# Server-Sent Events (SSE) { #server-sent-events-sse }

You can stream data to the client using **Server-Sent Events** (SSE).

This is similar to [Stream JSON Lines](stream-json-lines.md), but uses the `text/event-stream` format, which is supported natively by browsers with the [`EventSource` API](https://developer.mozilla.org/en-US/docs/Web/API/EventSource).

/// info

Added in FastAPI 0.135.0.

///

	maps.Copy(ntargets, list.targets)
	return ntargets
}

// Send - sends events to targets identified by target IDs.
func (list *TargetList) Send(event Event, id TargetID) (*http.Response, error) {
	list.RLock()
	target, ok := list.targets[id]
	list.RUnlock()
	if ok {
		return target.Send(event)
	}
	return nil, ErrARNNotFound{}
}

// Stats returns stats for targets.

This is normally called a **webhook**.

## Webhooks steps { #webhooks-steps }

The process normally is that **you define** in your code what is the message that you will send, the **body of the request**.

You also define in some way at which **moments** your app will send those requests or events.

    }

    /**
     * Calculate average send latency in microseconds
     *
     * @return average send latency
     */
    public double getAverageSendLatencyMicros() {
        long sends = rdmaSends.get();
        if (sends == 0) {
            return 0.0;
        }
        return totalSendTime.get() / (double) sends / 1000.0; // Convert to microseconds
    }

    /**

            RdmaMemoryRegion sendRegion = bufferManager.getSendRegion(4096);
            assertNotNull(sendRegion, "Send region should not be null");
            assertTrue(sendRegion.getSize() >= 4096, "Send region should be at least 4KB");
            assertNotNull(sendRegion.getBuffer(), "Send region buffer should not be null");

            RdmaMemoryRegion recvRegion = bufferManager.getReceiveRegion();

        byte[] data = "Appended".getBytes();

        // When
        outputStream.write(data);

        // Then - verify write request was sent
        verify(mockTreeHandle, atLeastOnce()).send(any(Smb2WriteRequest.class), any());
    }

    @Test
    void testMultipleWrites() throws IOException, CIFSException {
        // Given

# ----------------------------------------------------------
#                                                      Mail
#                                                     ------
# Does it send mock mail? (true: no send actually, logging only)
mail.send.mock = false

# SMTP server settings for main: host:port
mail.smtp.server.main.host.and.port = localhost:25

# The prefix of subject to show test environment or not

    with the API key and integrates that into the OpenAPI documentation. It extracts
    the key value sent in the query parameter automatically and provides it as the
    dependency result. But it doesn't define how to send that API key to the client.

    ## Usage

    Create an instance object and use that object as the dependency in `Depends()`.

            return message

        return inner

    async def __call__(self, scope, receive, send):
        if scope["type"] != "http" or self.max_content_size is None:
            await self.app(scope, receive, send)
            return

        wrapper = self.receive_wrapper(receive)
        await self.app(scope, wrapper, send)


@router.post("/middleware")

}

func (target *MQTTTarget) isActive() (bool, error) {
	if !target.client.IsConnectionOpen() {
		return false, store.ErrNotConnected
	}
	return true, nil
}

// send - sends an event to the mqtt.
func (target *MQTTTarget) send(eventData event.Event) error {
	objectName, err := url.QueryUnescape(eventData.S3.Object.Key)
	if err != nil {
		return err
	}
	key := eventData.S3.Bucket.Name + "/" + objectName