[Interest] Problem transfering bigger data amounts over Websockets on iOS

Jason H jhihn at gmx.com
Fri Jan 20 18:33:05 CET 2017

What about sending sending ping messages periodically?

Is your app being backgrounded? I had a problem with websockets disconnecting on iOS, but not on Android.

> Sent: Friday, January 20, 2017 at 5:58 AM
> From: "Markus Steinhilber" <markus.st.wrk at gmail.com>
> To: interest at qt-project.org
> Subject: [Interest] Problem transfering bigger data amounts over Websockets on iOS
> Hi,
> I currently have a problem with websockets on iOS. I'm using a
> websocket connection to send commands and files over a network (WiFi)
> between 2 devices. The server is a Windows CE device with Qt5.3 and
> the client can be an iPad or Windows PC, using a program compiled with
> Qt 5.7.1. The files are transfered by breaking them into smaller parts
> (~20-300KB, depending on the speed of the last part) and sending them
> as a websocket message. There is a small protocol implemented to
> coordinate the parts.
> Especially when transfering bigger files(>200MB) over the network, at
> some point i always run into a disconnect of the socket with the
> closeReason "Timeout when reading data from socket." on the Client.
> The server then gives a normal disconnect without closeReason.
> My first question is: Is this a normal closeReason for a disconnect in
> case of a bad WiFi connection or could it be a bug in my software or
> even in Qt's Websocket implementation? I did force some disconnects by
> powering off the server device while transfering data and I did not
> get the same error on the client.
> I also found the QTBUG-14975 which very much sounds like my issue. The
> closeReason is set in qwebsocketframe.cpp after a
> waitForReadyRead(5000). But the main differences are that this bug is
> only reported as happening on Windows and about every 4-5GB
> transmitted. In my case it's happening only on iOS and about every
> 200-300 MB.
> Since the problem only happens on iOS(iPad and simulator) but not with
> a Windows PC as client, i am also thinking about, if this could be an
> OS related problem. Like iOS detecting a Wifi disconnect earlier when
> a Windows PC maybe waits a bit longer and the connections get better
> again.
> Would it be a solution to change the timeout of the
> waitForReadyRead(5000) in qwebsocketframe.cpp and compile a custom Qt?
> Is it likely that this will help?
> Thanks for any help on that topic. I'm investigating this problem for
> days and don't find any solution.
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