• Use commerce/place monitoring. It is easy, dependable and requires no cooperation from the opposite EA.

• If you happen to can not distinguish which EA positioned a commerce, let the person choose a commerce from historical past to “observe”, or auto-detect the primary commerce after attaching your EA and retailer its magic/remark to observe subsequent trades.

Instance MQL5 EA — listens for different EAs’ commerce exercise and reacts

This EA:

• builds a set of at present recognized place tickets on init,

• makes use of OnTradeTransaction() to detect commerce modifications,

• when it sees a new place open or place closed, it calls OnExternalSignalDetected(…) the place you place your customized motion (open hedge, notify, and many others.),

• reveals easy methods to auto-detect the opposite EA’s magic/remark or let person specify it.

Paste the code into MetaEditor as a brand new EA and compile.

#property copyright "Instance"
#property model   "1.00"
#property strict

enter lengthy   FollowMagic = -1;    
enter string FollowComment = "";  
enter bool   AutoDetect = true;   


ulong knownTickets[];




void AddKnownTicket(ulong ticket)
{
   for(int i=0;i<ArraySize(knownTickets);i++)
      if(knownTickets[i]==ticket) return;
   ArrayResize(knownTickets, ArraySize(knownTickets)+1);
   knownTickets[ArraySize(knownTickets)-1] = ticket;
}




void RemoveKnownTicket(ulong ticket)
{
   int idx=-1;
   for(int i=0;i<ArraySize(knownTickets);i++)
      if(knownTickets[i]==ticket) { idx=i; break; }
   if(idx==-1) return;
   for(int j=idx;j<ArraySize(knownTickets)-1;j++) knownTickets[j]=knownTickets[j+1];
   ArrayResize(knownTickets, ArraySize(knownTickets)-1);
}




bool IsKnownTicket(ulong ticket)
{
   for(int i=0;i<ArraySize(knownTickets);i++)
      if(knownTickets[i]==ticket) return true;
   return false;
}




int OnInit()
{
   ArrayResize(knownTickets,0);
   
   int whole = PositionsTotal();
   for(int i=0;iif(PositionSelectByIndex(i))
      {
         ulong ticket = (ulong)PositionGetInteger(POSITION_TICKET);
         AddKnownTicket(ticket);
      }
   }
   Print("FollowExternalTrades initialized. Recognized positions: ", ArraySize(knownTickets));
   return(INIT_SUCCEEDED);
}




void OnDeinit(const int cause)
{
   
}




void OnTradeTransaction(const MqlTradeTransaction &trans,
                        const MqlTradeRequest &request,
                        const MqlTradeResult &outcome)
{
   
   
   DetectPositionChanges();
}




void DetectPositionChanges()
{
   
   ulong currentTickets[];
   ArrayResize(currentTickets, 0);
   int whole = PositionsTotal();
   for(int i=0;iif(PositionSelectByIndex(i))
      {
         ulong ticket = (ulong)PositionGetInteger(POSITION_TICKET);
         ArrayResize(currentTickets, ArraySize(currentTickets)+1);
         currentTickets[ArraySize(currentTickets)-1] = ticket;
      }
   }

   
   for(int i=0;i<ArraySize(currentTickets);i++)
   {
      ulong t = currentTickets[i];
      if(!IsKnownTicket(t))
      {
         
         if(PositionSelectByTicket(t))
         {
            lengthy magic = (lengthy)PositionGetInteger(POSITION_MAGIC);
            string remark = PositionGetString(POSITION_COMMENT);
            string sym = PositionGetString(POSITION_SYMBOL);
            double vol = PositionGetDouble(POSITION_VOLUME);
            int ptype = (int)PositionGetInteger(POSITION_TYPE); 
            datetime time = (datetime)PositionGetInteger(POSITION_TIME);

            
            bool match = true;
            if(FollowMagic>=0 && magic!=FollowMagic) match = false;
            if(StringLen(FollowComment)>0 && remark!=FollowComment) match = false;

            
            if(AutoDetect && FollowMagic==-1 && match)
            {
               FollowMagic = magic;
               PrintFormat("Auto-detected FollowMagic = %d (remark="%s")", FollowMagic, remark);
            }

            
            if((FollowMagic==-1 || magic==FollowMagic) && (StringLen(FollowComment)==0 || remark==FollowComment))
            TIME_SECONDS));
               OnExternalSignalDetected(true, t, sym, ptype, vol, magic, remark, time);
            

            
            AddKnownTicket(t);
         }
      }
   }

   
   
   int knownCount = ArraySize(knownTickets);
   for(int i=knownCount-1;i>=0;i--)
   {
      ulong t = knownTickets[i];
      bool stillExists = false;
      for(int j=0;j<ArraySize(currentTickets);j++) if(currentTickets[j]==t) { stillExists=true; break; }
      if(!stillExists)
      {
         
         PrintFormat("Detected CLOSED place ticket=%I64u", t);
         OnExternalSignalDetected(false, t, "", -1, 0.0, 0, "", 0);
         RemoveKnownTicket(t);
      }
   }
}





void OnExternalSignalDetected(bool is_open, ulong ticket, string image, int pos_type, double quantity, lengthy magic, string remark, datetime open_time)
{
   
   
   
   
   
   

   if(is_open)
   {
      
      PrintFormat("*** ACTION: exterior OPEN detected. Ticket=%I64u image=%s sort=%d vol=%.2f magic=%d remark=%s",
                  ticket, image, pos_type, quantity, magic, remark);

      
      
      
      

   }
   else
   {
      PrintFormat("*** ACTION: exterior CLOSE detected. Ticket=%I64u", ticket);
      
   }
}




bool PositionSelectByTicket(ulong ticket)
{
   
   for(int i=0;i<PositionsTotal();i++)
   {
      if(PositionSelectByIndex(i))
      {
         if((ulong)PositionGetInteger(POSITION_TICKET) == ticket) return true;
      }
   }
   return false;
}




void OnTick()
{
   
}