SimpleIPC - should it work ?
lazarus / 32-Linux

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dbannon · 2019-12-07 01:55

Hi Folks, I have been playing with the two SimpleIPC components on the
Lazarus System Tab without any success. In its simplest form, here is
what I am doing -
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.FormShow(Sender: TObject);begin   
SimpleIPCClient1.ServerID:='tomboy-ng';   
SimpleIPCServer1.ServerID:='tomboy-ng';    if
SimpleIPCClient1.ServerRunning then begin        Label1.Caption := 'I
am a client';        SimpleIPCClient1.Active := true;       
SimpleIPCClient1.SendStringMessage('SHOWSEARCH');    end else begin  
    Label1.Caption := 'I am a server';       
SimpleIPCServer1.Global:=True;                  // anyone can connect 
      SimpleIPCServer1.Active := true;                // start
listening    end;end;                   procedure
TForm1.SimpleIPCServer1Message(Sender: TObject);begin   
SimpleIPCServer1.ReadMessage;    Label1.Caption :=
SimpleIPCServer1.StringMessage;end;           
I have used the Object Inspector to create the event. Running two
instances, the first becomes the 'server' and the second becomes the
'client'. The client sends a message to the server. In practice, the
client does recognise that there is a server present, good, and
apparently sends it's message but the Server never responds.

Have I missed something ?  Documentation is a bit sparse but seems to
indicate thats all I need.  I am wondering if more modern forms of
Linux block what ever communication channel these components use ?
Likely given our interests in security. I can do the same thing with
DBus (only on linux) but it seems overkill if this simple approach
does work.

I have attached my minimalist project.

Davo

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winni · 2019-12-07 02:07

Hi!

Do you know the github demo page?

https://github.com/z505/SimpleIPC-lib/tree/master/demo-lazarus

Winni

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dsiders · 2019-12-07 02:11

Quote from: dbannon on December 07, 2019, 02:55:22 amHi Folks, I have
been playing with the two SimpleIPC components on the Lazarus System
Tab without any success. In its simplest form, here is what I am doing
-
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.FormShow(Sender: TObject);begin   
SimpleIPCClient1.ServerID:='tomboy-ng';   
SimpleIPCServer1.ServerID:='tomboy-ng';    if
SimpleIPCClient1.ServerRunning then begin        Label1.Caption := 'I
am a client';        SimpleIPCClient1.Active := true;       
SimpleIPCClient1.SendStringMessage('SHOWSEARCH');    end else begin  
    Label1.Caption := 'I am a server';       
SimpleIPCServer1.Global:=True;                  // anyone can connect 
      SimpleIPCServer1.Active := true;                // start
listening    end;end;                   procedure
TForm1.SimpleIPCServer1Message(Sender: TObject);begin   
SimpleIPCServer1.ReadMessage;    Label1.Caption :=
SimpleIPCServer1.StringMessage;end;           
I have used the Object Inspector to create the event. Running two
instances, the first becomes the 'server' and the second becomes the
'client'. The client sends a message to the server. In practice, the
client does recognise that there is a server present, good, and
apparently sends it's message but the Server never responds.

Have I missed something ?  Documentation is a bit sparse but seems to
indicate thats all I need.  I am wondering if more modern forms of
Linux block what ever communication channel these components use ?
Likely given our interests in security. I can do the same thing with
DBus (only on linux) but it seems overkill if this simple approach
does work.

I have attached my minimalist project.

Davo

Both client and server are used in units in:

components/chmhelp/lhelp/
tools/debugserver/

Should give a good representation of their usage.

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dbannon · 2019-12-07 02:53

Quote from: winni on December 07, 2019, 03:07:47 am... Do you know the
github demo page? .....

Thanks winin, no, did not know about it.   But they do not compile.
The client is an easy fix but the server seems to need something not
there. But maybe a look over the code will help.

@dsiders, also a good suggestion. If its used in lhelp, must still be
usable. I'll have a good poke around in there. Thanks.

Davo

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dbannon · 2019-12-07 08:05

OK, this does work as expected -

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.MessageQueued(Sender : TObject);begin   
SimpleIPCServer1.ReadMessage;    Label1.Caption :=
SimpleIPCServer1.StringMessage;end; procedure TForm1.FormShow(Sender:
TObject);begin    SimpleIPCClient1.ServerID:='tomboy-ng';   
SimpleIPCServer1.ServerID:='tomboy-ng';    if
SimpleIPCClient1.ServerRunning then begin        Label1.Caption := 'I
am a client';        SimpleIPCClient1.Active := true;       
SimpleIPCClient1.SendStringMessage('SHOWSEARCH');       
SimpleIPCClient1.Active := false;    end else begin       
Label1.Caption := 'I am a server';       
SimpleIPCServer1.OnMessageQueued:=@MessageQueued;       
SimpleIPCServer1.Global:=True;                  // anyone can connect 
      //SimpleIPCServer1.Active := true;       
SimpleIPCServer1.StartServer(True);             // start listening,
threaded    end;end;                  
Note two changes from my first attempt -
* To start the server we call 'StartServer', setting it to Active is
not the same thing !
* Don't use the Object Inspector to set a call back function. Just
pass SimpleIPCServer1.OnMessageQueued the address of the function you
want to call. I have no idea why .....

Thanks folks for pointing me in right direction. The demos in the fpc
source was particularly helpful, in my case
/usr/share/fpcsrc/3.0.4/packages/fcl-process/examples

Davo