Problem by subclassing the QIODevice

[wysota]

Isn't websocket data related to the tcp data you receive? I don't understand why do you want to mimic QAbstractSocket so much. Either you are dealing with low-level mechanism in which case what QTcpSocket offers is just enough or you want to implement a high-level mechanism (with access to all the headers and stuff) in which case you should probably just implement a backend for QNetworkAccessManager. WebSockets is an application layer concept and QAbstractSocket is a transport layer concept.

[erqsor]

Websockets is a transport layer too. You have to specify data type (binary, text, ...) and frame formats, size, mask, etc...
As I readed, QNetworkAccessManager can be used to send requests and receive answers, how can I etablish a socket connexion like this ?
In my case, I'm the server, I have requests to send, but not only, I have mainly requests to receive and treat.
Thats the aim of the websocket mechanism. Find a alternative to ajax polling by using sockets.

I don't know why do you want I change my architecture ? I just needed some informations on the QIODevice subclassing...

[wysota]

Websockets is a transport layer too. You have to specify data type (binary, text, ...) and frame formats, size, mask, etc...

So it's not a transport layer.

As I readed, QNetworkAccessManager can be used to send requests and receive answers, how can I etablish a socket connexion like this ?

By reimplementing QNetworkAccessManager::createRequest() and making the connection to the server.

I don't know why do you want I change my architecture ? I just needed some informations on the QIODevice subclassing...

I don't want to change your architecture. You are the one complaining about your current architecture. If you ask me, you can even derive your socket from QRect if you really like to do additional work.

[erqsor]

OK, I thought that was a transport layer.

I'm not closed to any suggestion, but here I don't understand how you can etablish the connexion.
In my case, the C++ application is on the server side, and the javascript web application is on the client side, and this web application send the first request.
So the first thing I have to do in the C++ application is to receive a request, and not send requests. How can you do that with QNetworkAccessManager::createRequest ?
Or do you have a turorial/example ?

[wysota]

OK, I thought that was a transport layer.

If I understand how WebSockets work, they make a request over HTTP which is above the transport layer (TCP serves as the transport layer).

I'm not closed to any suggestion, but here I don't understand how you can etablish the connexion.

Qt is open source, take a look there

In my case, the C++ application is on the server side, and the javascript web application is on the client side, and this web application send the first request.

Then I have totally no idea why you want to have a subclass of QAbstractSocket. You should have something similar to QTcpServer which is not derived from either QIODevice or QTcpSocket.

What you are implementing is a regular HTTP server serving regular HTTP requests. I don't know what your web application does but unless it tries to do arbitrary streaming over websocket API (which is doubtful) there is really no point in deriving anything from QAbstractSocket.

[erqsor]

If I understand how WebSockets work, they make a request over HTTP which is above the transport layer (TCP serves as the transport layer).

Yes, the client side is Google Chrome or Mozilla Firefox.
This client send the first HTTP request.
So by my side (server side), I have to get a client request (to etablish a connexion). And up to now, I used sockets to reply other requests.

You can read the ref here : http://tools.ietf.org/html/draft-iet...ketprotocol-17

Thats not "my" application. I'm making a generic API (webserver socket with Qt). So users can do simple requests or streaming, etc... (what they want...).
So for now, I give to my API users a QWsSocket with which they can communicate with different clients.

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Added after 13 minutes:

I looked this documentation (In French, sorry) http://qt.developpez.com/doc/4.7/qnetworkaccessmanager/
And they speak about requests sended by the server to receive replies.
But here I'm doing the opposite. So if you want, I could qnetworkaccessmanager if I had to developpe a client application, but here I need to develop a server application. Thats not the server which requests the clients, but clients which requests the server.

[wysota]

I'm making a generic API (webserver socket with Qt). So users can do simple requests or streaming, etc... (what they want...).
So for now, I give to my API users a QWsSocket with which they can communicate with different clients.

The thing is there is no benefit in returning a subclass of QAbstractSocket. Of course it is technically possible to do that however in my personal opinion it is better to deliver an object more similar to QNetworkReply --- something that contains the headers of the request and means to read the body of the request through QIODevice API.

I looked this documentation (In French, sorry) http://qt.developpez.com/doc/4.7/qnetworkaccessmanager/
And they speak about requests sended by the server to receive replies.
But here I'm doing the opposite.

Yes, I know. You can't use QNAM. When I was suggesting that I was under impression you were interested in the client side (because of your interest in QAbstractSocket instead of QTcpServer).

[erqsor]

OK, you say that I'm interested by the client side because I'm using sockets.
So you think I don't need sockets in my server application.
So I'm interested to know, when a connexion is etablished with a client by the QTcpServer, how do you send data to this client ?
personaly, I don't know how to do this without using the socket of this client...

[wysota]

OK, you say that I'm interested by the client side because I'm using sockets.

No. I thought you were interested in the client side because QAbstractSocket represents a client side of the connection. The server is implemented by Q*Server.

So I'm interested to know, when a connexion is etablished with a client by the QTcpServer, how do you send data to this client ?
personaly, I don't know how to do this without using the socket of this client...

I'm not saying you shouldn't be using sockets! I'm saying that you should give your users an API that more resembles QNetworkReply than QTcpSocket. Internally you will use a tcp socket but you shouldn't expose that socket to the outside world.

[erqsor]

OK, so can you tell me how can I replace my QTcpServer by a QNetworkReply ? The QtAssistant doesn't illustrate this case...
For now, I'm using the QTcpServer::listen function for waiting client connexions, and creating a QTcpSocket to communicate with this client.

[wysota]

OK, so can you say to me how can I replace my QTcpServer by a QNetworkReply ? The QtAssistant doesn't illustrate this case...
For now, I'm using the QTcpServer::listen function for waiting client connexions, and creating a QTcpSocket to communicate with this client.

Come on. Read my posts carefully, I never said you should replace QTcpServer with QNetworkReply.

[erqsor]

Ok, misunderstanding, sorry...

No. I thought you were interested in the client side because QAbstractSocket represents a client side of the connection. The server is implemented by Q*Server.

But I need sockets in server side ^^

Anyway, I wanted to do my API like this : The user uses these two ws objects (QWsServer, QWsSocket) as he uses these two tcp objects (QTcpServer, QTcpSocket).
The user don't use tcp objects: The TCP instructions are done in background (hidden).

As I said at begining, I have some problems :
- Inherit the QWsServer from QTcpServer : I can't because the newConnection signal is already used in background by the QTcpServer. And I can't offer this signal to the QWsServer users by inheritance.
- Inherit the QWsSocket from QTcpSocket : I can't for the same reason with the readyRead signal.

So I have not used inheritance, but aggregation (I don't know if thats the right word in English). So the QWsServer has a ptr to a QTcpServer as member. And the QWsSocket has a QTcpSocket ptr as member too.
QWsServer inherits from QObject and QWsSocket inherits from QAbstratSocket.
And finaly, for now I created my own signals and fonctions to read data in a QWsSocket, but I wanted to use the QAbstractSocket features to the fullest, and so reimplementing the common read functions and signals.

I hope what I said is clear !