[Development] Qt WebChannel 5.5 roadmap: WebEngine, QtWebView

[Jocelyn Turcotte]

On Wed, Aug 27, 2014 at 04:27:35PM +0200, Milian Wolff wrote:
> Hey all,
> 
> for Qt 5.4, the new WebChannel module will only be "easily" usable for WebKit 
> users. For 5.5 I plan to add WebEngine integration, if Pierre is not beating 
> me to it. We will simply copy the QML API, and no changes on the client-side 
> HTML should be required, I think.
> 
> Then, recently, QtWebView was announced for Android and iOS WebViews. I wonder 
> if we can integrate the WebChannel nicely there as well. Instantiating a 
> WebChannel internally won't be the problem, nor copying the QML API. But for 
> HTML clients, I don't know if one can automatically setup the transport 
> mechanism (based on WebSockets), nor whether one can even load the 
> qwebchannel.js API via a qrc URL. Can someone working on QtWebView shed some 
> light here please? 

One thing that WebSockets do is that they are a transport layer on top of
HTTP. You can transport your qwebchannel.js or any html hook through a
non-upgraded WebSocket's HTTP response.

QtWebSocket doesn't support this at the moment and simply ignores any HTTP
request not asking for an upgrade, but I had a simple change that was
manually writing the HTTP response on the QTcpSocket and it worked pretty well.

The main issue is that you normally have websocket as part of an HTTP
server and not the other way around, so we'd have to stretch the API a
bit. I was able to hack it quickly by reusing QNetworkRequest and
QNetworkReply but we should probably duplicate their interface into some
kind of QWebSocketHttpRequest/Reply if we don't want to poison
QNetworkAccessManager's API with foreign use cases.

Cheers,
Jocelyn