TZConnection (ZEOS) Timeout ?
lazarus / 16-Databases

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caused · 2011-06-02 12:28

Hi,
is there a simple way to add Timeout functionality to TZConnection.

IE. when connecting to an non existing server the default timeout is
around 20-30 seconds.

~caused

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JD · 2011-06-02 13:23

Use a timer (Lazarus has IdleTimer & Timer components).

a) Enable it in ZConnection1.BeforeConnect OR directly in a loop
before calling ZConnection1.Connect
b) As long as 20 - 30 secs have not elapsed, try to connect
c) If connection is still not possible after 20 - 30 secs, abort &
inform the user

Note that you have to catch the exception raised in (b) above with a
helpful message saying for example "Trying to connect to the database
...."

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caused · 2011-06-02 13:34

Hey JD,
the problem is, that the default timeout is around 20 -30 seconds,
which is MUCH too long.

So the timer method would probably not work ;/

~caused

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JD · 2011-06-02 14:50

Why don't you ping the server first before attemping to connect to it?

You are not the only one with this problem. It has already been
brought up on the Zeos forum

ZConnection hangs for nonexistent server
http://zeos.firmos.at/viewtopic.php?t=2454&highlight=timeout

Request TimeOut Value Property for ZConnection
http://zeos.firmos.at/viewtopic.php?t=1970&highlight=timeout

I always wrap my code in try....finally & try....except constructs to
avoid this problem & it works so far. For example

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 {----------
-------------------------------------------------------------------- 
Function: Connect-----------------------------------------------------
--------------------------}function TfrmMainform.Connect():
Boolean;begin  // Connect to the database  with
Datamodule1.ZConnection do  begin    try      Connect;     
IsConnected := True;    except      On E: Exception do      begin    
  IsConnected := False;        ShowMessage('Cannot connect to the
database at the moment. Please try again later.');      end;    end; 
end;  Result := IsConnected;end; With the code above, I get an
exception in about 5 - 7 seconds if a connection is not possible. I
can then proceed based on what the Connect function returns.

Remember that the speed of the network also comes into play here. The
faster the network, the quicker the response.

It is very basic but it works for me. But your mileage may vary...

JD

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nicke85 · 2011-06-04 11:14

this is part of code from one my aplication before try-except
statement
Code: [Select]with dbz.ZConnection1 do
                Begin
                Database:=Edit2.Text;
                HostName:=Edit1.Text;
                Password:=Edit4.Text;
                User:=Edit3.Text;
                Properties.Add('codepage=win1250');
                Properties.Add('client_encoding=win1250');
                Properties.Add('timeout=5');

it work on linux,win7 and winxp