taskFaker.runTasks()
    client.listener.assertFailure(IOException::class.java, "source is closed")
    assertThat(client.webSocket!!.send("Hello!")).isFalse()
  }

  @Test
  fun socketClosedDuringMessageKillsWebSocket() {
    client2Server.source.close()
    assertThat(client.webSocket!!.send("Hello!")).isTrue()
    taskFaker.runTasks()
    client.listener.assertFailure(IOException::class.java, "source is closed")

    server.send(message3)
    clientListener.assertTextMessage(message3)

    // Empty client to server message.
    val message4 = ""
    client.send(message4)
    serverListener.assertTextMessage(message4)

    // Server to client message that shares context with message1.
    val message5 = message1 + message1
    server.send(message5)
    clientListener.assertTextMessage(message5)

            - application_state
            - receive
            - send
            - accept
            - receive_text
            - receive_bytes
            - receive_json
            - iter_text
            - iter_bytes
            - iter_json
            - send_text
            - send_bytes
            - send_json
            - close

  @Throws(IOException::class)
  fun connectionPreface() {
    this.withLock {
      if (closed) throw IOException("closed")
      if (!client) return // Nothing to write; servers don't send connection headers!
      if (logger.isLoggable(FINE)) {
        logger.fine(format(">> CONNECTION ${CONNECTION_PREFACE.hex()}"))
      }
      sink.write(CONNECTION_PREFACE)
      sink.flush()
    }
  }

This is normally called a **webhook**.

## 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.

  //   is interpreted as "data at least as new as the provided `resourceVersion`"
  //   and the bookmark event is send when the state is synced
  //   to a `resourceVersion` at least as fresh as the one provided by the ListOptions.
  //   If `resourceVersion` is unset, this is interpreted as "consistent read" and the
  //   bookmark event is send when the state is synced at least to the moment
  //   when request started being processed.

As you are sitting at the table with your crush, while you wait for the burgers, you can spend that time admiring how awesome, cute and smart your crush is ✨😍✨.

<img src="/img/async/concurrent-burgers/concurrent-burgers-05.png" class="illustration">

## Get the `username` and `password`

We are going to use **FastAPI** security utilities to get the `username` and `password`.

OAuth2 specifies that when using the "password flow" (that we are using) the client/user must send a `username` and `password` fields as form data.

And the spec says that the fields have to be named like that. So `user-name` or `email` wouldn't work.

## Await for messages and send messages

In your WebSocket route you can `await` for messages and send messages.

```Python hl_lines="48-52"
{!../../../docs_src/websockets/tutorial001.py!}
```

You can receive and send binary, text, and JSON data.

## Try it

If your file is named `main.py`, run your application with:

  override fun send(text: String): Boolean {
    return send(text.encodeUtf8(), OPCODE_TEXT)
  }

  override fun send(bytes: ByteString): Boolean {
    return send(bytes, OPCODE_BINARY)
  }

  @Synchronized private fun send(
    data: ByteString,
    formatOpcode: Int,
  ): Boolean {
    // Don't send new frames after we've failed or enqueued a close frame.