Supporting websockets through eventlet's wsgi server

[adamlwgriffiths]

I've managed to get python-socketio / flask-socketio working via the eventlet server and some monkey patching.

I've created a Gist with a self-contained demo of it.

What it boils down to is changing how webview.serving.get_wsgi_server wraps the provided function.

I think we could change how pywebview detects/runs the backend server to make this a better supported option.

Perhaps the get_wsgi_server should take an optional function that does the wrapping for you.

Something like:

def get_wsgi_server(app, run_func=None):
    def default_run_func(app, host, port):
        server = wsgiref.simple_server.make_server(
            'localhost', port, app, server_class=ThreadingWSGIServer,
            handler_class=WSGIRequestHandler11,
        )
    ...

    if not run_func:
        run_func = default_run_func

    t = threading.Thread(target=run_server, args=(app, 'localhost', port))
    ....

The issue is when calling webview.create_window('Title', my_run_function) it will match the existing if callable(url) check in webview.serving.resolve_url.
So I suspect you may need to add another parameter, say run_func to this function, and pass both to get_wsgi_server.

Ie.

def run_server(app, host, port):
    import eventlet
    import eventlet.wsgi
    eventlet.wsgi.server(eventlet.listen((host, port)), app)

app = ...

pywebview.create_window('Test', app, run_func=run_server)

Alternatively, we could look to change the check of the app variable in resolve_url.