# Background Tasks - `BackgroundTasks`

You can declare a parameter in a *path operation function* or dependency function with the type `BackgroundTasks`, and then you can use it to schedule the execution of background tasks after the response is sent.

You can import it directly from `fastapi`:

```python
from fastapi import BackgroundTasks
```

```JSON
{"message": "Oops! yolo did something. There goes a rainbow..."}
```

/// note | "技術詳細"

また、`from starlette.requests import Request`と`from starlette.responses import JSONResponse`を使用することもできます。

**FastAPI** は開発者の利便性を考慮して、`fastapi.responses`と同じ`starlette.responses`を提供しています。しかし、利用可能なレスポンスのほとんどはStarletteから直接提供されます。これは`Request`と同じです。

///

## デフォルトの例外ハンドラのオーバーライド

**FastAPI** にはいくつかのデフォルトの例外ハンドラがあります。

    .build();

// Connect 'em all together. Certificates are exchanged in the handshake.
Call call = client.newCall(new Request.Builder()
    .url(server.url("/"))
    .build());
Response response = call.execute();
System.out.println(response.handshake().peerPrincipal());
RecordedRequest recordedRequest = server.takeRequest();
System.out.println(recordedRequest.getHandshake().peerPrincipal());
```

          "format": "time_series",
          "intervalFactor": 1,
          "range": true,
          "refId": "A"
        }
      ],
      "title": "Client Success Rate (non-5xx responses)",
      "type": "stat"
    },
    {
      "datasource": {
        "type": "prometheus",
        "uid": "${datasource}"
      },
      "fieldConfig": {
        "defaults": {
          "color": {

      val response =
        Response.Builder()
          .code(101)
          .message("OK")
          .request(Request.Builder().url(url).build())
          .headers(responseHeaders!!)
          .protocol(Protocol.HTTP_1_1)
          .build()
      webSocket =
        RealWebSocket(
          taskFaker.taskRunner,
          response.request,
          listener,
          random!!,

     * HttpServletResponse, byte[])} method to perform NTLM authentication
     * for the specified servlet request.
     *
     * @param req The request being serviced.
     * @param resp The response.
     * @param challenge The domain controller challenge.
     * @throws IOException If an IO error occurs.
     * @throws ServletException If an error occurs.
     */
    public NtlmPasswordAuthentication doAuthentication(

			ParentUser:   tmpCredentials.ParentUser,
		},
		UpdatedAt: updatedAt,
	}))

	response := new(AssumeRoleWithCustomTokenResponse)
	response.Result.Credentials = tmpCredentials
	response.Result.AssumedUser = parentUser
	response.Metadata.RequestID = w.Header().Get(xhttp.AmzRequestID)
	writeSuccessResponseXML(w, encodeResponse(response))

     * and well as their responses for each type however the actuall implementations
     * of the readXxxWireFormat and writeXxxWireFormat methods may not be in
     * place. For example at the time of this writing the readXxxWireFormat
     * for requests and the writeXxxWireFormat for responses are not implemented
     * and simply return 0. These would need to be completed for a server

         * with everything else. If the below clause evaluates true
         * the andx command will not be written and therefore the
         * response will not read a batched command and therefore
         * the 'received' member of the response object will not
         * be set to true indicating the send and sendTransaction
         * methods that the next part should be sent. This is a

     * 
     * This does not provide any actual downgrade protection if SMB1 is allowed.
     * 
     * It will also break connections with SMB2 servers that do not properly sign error responses.
     * 
     * @return whether to enforce the use of secure negotiation.
     */
    boolean isRequireSecureNegotiate ();


    /**
     * Enable port 139 failover
     *