{* ../../docs_src/custom_request_and_route/tutorial002.py hl[16:18] *}

## Custom `APIRoute` class in a router { #custom-apiroute-class-in-a-router }

You can also set the `route_class` parameter of an `APIRouter`:

{* ../../docs_src/custom_request_and_route/tutorial003.py hl[26] *}

  /**
   * Invoked as soon as a call causes a connection to be started.
   */
  open fun connectStart(
    route: Route,
    call: Call,
  ) {}

  /**
   * Invoked when a connection fails to be established.
   */
  open fun connectFailed(
    route: Route,
    call: Call,
    failure: IOException,
  ) {}

  /**
   * Invoked as soon as a connection is successfully established.
   */

    try {
      user.connectStart(route)

      connectSocket()
      success = true
      return ConnectResult(plan = this)
    } catch (e: IOException) {
      // If we used the ProxySelector, and got a IOException during connect, report the failure.
      if (route.address.proxy == null && route.proxy.type() != Proxy.Type.DIRECT) {
        route.address.proxySelector.connectFailed(

   *
   * If [routes] is non-null these are the resolved routes (ie. IP addresses) for the connection.
   * This is used to coalesce related domains to the same HTTP/2 connection, such as `square.com`
   * and `square.ca`.
   */
  fun callAcquirePooledConnection(
    doExtensiveHealthChecks: Boolean,
    address: Address,
    connectionUser: ConnectionUser,
    routes: List<Route>?,
    requireMultiplexed: Boolean,

  /** Returns a plan for the first attempt at [route]. This throws if no plan is possible. */
  @Throws(IOException::class)
  internal fun planConnectToRoute(
    route: Route,
    routes: List<Route>? = null,
  ): ConnectPlan {
    if (route.address.sslSocketFactory == null) {
      if (ConnectionSpec.CLEARTEXT !in route.address.connectionSpecs) {
        throw UnknownServiceException("CLEARTEXT communication not enabled for client")

  }

  private fun assertRoute(
    route: Route,
    address: Address,
    proxy: Proxy,
    socketAddress: InetAddress,
    socketPort: Int,
  ) {
    assertThat(route.address).isEqualTo(address)
    assertThat(route.proxy).isEqualTo(proxy)
    assertThat(route.socketAddress.address).isEqualTo(socketAddress)
    assertThat(route.socketAddress.port).isEqualTo(socketPort)
  }

    }
  }

  override fun protocol(): Protocol = protocol

  override fun toString(): String =
    "Connection{${route.address.url.host}:${route.address.url.port}," +
      " proxy=${route.proxy}" +
      " hostAddress=${route.socketAddress}" +
      " cipherSuite=${handshake?.cipherSuite ?: "none"}" +
      " protocol=$protocol}"

  companion object {

  }

  override fun updateRouteDatabaseAfterSuccess(route: Route) {
    call.client.routeDatabase.connected(route)
  }

  override fun connectStart(route: Route) {
    eventListener.connectStart(call, route.socketAddress, route.proxy)
    poolConnectionListener.connectStart(route, call)
  }

  override fun connectFailed(
    route: Route,
    protocol: Protocol?,
    e: IOException,
  ) {

    override val timestampNs: Long,
    val route: Route,
    val call: Call,
  ) : ConnectionEvent()

  data class ConnectFailed(
    override val timestampNs: Long,
    val route: Route,
    val call: Call,
    val exception: IOException,
  ) : ConnectionEvent() {
    override fun closes(event: ConnectionEvent): Boolean = event is ConnectStart && call == event.call && route == event.route
  }

  data class ConnectEnd(

    // we should try the next route (if there is one).
    if (e is InterruptedIOException) {
      return e is SocketTimeoutException && !requestSendStarted
    }

    // Look for known client-side or negotiation errors that are unlikely to be fixed by trying
    // again with a different route.
    if (e is SSLHandshakeException) {