* response code like 404 or 500.
   *
   * @throws IOException if the request could not be executed due to cancellation, a connectivity
   *     problem or timeout. Because networks can fail during an exchange, it is possible that the
   *     remote server accepted the request before the failure.
   * @throws IllegalStateException when the call has already been executed.
   */
  @Throws(IOException::class)

 */
package okhttp3

import okio.IOException

interface Callback {
  /**
   * Called when the request could not be executed due to cancellation, a connectivity problem or
   * timeout. Because networks can fail during an exchange, it is possible that the remote server
   * accepted the request before the failure.
   */
  fun onFailure(
    call: Call,
    e: IOException,
  )

  /**

**This release introduces fast fallback to better support mixed IPv4+IPv6 networks.** Fast fallback
is what we're calling our implementation of Happy Eyeballs, [RFC 8305][rfc_8305]. With this
feature OkHttp will attempt both IPv6 and IPv4 connections concurrently, keeping whichever connects
first. Fast fallback gives IPv6 connections a 250 ms head start so IPv6 is preferred on networks
where it's available.

```Python hl_lines="9-13  36-53"
{!../../../docs_src/openapi_callbacks/tutorial001.py!}
```

!!! tip "Tipp"
    Der Query-Parameter `callback_url` verwendet einen Pydantic-<a href="https://docs.pydantic.dev/latest/api/networks/" class="external-link" target="_blank">Url</a>-Typ.

Das einzig Neue ist `callbacks=invoices_callback_router.routes` als Argument für den *Pfadoperation-Dekorator*. Wir werden als Nächstes sehen, was das ist.

      - [kops](#kops)
      - [Cluster Discovery/Bootstrap](#cluster-discoverybootstrap)
      - [Multi-platform](#multi-platform)
      - [Cloud Providers](#cloud-providers)
    - [Network](#network)
      - [network-policy](#network-policy)
      - [kube-proxy ipvs mode](#kube-proxy-ipvs-mode)
    - [API Machinery](#api-machinery)
      - [kube-apiserver](#kube-apiserver)

// ticket i/O GmbH : https://ticket.io
// Submitted by Christian Franke <******@****.***>
tickets.io

// Tlon.io : https://tlon.io
// Submitted by Mark Staarink <******@****.***>
arvo.network
azimuth.network
tlon.network

// Tor Project, Inc. : https://torproject.org
// Submitted by Antoine Beaupré <******@****.***
torproject.net
pages.torproject.net

/**
 * A concrete interceptor chain that carries the entire interceptor chain: all application
 * interceptors, the OkHttp core, all network interceptors, and finally the network caller.
 *
 * If the chain is for an application interceptor then [exchange] must be null. Otherwise it is for
 * a network interceptor and [exchange] must be non-null.
 */
class RealInterceptorChain(
  internal val call: RealCall,

  }

  @Test
  fun networkInterceptorsRewriteRequestToServer() {
    rewriteRequestToServer(true)
  }

  private fun rewriteRequestToServer(network: Boolean) {
    server.enqueue(MockResponse())
    addInterceptor(network) { chain: Interceptor.Chain ->
      val originalRequest = chain.request()
      chain.proceed(
        originalRequest.newBuilder()

  }

  companion object {
    /**
     * Cache control request directives that require network validation of responses. Note that such
     * requests may be assisted by the cache via conditional GET requests.
     */
    @JvmField
    val FORCE_NETWORK = commonForceNetwork()

    /**
     * Cache control request directives that uses the cache only, even if the cached response is

      context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager

    val network =
      connectivityManager.activeNetwork ?: throw AssumptionViolatedException("No active network")

    val client =
      OkHttpClient.Builder()
        .dns(AsyncDns.toDns(AndroidAsyncDns.IPv4, AndroidAsyncDns.IPv6))
        .socketFactory(network.socketFactory)
        .build()

    val call =