[Question] PubSub mechanism doesn't work when publishing to web..

[jjjunehkim]

Question

I have a problem while testing the operation of the PubSub mechanism.
When I run the Python script, it operates normally.
When I connect the files built with "flet build web" to the server (python -m http.server) and run a chat, messages cannot be sent to the other computer.
The code I tried is a sample code from the homepage (https://flet.dev/docs/cookbook/pub-sub/).

system environment
flutter : 3.24.2
flet : 0.24.1
OS : window11

Code sample

import flet as ft

def main(page: ft.Page):
    page.title = "Flet Chat"

    # subscribe to broadcast messages
    def on_message(msg):
        messages.controls.append(ft.Text(msg))
        page.update()

    page.pubsub.subscribe(on_message)

    def send_click(e):
        page.pubsub.send_all(f"{user.value}: {message.value}")
        # clean up the form
        message.value = ""
        page.update()

    messages = ft.Column()
    user = ft.TextField(hint_text="Your name", width=150)
    message = ft.TextField(hint_text="Your message...", expand=True)  # fill all the space
    send = ft.ElevatedButton("Send", on_click=send_click)
    page.add(messages, ft.Row(controls=[user, message, send]))

ft.app(main, view=ft.AppView.WEB_BROWSER)

Error message

No error messase. 
it just doesn't work

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• I have searched for answers to my question both in the issues and in previous discussions.