A simple fast IPC based on Windows Messaging

[Nine 632]

After seeing a number of threads talking about how to exchange efficiently messages between processes (Inter Process Communication), I decided to create a framework using Windows Messages WM_COPYDATA.  What is new with this UDF you ask ?  Well it will depends how familiar you are with IPC.  One thing is sure, the simplicity of use and the fabulous speed are amazing.

This is based on a Clients-Server approach.  You can have an unlimited number of clients talking with a single server.  You will have to define the protocol of communication between them, but the code you have to create is incredibly low. The UDF proposes 2 simple message properties of communication.  The first (called data) is based on a number.  You can decide what value 1,2,3, etc. means between your client and server.  Server will react upon the value of the data field.  Second, there is a string field where you can inscribe additional information on request, and where the server will respond to client request (if necessary).

Here are the functions that I have wrapped around this :

Func _WCD_CreateServer 
Func _WCD_CreateClient 
Func _WCD_GetServerHandle 
Func _WCD_IsServerAvailable 
Func _WCD_Send
Func _WCD_WM_COPYDATA_CLIENT_HANDLER
Func _WCD_Client_GetResponse 
Func _WCD_WM_COPYDATA_SERVER_HANDLER
Func _WCD_Server_PeekRequest 
Func _WCD_Server_GetRequest 
Func _WCD_Server_IsRequestAvail 
 

Here an example of the server :

#include <Constants.au3>
#include <GUIConstants.au3>
#include "WCD_IPC.au3"

Opt ("MustDeclareVars", 1)

$_WCD_Verbose = False ; make it True if you want to follow the convos.  False is by default.

Local $hServer = _WCD_CreateServer ()
Local $aReq, $iData

While True
  If _WCD_Server_IsRequestAvail () Then
    $aReq = _WCD_Server_GetRequest ()
    $iData = @extended
    Switch $iData
      Case 1  ; who are you
        _WCD_Send($hServer, $aReq[0], $iData, @ComputerName)
      Case 2
        Switch Number($aReq[1])
          Case 1
            _WCD_Send($hServer, $aReq[0], $iData, @IPAddress1)
          Case 2
            _WCD_Send($hServer, $aReq[0], $iData, @IPAddress2)
          Case 3
            _WCD_Send($hServer, $aReq[0], $iData, @IPAddress3)
          Case 4
            _WCD_Send($hServer, $aReq[0], $iData, @IPAddress4)
          Case Else
            _WCD_Send($hServer, $aReq[0], $iData, "Invalid parameter")
        EndSwitch
    EndSwitch
  EndIf
  Sleep (100)
WEnd

And the client :

#include <Constants.au3>
#include <GUIConstants.au3>
#include "WCD_IPC.au3"

Opt ("MustDeclareVars", 1)

$_WCD_Verbose = True ; as for the server, you can decide to make client verbose or not
Global $hWnd = _WCD_CreateClient ("Test WCD Client")
Global $hWndServer = _WCD_GetServerHandle ()

_WCD_Send($hWnd, $hWndServer, 1) ; simple request - who are you ?
Local $sString = WaitForResponse ()
ConsoleWrite ($sString & @CRLF)
_WCD_Send($hWnd, $hWndServer, 2, "5") ; adding text to a more complex request
$sString = WaitForResponse ()
ConsoleWrite ($sString & @CRLF)

Func WaitForResponse ()
  Local $sResp
  While _WCD_IsServerAvailable ()
    $sResp = _WCD_Client_GetResponse ()
    If $sResp <> "" Then Return $sResp
    Sleep (100)
  WEnd
EndFunc

As always, let me know if you got issues, comments, suggestions.  I will be glad to answer.

Version 2020-06-27

* Allows processes with different levels of privilege to communicate with each other

 

 

WCD_IPC.au3

Edited June 27 by Nine

[argumentum 484]

..at a same level of execution ( user - user, admin - admin ), this approach is good but otherwise ( user - admin ), it won't communicate as is. Tested just now.

[Nine 632]

@argumentum Out of curiosity, just how exactly did you do your test between user-admin ?

[Chimp 647]

... I suppose by placing a #RequireAdmin on one of the scripts (?)

Edited May 1 by Chimp

[argumentum 484]

8 hours ago, Nine said:

Out of curiosity, just how exactly did you do your test between user-admin ?

to quote @Chimp, "by placing a #RequireAdmin on one of the scripts"  

[Nine 632]

I see.  Oh well, que sera sera.  Anyway, it was not intended for a mix of credentials.

[Bilgus 147]

but I can be with a bit moar work..

[water 2,280]

Added to the wiki

[Nine 632]

New version available :

As per @argumentum suggestion, I added IPC between different levels of execution