[Qt-interest] QTcpServer timeout ?

[BRM]

I believe you only have to do it on one side. QTcpServer won't have kind of 
support for this - nor should it; the support should go into 
QTcpSocket/QAbstractSocket if Nokia/Qt decides to do so.
AFAIK, it really doesn't matter which side sets up the Keep Alive; however, I 
would guess that most probably do so on the client-side.

Ben


>
>From: David Boosalis <david.boosalis at gmail.com>
>To: BRM <bm_witness at yahoo.com>
>Cc: QtInterest <qt-interest at trolltech.com>; aschmidt at dekaresearch.com
>Sent: Tue, July 20, 2010 5:47:03 PM
>Subject: Re: [Qt-interest] QTcpServer timeout ?
>
>BRM, Atlant.
>
>Thanks for your insight and feedback.  I read up on KeepAlive switch and it 
>basically does the polling for you without notifying your application as it is 
>doing so.  I think QTcpServer out to have methods for doing this.  But I was 
>able to do it with the following lines.
>
>
> int sockID = myQtSocket->socketDescriptor();
>  flag = 1;
>  ret = setsockopt( sockID, SOL_SOCKET, SO_KEEPALIVE, (char *)&flag, 
>sizeof(flag));
>
>
>One final question regarding KeepAlive. Should it be done on the server side or 
>client side, or does it not matter ?
>  
>
>
>
>On Tue, Jul 20, 2010 at 2:23 PM, BRM <bm_witness at yahoo.com> wrote:
>
>There is also another solution, though you may have to fall-back to some 
>platform specific code to enable it.
>>
>>Both Windows and Linux do have system level timers on the sockets. However, you 
>>can set a KEEP_ALIVE socket option.
>>While this can be specified on the socket creation (e.g. open()), it can also be 
>>set via the socket options (setsockopt() for Linux).
>>The KEEP_ALIVE option basically makes the operating system send the messages at 
>>the TCP protocol layer (per RFC 1122);
>>thus you don't have to generate or parse more messages or have to maintain a 
>>timer yourself to send them.
>>
>>http://en.wikipedia.org/wiki/Keepalive#TCP_Keepalive
>>http://tldp.org/HOWTO/TCP-Keepalive-HOWTO/usingkeepalive.html
>>http://msdn.microsoft.com/en-us/library/ms819735.aspx
>>
>>I could not quickly spot a way to get Qt to do this for you.
>>
>>HTH,
>>
>>Ben
>>
>>
>>>
>>>From: Atlant Schmidt <aschmidt at dekaresearch.com>
>>>To: David Boosalis <david.boosalis at gmail.com>; QtInterest 
>>><qt-interest at trolltech.com>
>>>Sent: Tue, July 20, 2010 4:01:13 PM
>>>Subject: Re: [Qt-interest] QTcpServer timeout ?
>>>
>>>
>>>
>>>David:
>>> 
>>>  It’s quite common for TCP connections of all sorts to have an inactivity 
>>>timer.
>>>  This is especially true if your session connects through a firewall or a 
>>>“public”
>>>  medium.
>>> 
>>>  Because you often can’t affect the settings of the various inactivity 
timers
>>>  you may encounter along the way, the usual solution is, as you surmised,
>>>  the use of keep-alive messages. I’m thinking that every five minutes is
>>>  too long, but that will depend on your particular circumstances.
>>> 
>>>                                    Atlant
>>> 
>>>
________________________________
 
>>>From:qt-interest -bounces at trolltech.com [mailto: qt-interest 
>>>-bounces at trolltech.com] On Behalf Of David Boosalis
>>>Sent: Tuesday, July 20, 2010 3:51 PM
>>>To: QtInterest
>>>Subject: [Qt-interest] QTcpServer timeout ?
>>> 
>>>I have Qt Client applications establishing  connections to server apps based 
>>>using QtTcpServer(s).  The sockets that send data quite often  have no problem 
>>>staying connected all day.  However the sockets that send notices maybe one 
>>>every two hours or perhaps just once a day tend to die. I never see a 
>>>disconnect, but the socket just seems to go to sleep as data fails to arrive to 
>>>the server.  I  was wondering if a time out occurring due to  the lack of 
>>>activity going across the socket.  I looked at the QTcpServer class for a method 
>>>that might turn off such a timer but did not see any.  Perhaps this behaviour 
>>>goes beneath QT and into the  Linux Tcp  Server design. If so is there a low 
>>>level call I can make on the socket ID to keep the connection always alive.  I 
>>>am thinking about sending a ping every 5 minutes on these sockets.  
>>>
>>>
>>>Any advise on how best to fix this time out is very much appreciated.
>>>
>>>-David
>>>
>>>
>>>
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