I am investigating the possibilities to use IPC between a Lazarus and a Delphi7 application running on Windows. I was discussing this on the Lazarus forum where I got a tip to use SimpleIPC, which apparently is delivered with the Fpc compiler itself.

The tip was given in this post:
https://forum.lazarus.freepascal.org/index.php/topic,62867.msg475663.html#msg475663

In that post is a link to a GitHub project which simplifies ipc usage by creating a dll packaging everything needed so that the dll could be used from other applications developed in other languages too. Sounds good to me. Here is the GitHub project url:
https://github.com/z505/SimpleIPC-lib

So I downloaded this and using Lazarus 2.2.4 and Fpc 3.2.2 on Windows 10 x64 I did this:
1) opened the dll project and compiled the dll itself.
2) Opened the demo-lazarus\ipcclient project and compiled it
3) Opened the demo-lazarus\ipcserver project and compiled it

So now I could start the ipcclient app and it shows its form with a button to send data to the server. When I used it there was an error message about "not finding the server". To be expected, since I had not started the server...

So I next tried to start the server app, but it immediately shows an error box with the text:
-------------------
Application error
The application was unable to start correctly (0xc000007b). Click OK to close the application.
[OK]
-------------------

I have tried various things like changing target for the dll and both applications to win32 (I have the cross for Win32 installed), but the exact same happens.

And I have no idea whatsoever on where to look for a reason for this to happen.

I have even put a breakpoint into the server code at the earliest point I could find and started it from Lazarus, but get the same error dialog and no breakpoint reached...

I tried reading https://wiki.freepascal.org/SimpleIPC but got no idea from that either...

What to do now?
I am not clever enough to figure out if there is some error in the GitHub project. Not used to windows I want to do is to create an ipc link to a Delphi7 server app from a Lazarus/fpc client app to use the D7 app to read a hardware device on command and send the data to the Lazarus app.
It is not possible to compile the D7 app on Lazarus because there is a device manufacturer's obj file involved and it is apparently of the wrong format for Lazarus/Fpc to use. It can be linked to in Delphi7 but not in Lazarus/Fpc.

Hence the D7<=ipc=>Lazarus IPC communication...

I really do hope this can be fixed so I can get the ipc comm line to the D7 interfacing app working!

Considering everything will run on Windows,? it could be easy to use COM / OLE Automation:

- making your delphi part as COM Server

- connecting as client in your Lazarus app, so you can call directly objects and functions defined in the Delphi app.

There is a bit of stuff to learn about COM to complete this but it's well documented and directly available on both sides, Delphi and Lazarus.

Among the internet examples of Delphi 7 you should find a small app named netchat, which provides a basic IPC. It?s quite simple and bullet-proof. I?ve converted to Lazarus on Linux, and used as a base for my needs of IPC. But converting on the same Windows environment should be very simple, just using the Lazarus facilities. You may test it just as it is, and then adapt it to your needs. Giuliano

Inviato da iPhone

Where are the "internet examples of Delphi 7" located? Inside the Delphi7 installation or where? I can't find any.

By the name you write it looks to me (without having found the example) that it is a *network* application using TCP/IP sockets or the like. I know this is a possibility but seems to be problematic since it implies that the communication is via the LAN. What about situations when there is no network connection?

The IPC as described seems to use internal messaging channels on the Windows computer it runs on and not the network...

So I pulled out my Delphi7 CD (actually mounted the ISO copy of the CD) and managed to find the demo you refer to.
It is as I suspected using the TCP/IP socket communications, but I guess this is the way I have to go.
I can probably set it to only operate on the localhost interface so there is no need to get packets out onto the LAN, which may or may not be available.

And I can use Indy10 sockets rather than the now since long deprecated TTcpClient and TTcpServer components.

I guess I will save myself a lot of time doing this...

Il 01/04/2023 09:37, Bo Berglund via lazarus ha scritto:

I have found it on the Kylix installation. But I did a quick search of Delphi NetChat and I found it immediately. It should be in the Demos folder. Demos->Internet->NetChat. You may also download it from Internet, where a Brazilian guy has made it available: http://simbolussi.ddns.com.br:8088/TESTE%20DELPHI%207/Delphi7/Delphi7/Demos/Internet/NetChat/

Yes it is a network app, but it can be used locally, just by connecting both sides via localhost (i.e. 127.0.0.1), the loopback interface, which can be used whenever you want to connect TCP/IP server-client on the same machine. It's fundamental to test network apps locally before deploying it.
Just search for "windows localhost", and you'll get the Microsoft documentation about it:
https://learn.microsoft.com/en-us/windows/iot-core/develop-your-app/loopback and other contributions which may be useful.

That way you'll be using tools which are widely used and tested, and not very special ones which may fail outside a particular environment.

Giuliano

Il 01/04/2023 10:53, Bo Berglund via lazarus ha scritto:

And I can use Indy10 sockets rather than the now since long deprecated TTcpClient and TTcpServer components. I guess I will save myself a lot of time doing this...

If I were you I'd take ten minutes to give it a try. Just compile, launch two instances, and type in one and see the message in the other. Then decide which way to go. AFAIK all the Internet servers and clients around the world are using tcp/ip and none of them Indi10.... If Windows wants to connect reliably to Internet must provide a good implementation of the tcp/ip protocol, which is just exploited by the TTcpClient and TTcpServer components.

Giuliano

You can uses pipes too, basically just two files no need of networking, one for reading (delphi to freepascal), one for writing(freepascal to delphi).

I made last year a small app to communicate with Audacity (https://www.audacityteam.org/) using a specific plugin (https://manual.audacityteam.org/man/scripting.html).

You can find there the unit/class which manages the communication: https://github.com/jsuzineau/pascal_o_r_mapping/blob/TjsDataContexte/tools/jsAudacity/uAudacity.pas

In my case I used pipes already created by Audacity. For your problem I think it would be more appropriate to use FpPipe (although I personnaly never used it):

https://www.freepascal.org/docs-html/rtl/baseunix/fppipe.html

I think you will find something similar on Delphi 7 side.

Il 01/04/2023 14:50, Jean SUZINEAU via lazarus ha scritto:

I'm afraid that Jean Suzineau is right, except for the reference to FpPipe which is Unix specific.

Named pipes (or FIFO's) may be the simplest solution, in place of a bloated Indi10, useful if you need something quite complex, such as a securized web server , or of the tcp/ip sockets of NetChat. Just a file you write on one side and read the on the other side. Two named pipes for bidirectional communication, if necessary.

You'll find a lot of examples just looking for Delphi pipes or Delphi named pipes on the web.
https://github.com/Poznamenany/Named_Pipes_in_Delphi is just one for Delphi side (but it's ok also for Lazarus).

You may find useful the discussion here, to avoid common pitfalls: https://forum.lazarus.freepascal.org/index.php?topic=44251.0

Giuliano

What I want to do is...use the D7 app to read a hardware device on command and send the data to the Lazarus app.

You probably don't need the extra complication of IPC, sockets, COM, or OLE automation. Instead of creating a D7 app, build a D7 DLL which exports the function(s) you need. Import the DLL function(s) to your Lazarus app and call them directly.

Wayne Sherman via lazarus schrieb am So.,
2. Apr. 2023, 02:45:

Since the Delphi code in question is 32-bit that will restrict the FPC code to i386-win32.

Regards,
Sven

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