Listening To Activities

An Activity is the Teams‑specific payload that flows between the user and your bot.
Where events describe high‑level happenings inside your app, activities are the raw Teams messages such as chat text, card actions, installs, or invoke calls.
The Teams AI Library v2 exposes a fluent router so you can subscribe to these activities with @app.event("activity").

Here is an example of a basic message handler:

@app.on_message
async def handle_message(ctx: ActivityContext[MessageActivity]):
    await ctx.send(f"You said '{ctx.activity.text}'")

In the above example, the ctx.activity parameter is of type MessageActivity, which has a text property. You'll notice that the handler here does not return anything, but instead handles it by sending a message back. For message activities, Teams does not expect your application to return anything (though it's usually a good idea to send some sort of friendly acknowledgment!).

Middleware pattern

The event activity handlers (and attributes) follow a middleware pattern similar to how python middlewares work. This means that for each activity handler, a next function is passed in which can be called to pass control to the next handler. This allows you to build a chain of handlers that can process the same activity in different ways.

@app.on_message
async def handle_message(ctx: ActivityContext[MessageActivity]):
    """Handle message activities using the new generated handler system."""
    print(f"[GENERATED onMessage] Message received: {ctx.activity.text}")
    await ctx.next()

@app.on_message
async def handle_message(ctx: ActivityContext[MessageActivity]):
    """Handle message activities using the new generated handler system."""
    if ctx.activity.text == "/help":
        await ctx.send("Here are all the ways I can help you...")
    await ctx.next()

@app.on_message
async def handle_message(ctx: ActivityContext[MessageActivity]):
    await ctx.send(f"You said '{ctx.activity.text}'")

info

Just like other middlewares, if you stop the chain by not calling next(), the activity will not be passed to the next handler. The order of registration for the handlers also matters as that determines how the handlers will be called.

Middleware pattern​

Middleware pattern