val selection = routeSelector.next()
    dns.assertRequests(uriHost)
    val routes = selection.routes
    assertRoute(routes[0], address, Proxy.NO_PROXY, dns.lookup(uriHost, 0), uriPort)
    assertRoute(routes[1], address, Proxy.NO_PROXY, dns.lookup(uriHost, 1), uriPort)
    assertThat(selection.next()).isSameAs(routes[0])
    assertThat(selection.next()).isSameAs(routes[1])
    assertThat(selection.hasNext()).isFalse()

  val failedRoutes: Set<Route>
    @Synchronized get() = _failedRoutes.toSet()

  /** Records a failure connecting to [failedRoute]. */
  @Synchronized fun failed(failedRoute: Route) {
    _failedRoutes.add(failedRoute)
  }

  /** Records success connecting to [route]. */
  @Synchronized fun connected(route: Route) {
    _failedRoutes.remove(route)
  }

   *
   * 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,

  [entryPoints.http]
    address = ":9999"

[providers]
  [providers.file]
    filename = "routes.toml"
```

👉 💬 Traefik 👂 🔛 ⛴ 9️⃣9️⃣9️⃣9️⃣ & ⚙️ ➕1️⃣ 📁 `routes.toml`.

/// tip

👥 ⚙️ ⛴ 9️⃣9️⃣9️⃣9️⃣ ↩️ 🐩 🇺🇸🔍 ⛴ 8️⃣0️⃣ 👈 👆 🚫 ✔️ 🏃 ⚫️ ⏮️ 📡 (`sudo`) 😌.

///

🔜 ✍ 👈 🎏 📁 `routes.toml`:

```TOML hl_lines="5  12  20"
[http]
  [http.middlewares]

///

### Add the callback router { #add-the-callback-router }

At this point you have the *callback path operation(s)* needed (the one(s) that the *external developer*  should implement in the *external API*) in the callback router you created above.

Now use the parameter `callbacks` in *your API's path operation decorator* to pass the attribute `.routes` (that's actually just a `list` of routes/*path operations*) from that callback router:

[providers]
  [providers.file]
    filename = "routes.toml"
```

Esto le dice a Traefik que escuche en el puerto 9999 y que use otro archivo `routes.toml`.

/// tip | Consejo

Estamos utilizando el puerto 9999 en lugar del puerto HTTP estándar 80 para que no tengas que ejecutarlo con privilegios de administrador (`sudo`).

///

Ahora crea ese otro archivo `routes.toml`:

```TOML hl_lines="5  12  20"
[http]

[providers]
  [providers.file]
    filename = "routes.toml"
```

Isso diz ao Traefik para escutar na porta 9999 e usar outro arquivo `routes.toml`.

/// tip | Dica

Estamos usando a porta 9999 em vez da porta padrão HTTP 80 para que você não precise executá-lo com privilégios de administrador (`sudo`).

///

Agora crie esse outro arquivo `routes.toml`:

```TOML hl_lines="5  12  20"
[http]

## Benutzerdefinierte `APIRoute`-Klasse in einem Router

Sie können auch den Parameter `route_class` eines `APIRouter` festlegen:

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

* <a href="https://github.com/OAI/OpenAPI-Specification" class="external-link" target="_blank"><strong>OpenAPI</strong></a> pour la création d'API, incluant la déclaration de <abbr title="en français: routes. Aussi connu sous le nom anglais endpoints ou routes">path</abbr> <abbr title="Aussi connu sous le nom de méthodes HTTP. À savoir POST, GET, PUT, DELETE">operations</abbr>, paramètres, corps de requêtes, sécurité, etc.

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

## Clase personalizada `APIRoute` en un router

También puedes establecer el parámetro `route_class` de un `APIRouter`:

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