Named Pipe communication between two terminals

[user_123]

Dear Community,

I try using the Named Pipes to exchange data between two terminals. Unfortunately, I can not get it to work.. I've already read most of the entries in this forum regarding Named Pipes but found nothing suitable.

I can not find the error or problem in my code. I use the script "MyPipeWriter" in first terminal  and the script "MyPipeReader" in the second terminal.

The function:

ExtPipe.Open("\\\\.\\pipe\\MQL4.Pipe.MyPipeServer",FILE_READ|FILE_WRITE|FILE_BIN)

delivers all the time an invalid handle.

I would be very grateful if someone could give me a advice what I'm doing wrong. I try this in the MT4.

Thank you for your help!

//+------------------------------------------------------------------+
//|                                                 MyPipeWriter.mq4 |
//|                   Copyright 2012-2014, MetaQuotes Software Corp. |
//|                                              http://www.mql4.com |
//+------------------------------------------------------------------+
#property copyright   "Copyright 2012-2014, MetaQuotes Software Corp."
#property link        "http://www.mql4.com"
#property version     "1.00"
#property description "Pipe client sample using CFilePipe standard class"
#property strict

#include <Files\FilePipe.mqh>

CFilePipe ExtPipe;
//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart(){
//--- wait for pipe server
   bool bfirst=true;
   while(!IsStopped()){

      if(ExtPipe.Open("\\\\.\\pipe\\MQL4.Pipe.MyPipeServer",FILE_READ|FILE_WRITE|FILE_BIN)!=INVALID_HANDLE){
         Print("Test1");
         break;
      }
      
      if(bfirst){
         bfirst=false;
         Print("Client: waiting for pipe server");
      }
      
      Sleep(250);
   }
   
   if(IsStopped())
      return;
   
   Print("Client: pipe opened");
//--- send welcome message
   
   if(!ExtPipe.WriteString(__FILE__+" on MQL4 build "+IntegerToString(__MQL4BUILD__))){
      Print("Client: sending welcome message failed");
      return;
   }

   ExtPipe.Close();
}

//+------------------------------------------------------------------+
//|                                                 MyPipeReader.mq4 |
//|                   Copyright 2012-2014, MetaQuotes Software Corp. |
//|                                              http://www.mql4.com |
//+------------------------------------------------------------------+
#property copyright   "Copyright 2012-2014, MetaQuotes Software Corp."
#property link        "http://www.mql4.com"
#property version     "1.00"
#property description "Pipe client sample using CFilePipe standard class"
#property strict

#include <Files\FilePipe.mqh>

CFilePipe ExtPipe;
//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart(){
//--- wait for pipe server
   bool bfirst=true;
   while(!IsStopped()){
      if(ExtPipe.Open("\\\\.\\pipe\\MQL4.Pipe.MyPipeServer",FILE_READ|FILE_WRITE|FILE_BIN)==INVALID_HANDLE)
         break;
      
      if(bfirst){
         bfirst=false;
         Print("Client: waiting for pipe server");
      }
      Print("Test2");
      Sleep(250);
   }
   
   if(IsStopped())
      return;
   
   Print("Client: pipe opened");

//--- read data from server
   string str;
   int    value=0;

   if(!ExtPipe.ReadString(str))
     {
      Print("Client: reading string failed");
      return;
     }
   Print("Server: \"",str,"\" received");

   if(!ExtPipe.ReadInteger(value))
     {
      Print("Client: reading integer failed");
      return;
     }
   Print("Server: ",value," received");
//---
   ExtPipe.Close();
}

[Philippe Pauleau]

user_123 is right,  using recent MT4 builds, ExtPipe.Open function ( <Files\FilePipe.mqh> provided and included in MT4 ) always return INVALID_HANDLE

Why leaving  <Files\FilePipe.mqh> included file if they are not working anymore with latest build ?

[Alain Verleyen]

kariboo92:

user_123 is right,  using recent MT4 builds, ExtPipe.Open function ( <Files\FilePipe.mqh> provided and included in MT4 ) always return INVALID_HANDLE

Why leaving  <Files\FilePipe.mqh> included file if they are not working anymore with latest build ?

You can't use MT4/MT5 as a server, only as a client.