[PATCH V2 uhttpd] ubus: add new RESTful API

[Rafał Miłecki]

On 31.07.2020 13:02, Andre Valentin wrote:
> this is really great stuff. It would help me to get forward with my wifi controller.
> Could it be possible to subsribe to multiple sources to limit the connections to ubus?
> 2 SSIDs with 2.4 ad 5GHz would me 4 concurrent channels if I understand right.

I'm happy someone finds it useful!

If you mean hostapd.* objects, that's right. That would require you to
use:
/ubus/subscribe/hostapd.wlan0
/ubus/subscribe/hostapd.wlan0-1
/ubus/subscribe/hostapd.wlan1
/ubus/subscribe/hostapd.wlan1-1

For subscribing to multiple objects we would need to:
1. Stick to GET due to the way EventSource works
2. Pick some more generic URL
3. Adjust output format ("event" and "data" fields)

So my guess would be something like:

$ curl http://192.168.1.1/ubus/subscribe?path=hostapd.wlan0&path=hostapd.wlan1
event: hostapd.wlan1 status
data: {"count":5}

event: hostapd.wlan0-1 status
data: {"count":5}

event: hostapd.wlan1 status
data: {"count":7}


Regarding parsing events stream, event names with spaces seem to be OK:
https://html.spec.whatwg.org/multipage/server-sent-events.html#parsing-an-event-stream
field value can use any scalar value other than line break char.

We should use some special character as separator of object name and
notification name. It must be something that ubus doesn't use in any of
them. Should space be OK? Or should we use some more fancy char? I
quickly tested space and it seems to work well in Firefox and Chromium.