A simple question of lNet
lazarus / 38-Networking and Web Programming

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senglit · 2020-06-10 14:01

Hi all,

What happen when I send a "TCP.SendMessage(string,TCP.Iterator)" 
while  "not (ssCanSend in TCP.Iterator.SocketState)"?
The message will be dumped or it will be added into a queue and send
when ssCanSend  ok? Or it will wait there untill ssCanSend is true and
send message?

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MarkMLl · 2020-06-10 14:12

You might be better asking at https://github.com/almindor/lnet

Note warning at https://wiki.freepascal.org/lNet#Overview

I'd love it if this package were better supported, since I think that
basic network protocols are so pervasive these days that they're worth
having in the standard libraries. I'm using the Telnet stuff in a
couple of places, and to be honest the /only/ thing to be said for it
is that it doesn't introduce an external dependency; I'm seriously
considering replacing it with a state machine which could sit on top
of whatever means of socket access best suits the remainder of the
program.

MarkMLl

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rvk · 2020-06-10 14:40

Maybe I don't see the point...

But isn't it so that this won't send anything????
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 while not
(ssCanSend in TCP.Iterator.SocketState) do 
TCP.SendMessage(string,TCP.Iterator);
It will only do the loop while ssCanSend is NOT in
TCP.Iterator.SocketState.

And isn't SendMessage not 'blocking'.
So it will try to send the message for a timeout time.
And if it fails halfway through it will return the number of bytes
really send.

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senglit · 2020-06-14 11:07

Quote from: rvk on June 10, 2020, 04:40:14 pmAnd isn't SendMessage not
'blocking'.
So it will try to send the message for a timeout time.
And if it fails halfway through it will return the number of bytes
really send.

I think you are right. Since SendMessage is a function which return an
integer, it must wait there till it knows if data are sent or not. If
the data are put in a queue and sent when ssCanSend is OK, the
function can not give that integer result.

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MarkMLl · 2020-06-14 11:57

Quote from: senglit on June 14, 2020, 01:07:11 pmI think you are
right. Since SendMessage is a function which return an integer, it
must wait there till it knows if data are sent or not. If the data are
put in a queue and sent when ssCanSend is OK, the function can not
give that integer result.

The TMyClass.OnCanSend() example at
https://lnet.wordpress.com/usage/sockets-protocols-and-sending/ shows
the way of sending recommended by lNet's author, and specifically
allows that SendMessage() might return zero if nothing can be sent.

MarkMLl