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Sharing data between 2 Metatrader terminals

  • #1
  • First Post: Jul 3, 2011 5:51pm Jul 3, 2011 5:51pm
Well, I've been trying this for a little while now. I don't understand why it's not working. Both terminals (IBFX and Alpari) load just fine. The EA's load w/ no errors. The EA's compile w/ no errors. The DLL compiles just fine as well.

Any ideas anyone? I've included both EA's, the .cpp and .def files. If anyone has idea I'd greatly appreciate it.

The EA's have the same name, but one goes in IBFX and the other in Alpari's experts folder. It doesn't really matter which is which.

The EA doesn't do anything but put a vaule into the DLL for the other terminal to read and vice versa.

Note: The DLL was created and compiled in Visual Studio 2010.

Thank You in advance.
-Non.
Attached File(s)
File Type: zip EURUSD.zip   2 KB | 540 downloads
  • #2
  • Jul 3, 2011 11:05pm Jul 3, 2011 11:05pm
Try using debugview to printout the vars from the dll as they are being changed. That should tell you what is happening in the dll and give proof that the dll functions are actually being called. MT4 does not report errors on failed dll calls.

Debugview ref:
http://www.forexfactory.com/showthread.php?t=245303
  • #3
  • Edited Jul 4, 2011 12:38am Jul 3, 2011 11:07pm | Edited Jul 4, 2011 12:38am
Hi Non, haven't tried it, but possibly just a damn typo:

Inserted Code
 
#import "C:\4xArb\EURUSD.dll"
   double GetValueForAlpariromIBFX(double varPutValue);
#import

shouldn't it be GetValueForAlpariFromIBFX ?

Seems the dll expects the F to be there. The IBFX EA is ok. This typo in Alpari EA could be the reason; there's no chance to complete the exchange on either side since the Alpari EA does not send the value nor receives the value actually sent by IBFX EA because the 'transceiver' function isn't called on Alpari side.

just btw: this seems to be a nice tool for inter-MT4 data exchange (via registry):
http://fx1.net/wiki/pmwiki.php/PermVar/PermVar (free stuff)

edit: also take a look at this:
http://docs.mql4.com/runtime/imports
..maybe you should place the dll into experts\libraries folder, then don't use any path, just the filename (recommended in docs).. just rambling here but I don't suppose the dll doesn't load so don't care if it does..
MarginTrader All Time Return: na
  • #4
  • Jul 4, 2011 1:19am Jul 4, 2011 1:19am
Quoting Xaphod
Try using debugview to printout the vars from the dll as they are being changed. That should tell you what is happening in the dll and give proof that the dll functions are actually being called. MT4 does not report errors on failed dll calls.

Debugview ref:
http://www.forexfactory.com/showthread.php?t=245303
Thanks. Late at night now, but this is getting checked out and tried in the morning!
  • #5
  • Jul 4, 2011 1:19am Jul 4, 2011 1:19am
Quoting MaryJane
Hi Non, haven't tried it, but possibly just a damn typo:

Inserted Code
 
#import "C:4xArbEURUSD.dll"
   double GetValueForAlpariromIBFX(double varPutValue);
#import

shouldn't it be GetValueForAlpariFromIBFX ?

Seems the dll expects the F to be there. The IBFX EA is ok. This typo in Alpari EA could be the reason; there's no chance to complete the exchange on either side since the Alpari EA does not send the value nor receives the value actually sent by IBFX EA because the 'transceiver' function isn't...
DOH! Thanks. Good readers too!
  • #6
  • Jul 6, 2011 1:02am Jul 6, 2011 1:02am
fixed the spelling, tried what was in the links.

I haven't tried the registry exchange; as a former IS guy, I'm going to avoid that.

This should be able to be done via a DLL. I'm wondering why it can't.
  • #7
  • Jul 6, 2011 7:31am Jul 6, 2011 7:31am
Hey nondisclosure00,

I just want to point out that while what you did will work in this case, you have to be careful of race conditions. If 2 or more processes are directly writing to the same variable, the data could become corrupted.

In your current implementation this isn't a problem but in the future if you expand on this dll it might become a problem.

You might consider sangmane's named pipes implementation for safe interprocess communication if your needs get more complicated.

The post is here.
You are in a maze of twisty little passages, all alike.
  • #8
  • Jul 6, 2011 1:37pm Jul 6, 2011 1:37pm
Hey Steve,

Thanks for the reply. Pipes, to be honest, scare the hell out of me. My days as a hacker, I would LOVE to exploit this. One of the easyest things to do.

But Sangme came up w/ something far better. Check it out: http://www.forexfactory.com/showthread.php?p=4756260 . It's post #6.

What I have isn't working. I've been looking into mutex conditions to try to solve this issue. But I have no idea "how" to impliment this and I've been googling for days looking for an example in my case (shared memory for a dll).

All the DLL's I've written in the past have been single process usage only.

If you've got any ideas or sample code, I'd greatly appreciate it!

Quoting stevegee58
Hey nondisclosure00,

I just want to point out that while what you did will work in this case, you have to be careful of race conditions. If 2 or more processes are directly writing to the same variable, the data could become corrupted.

In your current implementation this isn't a problem but in the future if you expand on this dll it might become a problem.

You might consider sangmane's named pipes implementation for safe interprocess communication if your needs get more complicated.

The post is here....
  • #9
  • Jul 6, 2011 1:58pm Jul 6, 2011 1:58pm
For a c++ dll sharing a data segment is the simplest method:
http://msdn.microsoft.com/en-us/libr...=vs.80%29.aspx
Not sure it works in win7 though.

Next I'd suggest memory mapped files.
http://msdn.microsoft.com/en-us/library/ms810613.aspx

I think pipes use memory mapped files.
  • #10
  • Jul 6, 2011 2:51pm Jul 6, 2011 2:51pm
Pipes look like files in that you open them like a file and send and receive data through normal file IO calls.
You are in a maze of twisty little passages, all alike.
  • #11
  • Last Post: Jul 6, 2011 6:25pm Jul 6, 2011 6:25pm
Thanks. But it's still not working. I've been told I don't have a mutex sync or something like that.

My code matches what sniplet is in the link you have below:
.cpp
Inserted Code
[font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]
[size=2][font=Consolas][color=#0000ff]#define[/color][/font][/size][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2] WIN32_LEAN_AND_MEAN[/size][/font]
[/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]#define[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2] MT4_EXPFUNC [/size][/font][/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]_declspec[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2]([/size][/font][/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]dllexport[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2])[/size][/font]
[/size][/font][font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000][/color][/size][/font][/color][/size][/font][/color][/size][/font] 
[font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000]//Global variables w/ Global scope in DLL ONLY![/color][/size][/font]
[/color][/size][/font][/color][/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]#pragma[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]data_seg[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2] ([/size][/font][/size][/font][font=Consolas][size=2][color=#a31515][font=Consolas][size=2][color=#a31515][font=Consolas][size=2][color=#a31515]".MYSEG"[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2])[/size][/font]
[/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]double[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2] varIBFX=0.0;[/size][/font]
[/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]double[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2] varAlpari=0.0;[/size][/font]
[/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]#pragma[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]data_seg[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2]()[/size][/font]
[/size][/font][font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000][/color][/size][/font][/color][/size][/font][/color][/size][/font] 
[font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000]//For IBFX to put data and get back from Alpari[/color][/size][/font]
[/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2]MT4_EXPFUNC [/size][/font][/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]double [/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]_stdcall[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2] GetValueForIBFXFromAlpari([/size][/font][/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]double[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2] varPutValue)[/size][/font]
[size=2][font=Consolas]{[/font][/size]
[size=2][font=Consolas]varIBFX=varPutValue;[/font][/size]
[/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]return[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2](varAlpari);[/size][/font]
[size=2][font=Consolas]}[/font][/size]
[/size][/font][font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000][/color][/size][/font][/color][/size][/font][/color][/size][/font] 
[font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000][font=Consolas][size=2][color=#008000]//For IBFX to put data and get back from Alpari[/color][/size][/font]
[/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2]MT4_EXPFUNC [/size][/font][/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]double [/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]_stdcall[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2] GetValueForAlapriFromIBFX([/size][/font][/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]double[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2] varPutValue)[/size][/font]
[size=2][font=Consolas]{[/font][/size]
[size=2][font=Consolas]varAlpari=varPutValue;[/font][/size]
[/size][/font][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff][font=Consolas][size=2][color=#0000ff]return[/color][/size][/font][/color][/size][/font][/color][/size][/font][font=Consolas][size=2][font=Consolas][size=2](varIBFX);[/size][/font]
[size=2][font=Consolas]}[/font][/size]
[/size][/font]

.def
Inserted Code
[font=Consolas][size=2]
[size=2][font=Consolas]LIBRARY "EURUSD"[/font][/size]
[size=2][font=Consolas][/font][/size] 
[size=2][font=Consolas]EXPORTS[/font][/size]
[size=2][font=Consolas]GetValueForIBFXFromAlpari[/font][/size]
[size=2][font=Consolas]GetValueForAlapriFromIBFX[/font][/size]
[size=2][font=Consolas][/font][/size] 
[size=2][font=Consolas]SECTIONS[/font][/size]
[size=2][font=Consolas].MYSEG READ WRITE SHARED[/font][/size]
[/size][/font]

I am completely lost on this.

Quoting Xaphod
For a c++ dll sharing a data segment is the simplest method:
http://msdn.microsoft.com/en-us/libr...=vs.80%29.aspx
Not sure it works in win7 though.

Next I'd suggest memory mapped files.
http://msdn.microsoft.com/en-us/library/ms810613.aspx

I think pipes use memory mapped files.
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