[SOLVED] WebSockets client giving Access Violation
lazarus / 38-Networking and Web Programming

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Graham1 · 2023-12-14 22:49

I have downloaded the WebSockets files from
https://github.com/Warfley/LazWebsockets and tried using them. First I
amended the chatClient.pas line to be:

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   client :=
TWebsocketClient.Create('192.168.1.11', 8888);
Then I complied it (with Laz 2.0.12) and ran it on my Win10 64bit PC.
But I get an Access Violation error:

Code: Text  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i An
unhandled exception occurred at $0000000100001EC8:EAccessViolation:
Access violation  $0000000100001EC8  DESTROY,  line 93 of
chatClient.pas  $0000000100001E4F  CREATE,  line 89 of chatClient.pas 
$000000010000207A  main,  line 106 of chatClient.pas 
$00000001000020C6  main,  line 115 of chatClient.pas 
$0000000100010B20  $0000000100001840  $00007FF82D587344 
$00007FF82F1E26B1
I also tried the chatClient.html file having changed the line to:

Code: Javascript  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i     var
wsAddr = "ws://192.168.1.11:8888/";
and that ran fine, connecting and sending/receiving OK.

I tried breaking down the Create step into:

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 var 
client: TWebsocketClient;  sockHand : TSocketHandler;  sockComm :
TWebsocketCommunicator;  chat: TSimpleChat; BEGIN    writeln('Try
1');   try      client := TWebsocketClient.Create('192.168.1.11',
8888);   except      writeln('Error at 1');   end;    writeln('Try
2');   try      sockHand := TSocketHandler.Create;   except     
writeln('Error at 2');   end;    writeln('Try 3');   try      sockComm
:= client.Connect(sockHand);   except      writeln('Error at 3'); 
 end;    writeln('Try 4');   try      chat :=
TSimpleChat.Create(sockComm);   except      writeln('Error at 4'); 
 end;    chat.Free;   sockComm.Free;   sockHand.Free; 
 client.Free; END.
and I get the message 'Error at 4'. I then tried adding the line:

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  
 writeln(booltostr(sockComm.Open));
before the 'Try 4' line and it gave an error there too. So there seems
to be something wrong with creating the Communicator. I don't really
know where to start looking to fix this. Thanks!

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Graham1 · 2023-12-16 04:00

It seems the Master version is broken.

There is another message on this forum
(https://forum.lazarus.freepascal.org/index.php/topic,65547.0.html)
where user BlueIcaro was having a problem with his WebSockets client
program. I downloaded his project and found it opened and
sent/received OK. So I checked his program against mine and couldn't
see anything significant that was different until I thought of
comparing the main websocket library files. He seems to have fixed
them for the Access Violation error I was getting, or they are an
older version that used to work.

So my problem is fixed. But now I have the same problem as him....