/** Writes the content of this request to [sink]. */
  @Throws(IOException::class)
  abstract fun writeTo(sink: BufferedSink)

  /**
   * A duplex request body is special in how it is **transmitted** on the network and
   * in the **API contract** between OkHttp and the application.
   *
   * This method returns false unless it is overridden by a subclass.
   *
   * ### Duplex Transmission
   *

6. Here we are returning a dictionary that contains `items` which is a list of dataclasses.

    FastAPI is still capable of <abbr title="converting the data to a format that can be transmitted">serializing</abbr> the data to JSON.

7. Here the `response_model` is using a type annotation of a list of `Author` dataclasses.

    Again, you can combine `dataclasses` with standard type annotations.

     */
    fun cacheUrlOverride(cacheUrlOverride: HttpUrl?) =
      apply {
        this.cacheUrlOverride = cacheUrlOverride
      }

    /**
     * Configures this request's body to be compressed when it is transmitted. This also adds the
     * 'Content-Encoding: gzip' header.
     *
     * Only use this method if you have prior knowledge that the receiving server supports
     * gzip-compressed requests.
     *

	resourceMetricsHelpMap = map[MetricName]string{
		interfaceRxBytes:  "Bytes received on the interface in " + interval,
		interfaceRxErrors: "Receive errors in " + interval,
		interfaceTxBytes:  "Bytes transmitted in " + interval,
		interfaceTxErrors: "Transmit errors in " + interval,
		total:             "Total memory on the node",
		memUsed:           "Used memory on the node",

    This should make it easier to use OkHttp in Gradle plugins.

 *  Fix: Don't start the clock on response timeouts until the request body is fully transmitted.
    This is only relevant for duplex request bodies, because they are written concurrently when
    reading the response body.

    )
    val read = response1.body.source().read(ByteArray(8192))
    assertThat(read).isEqualTo(8192)

    // Make a second call that should transmit the response headers. The response body won't be
    // transmitted until the flow-control window is updated from the first request.
    val call2 = client.newCall(Request(server.url("/")))
    val response2 = call2.execute()
    assertThat(response2.code).isEqualTo(200)

{* ../../docs_src/custom_response/tutorial006c_py39.py hl[2,7,9] *}

### `StreamingResponse` { #streamingresponse }

Toma un generador `async` o un generador/iterador normal y transmite el cuerpo del response.

{* ../../docs_src/custom_response/tutorial007_py39.py hl[2,14] *}

#### Usando `StreamingResponse` con objetos similares a archivos { #using-streamingresponse-with-file-like-objects }

Por exemplo, se você tivesse uma sessão de banco de dados em uma dependência com `yield`, o `StreamingResponse` não conseguiria usar essa sessão enquanto transmite dados, porque a sessão já teria sido fechada no código de saída após o `yield`.

Esse comportamento foi revertido na versão 0.118.0, para que o código de saída após o `yield` seja executado depois que a resposta for enviada.

Isso ainda é verdade.

Então, para poder ter **vários processos** ao mesmo tempo, tem que haver um **único processo escutando em uma porta** que então transmite a comunicação para cada processo de trabalho de alguma forma.

### Memória por Processo { #memory-per-process }