in noVNC is there a way to receive String(a log) from the server which is not part of Frame(Screen)

Question

in noVNC there is a way to send a string from client to server using the api 'send_string' which is implemented inside websock.js, one thing i noticed is sending string this way is it is not RFB encoded(correct me if i am wrong), so the advantage in this case is commands can be send to intermediate proxy which intern connect to VNC server...

Now my query is .. is there a way for this intermediate proxy to send back some string back to vnc client... means it is not RFB encoded, so will be handled differently @ client

Thanks in advance

Answer 1

The websock.js library is the client-side part of the websockify project. The purpose of websockify is to bridge between WebSockets (which are message based) and normal TCP sockets (which are stream based).

The API that websock.js presents is a streaming API rather than a message based one. In addition, websockify/websock.js enables sending/receiving of binary data to the remote target even if the older WebSocket protocol (Hixie) is used which does not natively support binary data.

The send_string function is a convenience function so that you don't have to convert a string to an array form of the data before sending it. The data is still sent to the final target (it is not intercepted by websockify). The beginning of the RFB handshake is string based and so noVNC uses send_string in a couple of places (again, as a convenience).

If you want to have out-of-band communication between websock.js and websockify then you will need to modify both sides, perhaps by adding an initial byte to every message that indicates whether it is out-of-band signalling or part of the in-band stream. It is not builtin functionality.

Disclaimer: I made noVNC and websockify.