Hallo,
I am using the ICS now for a long time, but there is one problem which I wasn't
able to solve.
Now I hope there is somebody outside, who can give me "illumination" ;-). I try
to explain this very detailled, sorry for the large mail.
I send many messages via SendStr. They can be very large (about 100KB each).
At first my implementation:
===========================================================================
I use a method called SendNext:
procedure Tnvc_AsyncBufferedClientSocket.SendNext;
begin
IF (osl_SendMessages.Count > oi_nextsend) THEN BEGIN
IF NOT ob_sending THEN BEGIN
ob_sending := TRUE;
oSock_Client.SendStr (osl_SendMessages.Strings[oi_nextsend]);
inc (oi_nextsend);
END {IF};
END ELSE
ob_sending := FALSE;
{END {IF};
end;
In the event OnDataSent I do the following:
procedure Tnvc_AsyncBufferedClientSocket.Socket_OnDataSent(Sender: TObject;
ErrCode: Word);
begin
ob_sending := FALSE;
SendNext;
end;
On the receiving side I use the DataAvailable event looking like this
procedure tnvc_DBGatewayServerClientConnection.ConnectionDataAvailable(Sender:
TObject; Error : Word);
VAR Buffer : array [0..4096] of char;
ls_receive, ls_msg:String;
li_rec:Integer;
li_msglen:Integer;
begin
li_rec := Receive (@Buffer, SizeOf(Buffer));
os_newMessage := copy (buffer,1, li_rec);
oi_len := oi_len + Length (os_newMessage);
os_Message := os_Message + os_newMessage;
//Process os_message
end;
===========================================================================
Now the problem:
If I am using this in a local network everything works fine. That means all
data which was sent will be received.
If I use this over the internet I lose many packets. And I don't know why.
As I thought the SendStr-procedure works with an internal buffer, which
guarantees that all messages which were sent will be received right on the
other side?
In an other implementation I do a "SendBlock". that means, I divide my Message
in tcp-Blocks (around 1400 Bytes per Block) and wait for an OnDataSent after
each block. This seems to work without losses.
The problem is, that I need to have the sending asyncron, means the application
has to handle incoming messages during sending, so I must implement my own
thread handling - this I would like to avoid.
I know, the description is a little bit confused, but I hope you understand my
problem and maybe you have own experiences how to implement a tcp-send/receive
where it is guaranteed that all messages which are sent will be received.
Thanks for any hints,
M;chael
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