I've just seen this post now. There is a Qt optimized cloud/BaaS alternative: you can look at V-Play Game Network: http://v-play.net/game-network/
Albeit its name, it is not only for games but also for apps.
See here for a list of useful components with their Qt API reference:
EDIT: OpenSSL problem had been caused by wrong framework (Qt 5.4.0 64bit) used to translate server app (with 32bit OpenSSL and 32bit client). Still I can't find the problem with the MAR instance. :-/ Localhost connection works only for ws:// Server app refuses connections via wss://
Actually, the errors in the console seem to indicate that the C++ API uses those chunks, and one of them failed to upload. Maybe there is no timeout, but an unstable connection.
If there is no retry mechanism on a chunk level, this will be very problematic in situations like the one we had to deal with. The land lines in South Africa really suck, and they tend to connect/disconnect a lot. I could built in a retry mechanism on the file level, but it almost never succeeds.
Can anyone give any insights on this? Is there a retry mechanism in place?