# Background Tasks { #background-tasks }

You can define background tasks to be run *after* returning a response.

This is useful for operations that need to happen after a request, but that the client doesn't really have to be waiting for the operation to complete before receiving the response.

This includes, for example:

* Email notifications sent after performing an action:

   *
   * ### Duplex Transmission
   *
   * With regular HTTP calls the request always completes sending before the response may begin
   * receiving. With duplex the request and response may be interleaved! That is, request body bytes
   * may be sent after response headers or body bytes have been received.
   *
   * Though any call may be initiated as a duplex call, only web servers that are specially

## API Response

XML response for this API is similar to [AWS STS AssumeRoleWithWebIdentity](https://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRoleWithWebIdentity.html#API_AssumeRoleWithWebIdentity_ResponseElements)

## Example request and response

Sample request with `curl`:

```sh

import org.codelibs.fess.util.RenderDataUtil;
import org.dbflute.optional.OptionalEntity;
import org.dbflute.optional.OptionalThing;
import org.lastaflute.web.Execute;
import org.lastaflute.web.response.HtmlResponse;
import org.lastaflute.web.response.render.RenderData;
import org.lastaflute.web.ruts.process.ActionRuntime;

import jakarta.annotation.Resource;

/**
 * Admin action for Web Config management.
 *
 */

import org.codelibs.fess.suggest.request.Response;

/**
 * Represents the response for popular words request.
 */
public class PopularWordsResponse implements Response {

    /**
     * The index associated with the response.
     */
    protected final String index;

    /**
     * The time taken to generate the response in milliseconds.
     */
    protected final long tookMs;

import org.codelibs.fess.app.web.api.admin.FessApiAdminAction;
import org.codelibs.fess.opensearch.config.exentity.RequestHeader;
import org.lastaflute.web.Execute;
import org.lastaflute.web.response.JsonResponse;

import jakarta.annotation.Resource;

/**
 * API action for admin request header management.
 *
 */
public class ApiAdminReqheaderAction extends FessApiAdminAction {

import org.codelibs.fess.app.web.api.admin.FessApiAdminAction;
import org.codelibs.fess.opensearch.config.exentity.WebAuthentication;
import org.lastaflute.web.Execute;
import org.lastaflute.web.response.JsonResponse;

import jakarta.annotation.Resource;

/**
 * API action for admin web authentication management.
 *
 */
public class ApiAdminWebauthAction extends FessApiAdminAction {

import org.codelibs.fess.helper.PermissionHelper;
import org.codelibs.fess.opensearch.config.exentity.AccessToken;
import org.codelibs.fess.util.ComponentUtil;
import org.lastaflute.web.Execute;
import org.lastaflute.web.response.JsonResponse;

/**
 * API action for admin access token.
 *
 */
public class ApiAdminAccesstokenAction extends FessApiAdminAction {

    /**
     * Default constructor.
     */

      @Override public void onFailure(Call call, IOException e) {
      }

      @Override public void onResponse(Call call, Response response) throws IOException {
        try (ResponseBody body = response.body()) {
          // Consume and discard the response body.
          body.source().readByteString();
        }
      }
    });

    Request newYorkTimesRequest = new Request.Builder()

  override fun peek(): MockResponse = throw UnsupportedOperationException("unexpected call")

  fun enqueueResponse(response: MockResponse) {
    delegate.enqueue(response.wrap())
  }

  override fun shutdown() {
    delegate.close()
  }

  fun setFailFast(failFast: Boolean) {
    delegate.setFailFast(failFast)
  }