Passing data from one MT4 client to another

my goal is to transfer data from one terminal.exe process to another one....

i do not want to use text files because of the collisions that can occur....

my first thought was to create a DLL with shared memory space, and import it into each MT4 terminal.... then read from one EX4 and write with the other one...


for anyone that has used Terranin's MT4 copier, he has found a solution to the problem.... but his response via PM was too complex for me.

help

You wont be able to create a shared memory space directly within DLLs.

There are several ways of getting DLLs to talk to each other. It depends really if you want two way coms or not, and how frequently they need to converse. The easiest methods include :

1) Open sockets within the DLLs to talk via TCP or other protocol. (probably easiest and works if MT4 apps are on different machines on LAN or over inet)

2) Have one MT4 use a DLL that creates a 'helper' window (visible or invisible) and then implement WM_COPYDATA messages using SendMessage either directly from MT4 or from another DLL.

If this is beyond you then you could use disk files to pass the data if youre not transfering too frequently, you'll just have to use ancillary files as a semaphore mechanism. Again it really depends on how youre trying to communicate but this should work inside an EA (not an indicator).
(However you'll have to use windows API file functions because as far as I know MT4 wont write or read outside of its own directory structure)

'Datafile.txt' contains your data
'app1lock.txt' ... dummy lock file
'app2lock.txt' ... dummy lock file

before startup of either MT4 app ensure no files exist


App1 ...

if app2lock.txt does not exist
{

create file app1lock.txt

/// its possible at this point that both apps locked almost simultaneously so wait and check again

sleep(1000); // wait a second

if app2lock.txt does not exist
{
create / modify / read 'datafile.txt'
} else flag that we need to redo nexttime through

delete file 'app1lock.txt'
}

App2 ...

if app1lock.txt does not exist
{
create file app2lock.txt

Sleep(1500)

if app1lock.txt does not exist
{
create / modify / read 'datafile.txt'
} else flag for next run through

delete file 'app2lock.txt'
}

thanks. i will look at what you've done.

i found this on my own:
http://forums.devx.com/showthread.php?t=157293

unfortunately C++ isn't my strong suite.

Creating a shared resource as per that thread will only work within the frame work of the same instance of a process/application

So for example if you had an indicator (that uses a DLL) and attached to several charts in the same MT4 app then they would all open an instance of the DLL using the Hinstance handle of the MT4 App. They would be able to share the memory, because each instance of the DLL was opened with the same Hinstance handle of the same MT4 application.

You want to talk between two MT4 Apps. Each MT4 App has its own Hinstance handle so therefore if you opened the same DLL on two different Mt4 Apps then each would have its own separate chunk of shared memory, and therefore wouldnt be able to communicate.

thanks for the replies.

i need to create an application similar to what terranin has accomplished here:

http://www.forexfactory.com/showthread.php?t=42357

I have not yet done this, but think it will work: import user32 - see example on www.metatrader.info/node/160 and use the dde functions (sorry I can not find an example of this) or the send_message functions. (This is asuming both MTs are on the same computer).
Here's some thoughts on dde:
http://www.answers.com/topic/dde-con...cat=technology
DDE send is already built in, just need to do the receive on the 2nd instance. I will see what else I can find.

I threw this together between trades so its not the most amazing piece of code but it works

What can I say ... I was bored and feeling generous at the same time !!!

What is it :

A DLL and example EA (with source) to allow cross talk between two MT4 Apps on the same machine, using a FIFO text string message queue.

Only run one copy of the EA on a single MT4 APP and apply it to no more than 2 separate MT4 Apps on the same machine.

I wouldnt advise trying to use it in strategy tester but it may work in visual mode.

Usage
copy EX4 & MQ4 to the experts folder of 2 MT4 Apps
copy basicmsgdll.dll to the experts\libraries folder of 2 MT4 Apps


The EA has 1 external parameter 'runasserver' default = true

Drop the EA onto a chart in APP 1 and set runasserver =True
Drop the EA onto a chart in APP 2 and set runasserver = False

Enjoy!

Gratuitous thanks required!!

Post payments to the charity of your choice.

BTW. You wont know you have a new message until the next tick arrives, and forces the EA to run again. (I.E. The EA wont wake up when you send it a message) I Dont know what Hack Terranin is using to force an EA to run. If you post his EA then I can have a look but I doubt its in the EA code somehow.

Quote

Disliked

TimeDelaySec - defines time delay between checking for changes in orders (in seconds). If this parameter = 0 (default) then software works as usual and checks for changes on every tick (price change in terminal). This can cause big delays if price changes rarely, but this is how experts should work in MetaTrader. In opposite if you set this parameter to 1 or more seconds - you will get really fast copying of orders even if price did not change during this time. But this in not documented feature in MetaTrader and this causes situation when you can not open expert properties dialog after some time. Though you can fix this problem by changing timeframe on that windows where expert works.

Say RB: Many thanks for that contribution!
Can you do that in C#?
OR, where can I get the includes for delphi?
And - is there a free delphi compiler somewhere?
Thanks, Ken

Thank you for your effort, rangebound.

There is no hack to forcing an EA to run periodically. You just don't return from the start() call on the first tick. (You do have to wait for that first tick).

The trick is that you need to check the IsStopped() flag at least every 2.5s. If the user asks MT4 to stop/unload the EA, MT4 will make IsStopped() begin returning true and wait for upto 2.5s for the EA to return from that original start call. If you don't do it, MT4 will simply interrupt you code in an undignified manner.

A related trick is that you don't want to have a 'wild' loop that polls something over and over and over just as fast as the code can execute. You will consume all of the CPU time and make everything seem sluggish. If nothing else, just call Sleep somewhere in your main loop.

Most of the windows blocking functions will have a time out parameter (for ex. WaitForSingleObject (to wait for something like an external process to quit)) The return value will typically allow you to distinguish between a return due to the desired event occurring and a timeout occurring. If you were waiting on some long-run process you could have a loop that waits for the process for upto 500ms with WaitForSingleObject, checks the return value to see if WaitForSingleObject merely timed-out. If it did timeout, you could check IsStopped() to see if you should quit the EA and if it is still false continue to loop.

//untested and incomplete code meant only to give the gist of the concept
while(1)
{
ret = WaitForSingleObject(someProcessHandle, 500);
if (ret == WAIT_OBJECT_0 || IsStopped()) break;
}

Thanks for the post Royce .. It did cross my mind over the w/e that you could just hold the loop forever and sleep it, in any number of ways.

Kenz

Sure you can do it in C#, however Im not sure why you'd want to, unless you want to modify / augment it, and If you want to do that then it would be obvious to you whats needed.

I havent coded in C for a number of years and for several reasons mostly because you can do anything in delphi that can be done in C (all bar virtual device drivers) Delphi provides a much richer component / object set. Is much less prone to bugs since its far more readable, and the compiler allows you to write inline assembly code if you need to get the most speed out of a routine.

If your hell bent on converting it then :
All the windows functions are from user32.dll
You'll have to build your own TStringList class which is just a linked list object that stores strings (as far as Im aware C still doesnt supply such basic but highly useful classes as standard)
or you could just implement your own string handling with a dynamic array.

Do you know if with the newer versions of MT4, can they now read/write TXT files outside their own directory?
I would like to do something like what your talking about.

Thank you

EDIT: I created a little looping DOS batch file that will copy a file from one directory to another but what is the correct mq4 code I need to create the file and read the file when certain conditions are met?
Thanks
Here is the batch file if interested;
:loop
xcopy c:\temp\test.csv c:\temp2
del c:\temp\test.csv
goto:loop

I know I said I would not post anymore, but I am in an absolute bind. I have wasted almost 20 hours this weekend researching this problem, and am starting to feel helpless.

My problems are

1. I don't have visual c++ or VB
2. I have Dev C++, but do not know how to use MingW to create a DLL

I am attaching my attempt at a DLL for communicating between MT4 terminals. The idea is to use Win32 environment variables a semaphore and argument passers. The COMMAND_SENT variable is a semaphore, and OPERATION is used to exchange info.

Please.... I just can't go on wasting all these hours with DLLs....

// copy.cpp
#include <windows.h>
#include <string>
#include <cstdlib>
extern "C" {
//////////////////////////////////////////////////////
// broker A calls this to signal a new task (after it find it false w/ checkCommand().... hence, the semaphore.)
void WINAPI CommandSent(void) {
int success = 0;
while(!success)
success = putenv("COMMAND_SENT=1");
}
//////////////////////////////////////////////////////
// broker B calls this after it completes it's activity (sets it to false, letting broker A know that the previous activity is done)
void WINAPI CommandExecuted(void) {
int success = 0;
while(!success)
success = putenv("COMMAND_SENT=0");
}
//////////////////////////////////////////////////////
// broker A calls this to check for new tasks
// broker B calls this to check for completion of the previous activity
string WINAPI CheckCommand(void) {
return getenv("COMMAND_SENT");
}
//////////////////////////////////////////////////////
// open order format: B_001_45_115
// close order format: C_001_______
void WINAPI SetOperation(string op, string ticket, string stop, string tp) {
int success = 0;
string s = "OPERATION=" + op + "_" + ticket + "_" + stop + "_" + tp;
char *x = new char[21];
strcpy(x, s.c_str());
while(!success)
putenv(x);
delete []x;
}
//////////////////////////////////////////////////////
string WINAPI CheckOperation(void) {
return getenv("OPERATION");
}
//////////////////////////////////////////////////////
}


Please post suggestions or PM me if you can help! Thanks!

Tonight I discovered that kernal32.dll has some environment variable getter and setters built into it.

So (in theory) I can import kernal32.dll into my MQ4 code, and then call those functions. I am worried about it returning a pointer to an array of characters instead of the standard "string" datatype of MQ4.

Here is a link I was reading:
http://babek.info/libertybasicfiles/.../nl126/api.htm


What do you guys think? Does anyone have experience with this?

Tdion: I'm curious as to why you don't use the chat supplied by rangebound in post #7...??? Thanks, Ken
(ps: RB: I wanted this in C# because I'm working in NinjaTrader).

Tdion :

As Kenz suggests why not use the DLL supplied? I supplied the source and compiled DLL as freeware .... you may use it for any purpose even if it ends up in a saleable system ... Im not about to sue your ass! or claim property rights.
As for your DLL code Im not sure what your exact problem is?

Can you compile to a Callable DLL?
Is the code/logic not performing as desire?

At first glance I can see a flaw in your strategy. I doubt the windows functions to get and set environ vars are reentrant (very few Winapi functions are) this raises the same problem as seen in the text file example - namely - since you have two independent processes checking and modifying the same location it is entirely possible that one process may be partway through checking / setting the var when the other app checks / sets it. Without using established multitasking OS semaphore mechanisms this is likely to occur.

KENZ :

OK. I've not used Ninja trader though it has been on my todo list. (Its a bolt on to Futures betting who Im looking to open an acount with)

The only info I know about NT is that it uses C syntax in it language. I guess there'll be some syntax differences to bonafide C somewhere along the line though.

You should be able to port the delphi code, if DLL calling isnt a problem.
You should get by with one of the following includes :
(although you may need to use sendmessageA rather then sendmessage etc.)

winuser.h
windows.h


you'll still have to 'reinvent' the Tstringlist class but the same could be achieved using a staticly sized (large enough) array of strings and then just shuffle the strings up the array within the getmsg function.

As long as DLL imports/calls are available in NT you could still use the Delphi DLL supplied. I guess your biggest (possible) problem is getting the handle of a window within NinjaT ?

If this is your only problem then you can check / try out the Delphi DLL if you have C# or visual studio then you can get the handle of any window within NinjaT by using Spy++ or its 'studio .net' equivilent. Once you have a handle you can hard code the call to inititalise the message dll just to see if it will work as required. If it works OK then you can use a few Winapi calls to automate getting the handle of a Ninja window.

Can you post some chunks of Ninja code, preferably some that include DLL imports & calls

RB: sample C# sharp code for NT
most of that nasty looking code at the bottom is generated by NT, but you can see it's quite a bit different from C++
I don't have an indicator that calls a dll, but I think something like this is needed:
[DllImport("user32.dll", EntryPoint="GetDesktopWindow")]
public static extern IntPtr GetDesktopWindow();
I have not had time to test this out - I want a call to a dll that will do SendKeys. Also maybe later on have one that will do DDE both ways. Just need time to test. If you plan on learning this there is much info on microsoft msdn site. Ken.

OK. Had a quick look at some of the Ninja forums etc. It seems they've implemented .NET framework in the latet version so you should be OK with DLLs however their support team will not give out examples of DLL calls (Odd!)

Anyway.

Can you clarify what you want to do exactly

1) Call a 'Sendkeys' DLL from which App? - to press keys in which App?

2) you want to DDE between which two APPs?

RB: Thanks for looking at that. NT is on .NET ver 2. I have code in VB to do the different things I want, but C# is a new beast to me - I can not get the syntax right for the dll call - at compile time it tells me invalid format on the user32 call. This is somewhat low priority as I have other projects going on. NT support is not all that great with things like this - their standard answer is "not supported". The first thing I would like to do is just get a simple call to do PlaySound. That will give me the syntax and a place to start. After that I can do the code. Ken.

I got a simple MsgBox to display a popup message. Any thing more complicated gives me an error "Trying to read/update protected memory." Enough for now, this takes too much time.