Add documentation on muti-user with shared variables, broadcast_callback, ...

[FlorianJacta]

Description Add documentation on Shared variables and broadcasting mechanisms in the documentation.

Expected change An article could be created inside the Tutorials section as well as the User Manual.

[AlexandreSajus]

I propose we use this simple two-user chatbot that uses both broadcast and add_shared_variable:

• broadcast here is used to send the message to the other user
• add_shared_variable makes sure that when a new user connects, he sees the full conversation

from taipy.gui import Gui, State
import pandas as pd

timer_status = "Timer stopped"

client_index = 1
user_name = ""
conversation = pd.DataFrame(
    {"User": ["Alex", "Doppler"], "Message": ["Hey!", "Whats'up?"]}
)
current_message = ""
new_message = ""
new_sender = ""
selected_row = [2]

def on_init(state: State):
    global client_index
    if client_index == 1:
        state.user_name = "Alex"
    else:
        state.user_name = "Doppler"
    client_index += 1

# Start or stop the timer when the button is pressed
def send_message(state):
    state.broadcast("new_message", state.current_message)
    state.broadcast("new_sender", state.user_name)
    state.current_message = ""

def on_change(state, var_name, value):
    if var_name == "new_message":
        # Check if the last row is not already the user's message
        if (
            state.conversation.iloc[-1]["User"] != state.user_name
            or state.conversation.iloc[-1]["Message"] != state.new_message
        ):
            state.conversation = pd.concat(
                [
                    state.conversation,
                    pd.DataFrame(
                        {"User": [state.user_name], "Message": [state.new_message]}
                    ),
                ],
                ignore_index=True,
            )
        state.selected_row = [len(state.conversation["User"]) + 1]

page = """# Multi-User **Chat**{: .color-primary}

Username: <|{user_name}|input|active=false|>

<|{conversation}|table|rebuild|show_all|class_name=table|selected={selected_row}|>

<|{current_message}|input|label=Write your message here...|on_action=send_message|class_name=fullwidth|change_delay=-1|>
"""

gui = Gui(page)
gui.add_shared_variable("conversation")
gui.run(dark_mode=True)

I could take point on this. Where should this be in the doc? Should this be a "Fundamentals" tutorial about Multi-User capabilities? The user manual on broadcast and add_shared_variable could point to this tutorial.

EDIT: the tutorial should introduce the shared variable approach first

[jrobinAV]

@AlexandreSajus Are you working on that? Otherwise please unassign it. Thank you for your understanding.

[AlexandreSajus]

Yes, I am working on that currently. I was waiting for https://github.com/Avaiga/taipy/issues/1080 to be fixed first

[jrobinAV]

Great. Thx