been filled. At that moment indicators should have the correct current values. The only situation I could imagine is an MTF indicator that uses bars from other timeframes, which have not yet updated fully – and the indicator thinks the last available bar is the current bar.

Missed entries and exits, obviously. But I don't see how false signals would be generated. Could somebody give an example, if I'm missing something?

After a bit of thought, I'm of the opinion that there's not much you can do about server disconnects. About all you can do is insure you have a "safety" stoploss on all positions to limit risk when your EA can't manage trades.

You can mitigate disconnect risk on your side by insuring that your internet connection is solid and redundant.

Iya put together a script to monitor connection state, I haven't looked at it but perhaps that's something you could make use of.

Is this speculation, or do you know it from experience? Thank you.

There will also be times when bars are missing due to the server being down. This can result in inaccurate indicator/EA calculations. If you go to the history tab, you are able to fill in the missing bars with data from another provider.

The more time I spend at this game, the more I plan to have accounts at multiple brokers, for when the inevitable happens. At least, have a demo from another broker up at all times, because you can still monitor the trade, and if it goes against, call the dealing desk and have them close it out for you.

Good luck.

Like Tesla suggested, I've tested it with a simple EA:
Start it on an old chart and monitor the output, while the history is updating. The output will look like this:

Hi
this is from MT4 help, i think it help
consider to use RefreshRates()


bool RefreshRates()
Refreshing of data in pre-defined variables and series arrays. This function is used when expert advisor has been calculating for a long time and needs data refreshing. Returns TRUE if data are refreshed, otherwise returns FALSE. The only reason for data cannot be refreshed is that they are the current data of the client terminal. If the data have been updated, the last quote incoming time will be updated, too. This time is returned by the TimeCurrent() function.

Experts and scripts operate with their own copy of history data. Data of the current symbol are copied at the first launch of the expert or script. At each subsequent launch of the expert (remember that script is executed only once and does not depend on incoming ticks), the initial copy will be updated. One or more new ticks can income while the expert or script is operating, and data can become out of date.
Sample:
int ticket;
while(true) { ticket=OrderSend(Symbol(),OP_BUY,1.0,Ask,3,0,0,"expert comment",255,0,CLR_NONE);
if(ticket<=0) { int error=GetLastError(); //---- not enough money if(error==134) break; //---- 10 seconds wait Sleep(10000); //---- refresh price data RefreshRates();
break;
} else
{ OrderSelect(ticket,SELECT_BY_TICKET);
OrderPrint();
break; } }

Nope. RefreshRates() doesn't work like that. If you have an EA that loops internally, or is busy when it's supposed to be dormant listening for ticks to fire the start() function, RefreshRates() lets you pull fresh quote data provided it's already been received by the client.

Since we're talking about quote server disconnects, the function will do you no good.