## Die normale **FastAPI**-Anwendung

Sehen wir uns zunächst an, wie die normale API-Anwendung aussehen würde, bevor wir den Callback hinzufügen.

Sie verfügt über eine *Pfadoperation*, die einen `Invoice`-Body empfängt, und einen Query-Parameter `callback_url`, der die URL für den Callback enthält.

func TestCallbacks(t *testing.T) {
	type callback struct {
		name    string
		before  string
		after   string
		remove  bool
		replace bool
		err     string
		match   func(*gorm.DB) bool
		h       func(*gorm.DB)
	}

	datas := []struct {
		callbacks []callback
		err       string
		results   []string
	}{
		{
			callbacks: []callback{{h: c1}, {h: c2}, {h: c3}, {h: c4}, {h: c5}},

    private final CoreExtensionEntry extension;
    private final Function<String, String> callback;
    private final DefaultInterpolator interpolator = new DefaultInterpolator();

    public ExtensionConfigurationModule(CoreExtensionEntry extension, Function<String, String> callback) {
        this.extension = extension;
        this.callback = callback;
    }

    @Override
    public void configure(Binder binder) {

  override fun query(
    hostname: String,
    callback: AsyncDns.Callback,
  ) {
    try {
      resolver.query(
        network,
        hostname,
        dnsClass.type,
        DnsResolver.FLAG_EMPTY,
        executor,
        null,
        object : DnsResolver.Callback<List<InetAddress>> {
          override fun onAnswer(
            addresses: List<InetAddress>,

      Class<Throwable> exceptionType,
      Function<? super Throwable, ? extends V> fallback,
      Executor executor) {
    return (FluentFuture<V>) Futures.catching(this, exceptionType, fallback, executor);
  }

  public final FluentFuture<V> catchingAsync(
      Class<Throwable> exceptionType,
      AsyncFunction<? super Throwable, ? extends V> fallback,
      Executor executor) {

      Function<? super Throwable, ? extends V> fallback,
      Executor executor) {
    return AbstractCatchingFuture.create(input, exceptionType, fallback, executor);
  }

  public static <V extends @Nullable Object> ListenableFuture<V> catchingAsync(
      ListenableFuture<? extends V> input,
      Class<Throwable> exceptionType,
      AsyncFunction<? super Throwable, ? extends V> fallback,
      Executor executor) {

authorize_url = "http://localhost:8080/auth/realms/minio/protocol/openid-connect/auth"
token_url = "http://localhost:8080/auth/realms/minio/protocol/openid-connect/token"

# callback url specified when the application was defined
callback_uri = "http://localhost:8000/oauth2/callback"

# keycloak id and secret
client_id = 'account'
client_secret = 'daaa3008-80f0-40f7-80d7-e15167531ff0'

sts_client = boto3.client(
    'sts',

import mockwebserver3.MockWebServer
import org.junit.jupiter.api.Test

class DispatcherCleanupTest {
  @Test
  fun testFinish(server: MockWebServer) {
    val okhttp = OkHttpClient()
    val callback =
      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {}

        override fun onResponse(
          call: Call,
          response: Response,
        ) {

    dispatcher.maxRequests = 2
    client.newCall(newRequest("http://a/1")).enqueue(callback)
    client.newCall(newRequest("http://b/1")).enqueue(callback)
    client.newCall(newRequest("http://c/1")).enqueue(callback)
    client.newCall(newRequest("http://a/2")).enqueue(callback)
    client.newCall(newRequest("http://b/2")).enqueue(callback)
    dispatcher.maxRequests = 4

        UserCQ cq = new UserCQ();
        queryLambda.callback(cq);
        final Collection<FilterFunctionBuilder> list = new ArrayList<>();
        if (functionsLambda != null) {
            functionsLambda.callback((cqLambda, scoreFunctionBuilder) -> {
                UserCQ cf = new UserCQ();
                cqLambda.callback(cf);
                list.add(new FilterFunctionBuilder(cf.getQuery(), scoreFunctionBuilder));