# Seguridad - Primeros pasos { #security-first-steps }

Imaginemos que tienes tu API de **backend** en algún dominio.

Y tienes un **frontend** en otro dominio o en un path diferente del mismo dominio (o en una aplicación móvil).

Y quieres tener una forma para que el frontend se autentique con el backend, usando un **username** y **password**.

Podemos usar **OAuth2** para construir eso con **FastAPI**.

import okhttp3.mockwebserver.MockResponse;
import okhttp3.mockwebserver.MockWebServer;
import okhttp3.mockwebserver.RecordedRequest;
import okio.ByteString;

/**
 * Runs a MockWebServer on localhost and uses it as the backend to receive an OAuth session.
 *
 * <p>Clients should call {@link #start}, {@link #newAuthorizeUrl} and {@link #close} in that order.
 * Clients may request multiple sessions.
 */

In this guide, you'll learn how to generate a **TypeScript SDK** for your FastAPI backend.

## Open Source SDK Generators { #open-source-sdk-generators }

import org.lastaflute.web.validation.Required;

/**
 * Form for uploading files to the storage system via the admin API.
 * This form is used in the admin API interface to upload files to the storage backend
 * with optional path specification for file organization.
 */
public class UploadForm {

    /**
     * The storage path where the file should be uploaded.

[build-system]
requires = ["pdm-backend"]
build-backend = "pdm.backend"

[project]
name = "fastapi"
dynamic = ["version"]
description = "FastAPI framework, high performance, easy to learn, fast to code, ready for production"
readme = "README.md"
license = "MIT"
license-files = ["LICENSE"]
requires-python = ">=3.9"
authors = [
    { name = "Sebastián Ramírez", email = "******@****.***" },
]
classifiers = [

You could easily use a search engine or video platform to find many resources related to FastAPI.

/// info

Before, this page used to list links to external articles.

But now that FastAPI is the backend framework with the most GitHub stars across languages, and the most starred and used framework in Python, it no longer makes sense to attempt to list all articles written about it.

///

## GitHub Repositories

    if (isLoom()) {
      val backend = TaskRunner.RealBackend(loomThreadFactory())
      val taskRunner = TaskRunner(backend)

      OkHttpClient
        .Builder()
        .connectionPool(
          buildConnectionPool(
            connectionListener = connectionListener,
            taskRunner = taskRunner,
          ),
        ).dispatcher(Dispatcher(backend.executor))
        .taskRunnerInternal(taskRunner)

  /**
   * Results are posted here as they occur. The find job is done when either one plan completes
   * successfully or all plans fail.
   */
  private val connectResults = taskRunner.backend.decorate(LinkedBlockingDeque<ConnectResult>())

  override fun find(): RealConnection {
    var firstException: IOException? = null
    try {
      while (tcpConnectsInFlight.isNotEmpty() || routePlanner.hasNext()) {

And to communicate using WebSockets with your backend you would probably use your frontend's utilities.

Or you might have a native mobile application that communicates with your WebSocket backend directly, in native code.

Or you might have any other way to communicate with the WebSocket endpoint.

---

- **Data Persistence**: Multiple backend options including OpenSearch integration

## Technology Stack

- **Java**: 21+ (requires Java 21 or higher)
- **Build System**: Maven 3.x
- **DI Container**: LastaFlute DI
- **HTTP Client**: Apache HttpComponents
- **Content Extraction**: Apache Tika, Apache POI, PDFBox
- **Testing**: JUnit 4, UTFlute, Testcontainers
- **Storage Backends**: OpenSearch, Memory-based

## Quick Start