Medusa: [ FEATURE ] Add websockets

[OmgImAlexis]

If websockets were added then we could use them to update the page as new changes come along instead of having to rely on polling the server for new changes. This would also fix the get_messages spam that we currently have.

[p0psicles]

Do you have some examples? Or possibly docs for implementing it in python? I found this https://pypi.python.org/pypi/websockets, but that's min python 3.3

[OmgImAlexis]

Have a look at the docs for tornado, from what I can see there's already an implementation built in, you just need to use it like we already do with normal http requests.

www.tornadoweb.org/en/stable/websocket.html

[p0psicles]

Ooh cool! I'll see if I can replace the messages with this as a POC

[p0psicles]

How should we create the websocket route? Ive got something working using /ws/(.*). But maybe you also want to make this part of the versioned API?

[OmgImAlexis]

Maybe we just use /ws/ and then in the data we add in what it's for.

Like this and then we can just check if the message we get from the server has the event we need.

{
    "event": "notification",
    "data": {
        "title": "Test",
        "body": "This is a test notification!",
        "type": "message"
    }
}

[labrys]

@OmgImAlexis That sounds good. If in the future we find that its needed we can extend this to additional routes if needed, possibly even mirroring the APIv2 endpoints for route-specific websockets.

[p0psicles]

hmm just discovered that the ws is opened blocking other requests. Meaning it's running under the Tornado thread. But looping in the open() method like shown below, will not work. Maybe create a new thread specific for checking the ui messages?

class WebSocketUIHandler(WebSocketHandler):
    def check_origin(self, origin):
        return True

    def open(self, *args, **kwargs):
        clients.append(self)
        WebSocketHandler.open(self, *args, **kwargs)
        while True:
            messages = {}
            cur_notification_num = 1
            for cur_notification in notifications.get_notifications(self.request.remote_ip):
                messages['notification-' + str(cur_notification_num)] = {'title': cur_notification.title,
                                                                         'message': cur_notification.message,
                                                                         'type': cur_notification.type}
                cur_notification_num += 1
            if messages:
                self.write_message(messages)
            time.sleep(1)

    def on_message(self, message):
        print(u"Received: " + message)

    def data_received(self, chunk):
        WebSocketHandler.data_received(self, chunk)

    def on_close(self):
        clients.remove(self)

[OmgImAlexis]

@p0psicles I'd say open a new thread just for websockets since it'll need to run independently to the web ui.
This is if a new thread doesn't add more stress to the server?

[p0psicles]

Hmm. For what i've read, I have to remove any heavy processing from the handler, and move it to a separate thread. Meaning that the wshandler will only be called, when something has to be send over the socket. This means I have to at least get rid of the loop.

But the RequestHandler doesn't work like this. That one has a limited number of threads, that I can use for each request. I'd rather also have the websockets work like that.

[OmgImAlexis]

Would something like this not work? Since a websocket connection is kept open you should be able to just send anything through as a message and the browser should be able to receive it.

class WebSocketUIHandler(WebSocketHandler):
    def check_origin(self, origin):
        return True

    def open(self, *args, **kwargs):
        clients.append(self)
        messages = {}
        for cur_notification in notifications.get_notifications(self.request.remote_ip):
        self.write_message({
            'event': cur_notification.type,
            'data': {
                'title': cur_notification.title,
                'message': cur_notification.message
            }
        })

    def on_message(self, message):
        print(u"Received: " + message)

    def data_received(self, chunk):
        WebSocketHandler.data_received(self, chunk)

    def on_close(self):
        clients.remove(self)

[p0psicles]

[labrys]

Added to master feature request list - discussion for feature will continue here even though issue is closed.