public static final int ERR_SSN_SRVC = 0x02;

    // name service error codes
    public static final int FMT_ERR = 0x1;
    public static final int SRV_ERR = 0x2;
    public static final int IMP_ERR = 0x4;
    public static final int RFS_ERR = 0x5;
    public static final int ACT_ERR = 0x6;
    public static final int CFT_ERR = 0x7;

    // session service error codes
    public static final int CONNECTION_REFUSED    = -1; 

    }
  }

  private fun shouldIgnoreAndWaitForRealResponse(
    code: Int,
    exchange: Exchange,
  ): Boolean =
    when {
      // Server sent a 100-continue even though we did not request one. Try again to read the
      // actual response status.
      code == 100 -> true

      // Handle Processing (102) & Early Hints (103) and any new codes without failing
      // 100 and 101 are the exceptions with different meanings

The status codes in the 400 range mean that there was an error from the client.

Remember all those **"404 Not Found"** errors (and jokes)?

## Use `HTTPException`

To return HTTP responses with errors to the client you use `HTTPException`.

### Import `HTTPException`

```Python hl_lines="1"

///

## Schreiben des Codes, der den Callback dokumentiert

Dieser Code wird nicht in Ihrer Anwendung ausgeführt, wir benötigen ihn nur, um zu *dokumentieren*, wie diese *externe API* aussehen soll.

frontend-app@1.0.0 generate-client /home/user/code/frontend-app
> openapi-ts --input http://localhost:8000/openapi.json --output ./src/client --client axios
```

</div>

Dieser Befehl generiert Code in `./src/client` und verwendet intern `axios` (die Frontend-HTTP-Bibliothek).

### Den Client-Code ausprobieren

}

// STSError structure
type STSError struct {
	Code           string
	Description    string
	HTTPStatusCode int
}

// STSErrorResponse - error response format
type STSErrorResponse struct {
	XMLName xml.Name `xml:"https://sts.amazonaws.com/doc/2011-06-15/ ErrorResponse" json:"-"`
	Error   struct {
		Type    string `xml:"Type"`
		Code    string `xml:"Code"`
		Message string `xml:"Message"`
	} `xml:"Error"`

	return blobBody
}

// WriteHeader - writes http status code
func (lrw *ResponseRecorder) WriteHeader(code int) {
	if !lrw.headersLogged {
		lrw.ttfbHeader = time.Now().UTC().Sub(lrw.StartTime)
		lrw.StatusCode = code
		lrw.writeHeaders(&lrw.headers, code, lrw.ResponseWriter.Header())
		lrw.headersLogged = true
		lrw.ResponseWriter.WriteHeader(code)
	}
}

// Flush - Calls the underlying Flush.

* **Uvicorn**:
    * Bietet die beste Leistung, da außer dem Server selbst nicht viel zusätzlicher Code vorhanden ist.

    end

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Rick")
        function ->> execute: führe Code der Funktion aus
        execute ->> code: gib das Resultat zurück
    end

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Rick", salutation="Mr.")
        function ->> execute: führe Code der Funktion aus

import okhttp3.internal.connection.RealCall
import okio.Sink
import okio.Source

/** Encodes HTTP requests and decodes HTTP responses. */
interface ExchangeCodec {
  /** The connection or CONNECT tunnel that owns this codec. */
  val carrier: Carrier

  /** Returns an output stream where the request body can be streamed. */
  @Throws(IOException::class)
  fun createRequestBody(
    request: Request,
    contentLength: Long,
  ): Sink