}
    )


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/items/": {
                "post": {
                    "responses": {
                        "200": {

    Note over client,operation: Response is already sent, can't change it anymore
    opt Tasks
        operation -->> tasks: Send background tasks
    end
    opt Raise other exception
        tasks -->> tasks: Handle exceptions in the background task code
    end
```

/// info

Only **one response** will be sent to the client. It might be one of the error responses or it will be the response from the *path operation*.

	}
	// Start processing requests.
	close(processHandler)

	// Drain responses
	got := 0
	for resp := range st.responses {
		// t.Log("got response", resp)
		errFatal(resp.Err)
		if resp.Msg[0] != byte(got) {
			t.Error("expected response", got, "got", resp.Msg[0])
		}
		got++
	}
	if got != 100 {
		t.Error("expected 100 responses, got", got)
	}
}

def test_openapi_schema(client: TestClient):
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/files/": {
                "post": {
                    "responses": {
                        "200": {

@needs_py39
def test_openapi_schema(client: TestClient):
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/files/": {
                "post": {
                    "responses": {
                        "200": {

```

////

Notice that the *path operations* define the models they use for request payload and response payload, using the models `Item` and `ResponseMessage`.

### API Docs

If you go to the API docs, you will see that it has the **schemas** for the data to be sent in requests and received in responses:

<img src="/img/tutorial/generate-clients/image01.png">

        writeTimeoutMillis = client.writeTimeoutMillis,
      )

    var calledNoMoreExchanges = false
    try {
      val response = chain.proceed(originalRequest)
      if (isCanceled()) {
        response.closeQuietly()
        throw IOException("Canceled")
      }
      return response
    } catch (e: IOException) {
      calledNoMoreExchanges = true
      throw noMoreExchanges(e) as Throwable
    } finally {

///

⚫️ ✔️ 🌐 ℹ 🔃 *➡ 🛠️* & ⚙️ 🏗 🏧 🧾.

⚫️ 🔌 `tags`, `parameters`, `requestBody`, `responses`, ♒️.

👉 *➡ 🛠️*-🎯 🗄 🔗 🛎 🏗 🔁 **FastAPI**, ✋️ 👆 💪 ↔ ⚫️.

/// tip

👉 🔅 🎚 ↔ ☝.

🚥 👆 🕴 💪 📣 🌖 📨, 🌅 🏪 🌌 ⚫️ ⏮️ [🌖 📨 🗄](additional-responses.md){.internal-link target=_blank}.

///

👆 💪 ↔ 🗄 🔗 *➡ 🛠️* ⚙️ 🔢 `openapi_extra`.

### 🗄 ↔

Wenn ein eingehender Request nicht korrekt validiert wird, wird eine „400“-Response gesendet.

## `GZipMiddleware`

Verarbeitet GZip-Responses für alle Requests, die `"gzip"` im `Accept-Encoding`-Header enthalten.

Diese Middleware verarbeitet sowohl Standard- als auch Streaming-Responses.

```Python hl_lines="2  6"
{!../../docs_src/advanced_middleware/tutorial003.py!}
```

        else if ( compound && this.nextCommand == 0 && this.readSize > 0 ) {
            // TODO: only apply this for actual compound chains, or is this correct for single responses, too?
            // 3.2.5.1.9 Handling Compounded Responses
            // The final response in the compounded response chain will have NextCommand equal to 0,
            // and it MUST be processed as an individual message of a size equal to the number of bytes