Read this section if you are interested in hacking on Bowtie or understanding how it works. Essentially, Bowtie works by using SocketIO to communicate between React and Python.

digraph foo { "Bowtie App" -> {"Browser 1";"Browser 2"} [dir="both",label=""]; bgcolor="transparent"; }


All the available components are associated with a React class. At a minimum each class must have a uuid and socket prop. The uuid prop is a unique identifier which is used to name the message being sent. The socket prop is a socketio connection.


Bowtie attempts to abstract away the Flask interface. Admittedly Flask is not difficult to learn but ultimately I wanted a library which required little boilerplate.

If you want to tinker with the Flask app, you can edit the file that gets generated during the build phase.


SocketIO binds the Python backend code to the React frontend. Python uses the Flask-SocketIO extension and the frontend uses


Almost every component has events associated with it. For example, a slider generates events when the user moves the slider. In Bowtie, these events are class properties with the prefix on_. With the App class you can subscribe callbacks to events, so when an event happens the callback is called with an argument that is related to the event.


Many components have commands to update their state. For example you can update the drop down list or update a plot. The commands are class functions that are prefixed do_. For example, to update a Plotly chart in Bowtie you can call do_all(dict), and Plotly will update it’s chart with the data and layout options defined in the dictionary.

Bowtie Application

There are a few key parts to any Bowtie application.

  1. Define the components in the app and any global state, e.g.:

    plotly = Plotly()
    dropdown = Dropdown(*config)
    global_dataset = SQLQuery(cool_data)
  2. Create what should happen in response to events:

    def callback(dropdown_item):
        # compute something cool and plot it
        data = cool_stuff(global_dataset, dropdown_item)
  3. Define the app and connect events to callbacks. I encourage using a function decorated with command:

    from bowtie import command
    def main():
        app = App(rows=1, columns=1, sidebar=True)
        app.subscribe(callback, dropdown.on_change)
        return app