```
https://yourapi.com/invoices/?callback_url=https://www.external.org/events
```

з JSON-тілом:

```JSON
{
    "id": "2expen51ve",
    "customer": "Mr. Richie Rich",
    "total": "9999"
}
```

тоді *ваш API* опрацює рахунок і згодом надішле запит зворотного виклику на `callback_url` ( *зовнішній API* ):

```
https://www.external.org/events/invoices/2expen51ve
```

з JSON-тілом на кшталт:

        // flush() delegates to expired(); with empty buffer, no-op (no exception)
        logNotificationTarget.flush();
    }

    @Test
    public void test_expired_withEvents_drainsBuffer() {
        // Add events to buffer
        ComponentUtil.getLogNotificationHelper()
                .offer(new LogNotificationEvent(System.currentTimeMillis(), "ERROR", "org.test", "msg1", null));
        ComponentUtil.getLogNotificationHelper()

## Événements envoyés par le serveur (SSE) { #server-sent-events-sse }

    - advanced/middleware.md
    - advanced/sub-applications.md
    - advanced/behind-a-proxy.md
    - advanced/templates.md
    - advanced/websockets.md
    - advanced/events.md
    - advanced/testing-websockets.md
    - advanced/testing-events.md
    - advanced/testing-dependencies.md
    - advanced/async-tests.md
    - advanced/settings.md
    - advanced/openapi-callbacks.md
    - advanced/openapi-webhooks.md

    yield ServerSentEvent(raw_data="<div>html fragment</div>", event="html")
    yield ServerSentEvent(raw_data="cpu,87.3,1709145600", event="csv")


router = APIRouter()


@router.get("/events", response_class=EventSourceResponse)
async def stream_events():
    yield {"msg": "hello"}
    yield {"msg": "world"}


app.include_router(router, prefix="/api")


@pytest.fixture(name="client")

https://yourapi.com/invoices/?callback_url=https://www.external.org/events
```

with a JSON body of:

```JSON
{
    "id": "2expen51ve",
    "customer": "Mr. Richie Rich",
    "total": "9999"
}
```

then *your API* will process the invoice, and at some point later, send a callback request to the `callback_url` (the *external API*):

```
https://www.external.org/events/invoices/2expen51ve
```

https://yourapi.com/invoices/?callback_url=https://www.external.org/events
```

com um corpo JSON de:

```JSON
{
    "id": "2expen51ve",
    "customer": "Mr. Richie Rich",
    "total": "9999"
}
```

então *sua API* processará a fatura e, em algum momento posterior, enviará um request de callback para o `callback_url` (a *API externa*):

```
https://www.external.org/events/invoices/2expen51ve
```

/// info | Informação

O exemplo acima é, na verdade, uma exceção, porque o objeto `io.BytesIO` já está em memória, então lê-lo não bloqueará nada.

Mas, em muitos casos, ler um arquivo ou um objeto semelhante a arquivo bloquearia.

///

    pass  # pragma: nocover


class Event(BaseModel):
    name: str
    total: float


events_callback_router = APIRouter()


@events_callback_router.get("{$callback_url}/events/{$request.body.title}")
def event_callback(event: Event):
    pass  # pragma: nocover


subrouter = APIRouter()


@subrouter.post("/invoices/", callbacks=invoices_callback_router.routes)

```
https://yourapi.com/invoices/?callback_url=https://www.external.org/events
```

並附上這個 JSON body：

```JSON
{
    "id": "2expen51ve",
    "customer": "Mr. Richie Rich",
    "total": "9999"
}
```

那麼「你的 API」會處理這張發票，並在稍後某個時點，向 `callback_url`（也就是「外部 API」）送出回呼請求：

```
https://www.external.org/events/invoices/2expen51ve
```

其 JSON body 大致包含：

```JSON
{