Dash + AioHTTP?

Dash Python
1

is it possible to just set the dash.server instance to an aiohttp?

I read that it is based on flask, but flask isn’t suitable for production/etc. I’m using aiohttp for a graphql subscription server / api that is then working with IOT devices so… flask isn’t entirely suitable. However, I’d like to use dash with this.

Thanks

2

flask is suitable for production if you run it with gunicorn. In any case, you probably won’t be able to swap in aiohttp as a replacement for flask but you could write an alternative dash backend that uses aiohttp if you want.

I recommend looking through the source code of Dash to learn more: dash/dash/dash.py at 3cd6a78ee21620c77ccdbdf2724c995872383666 · plotly/dash · GitHub

3

Oblivious to this thread I have taken a stab at the topic due to my app’s demand (one part of my app generates data via asyncio/aiohttp and another needs to visualise and update based on a DataFrame).

Here’s a partially working example:

from asyncio import get_event_loop
from aiohttp.web import AppRunner, Application, Response, TCPSite, get
from aiohttp_wsgi import WSGIHandler
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Output,Input
from dash import Dash
from numpy.random import rand

def graph_figure():
    print(rand(5))
    return {'data':   [{'x': rand(5), 'y': rand(5), 'type': 'bar', 'name': 'SF'}],
            'layout': {'title': 'Test'}
            }

app = Dash('Orderbook')

def layout():
    return html.Div(children=[
    dcc.Graph(id='example-graph',
              figure=graph_figure()
             ),

    html.Button(
            'Submit',
            id='button'),

    dcc.Interval(
            id='interval-component',
            interval=1*1000, # in milliseconds
            n_intervals=0
            )
    ])

app.layout = layout

@app.callback(Output('example-graph', 'figure'), [Input('button', 'n_clicks'), Input('interval-component', 'n_intervals')])
def update_graph(n, n2):
    return graph_figure()

server = Application()
runner = AppRunner(server)

async def start_webapp() -> None:
    wsgi_handler = WSGIHandler(app.server)
    server.router.add_route('get', '/{path_info:.*}', wsgi_handler)
    await runner.setup()
    await TCPSite(runner, 'localhost', 8080).start()

if __name__ == '__main__':
    # app.run_server() # THIS WORKS

    # THIS DOES NOT WORK:
    loop = get_event_loop()
    loop.run_until_complete(start_webapp())
    loop.run_forever()

This generates and serves a plot, however updates via Interval and Button components do not work - the callback is not called.
Does anybody have any neat ideas how to force the callback trigger? Or should I come to terms with a static plot?