WebSockets over a 3G connection
I've been playing with Socket.io, node.js and WebSockets, all of which I can get working fine over a wifi connection.
However, when I test out a WebSocket-enabled app over a 3G connection (on my iPhone, for example) then it seems like falling back to long polling is the only workable solution.
With Socket.io the connection fails with "WebSocket connection invalid or Origin not verified" before falling back to long polling.
I don't know if WebSockets are meant to work over 3G - has anyone had success getting them to work like that? I've tried a number of different methods and the all seem to fail, which makes me think that I'm attempting the impossible.
Answer
Some mobile phone operators are notoriously known for setting up utterly broken transparent proxies that you're forced to pass through. This is a real annoyance that the WebSocket working group has had to deal with since the very beginning. The protocol is designed to ensure that it will fail very quickly in presence of such products so that your application can immediately fall back to other methods. If you find that it takes a long time to detect the anomaly and fall back, please report it to the hybi working group at the IETF so that the issue can be diagnosed and addressed.
In parallel, you can contact your mobile phone operator and ask them how you can access the net without passing through their broken transparent proxies or at least to know when they expect to get their broken proxies fixed to support HTTP according to specifications. Some of them might offer you multiple access options.