# Dependencies { #dependencies }

**FastAPI** has a very powerful but intuitive **<dfn title="also known as components, resources, providers, services, injectables">Dependency Injection</dfn>** system.

It is designed to be very simple to use, and to make it very easy for any developer to integrate other components with **FastAPI**.

## What is "Dependency Injection" { #what-is-dependency-injection }

      this.hashFunction = new ChecksumHashFunction(this, 32, toString);
    }
  }

  /**
   * Returns a hash function implementing FarmHash's Fingerprint64, an open-source algorithm.
   *
   * <p>This is designed for generating persistent fingerprints of strings. It isn't
   * cryptographically secure, but it produces a high-quality hash with fewer collisions than some
   * alternatives we've used in the past.
   *

 *
 * <p>Listeners are registered once via {@link #addListener} and then may be invoked by {@linkplain
 * #enqueue enqueueing} and then {@linkplain #dispatch dispatching} events.
 *
 * <p>The API of this class is designed to make it easy to achieve the following properties
 *
 * <ul>
 *   <li>Multiple events for the same listener are never dispatched concurrently.
 *   <li>Events for the different listeners are dispatched concurrently.

centers. OkHttp supports modern TLS features (TLS 1.3, ALPN, certificate pinning). It can be
configured to fall back for broad connectivity.

Using OkHttp is easy. Its request/response API is designed with fluent builders and immutability. It
supports both synchronous blocking calls and async calls with callbacks.

A well behaved user agent
-------------------------

OkHttp follows modern HTTP specifications such as

    private static final String FESS_APP_DOCKER = "docker";

    /**
     * Protected constructor to prevent instantiation of this utility class.
     * This class is designed to be used statically.
     */
    protected ResourceUtil() {
        // nothing
    }

    /**
     * Gets the HTTP URL for the OpenSearch (Fesen) server.

### Translations

Help with translations is VERY MUCH appreciated! And it can't be done without the help from the community. 🌎 🚀

Translation pull requests are made by LLMs guided with prompts designed by the FastAPI team together with the community of native speakers for each supported language.

#### LLM Prompt per Language

 * create the memory pressure required to cause soft references to be cleared.
 *
 * <p>This class only provides testing utilities. It is not designed for direct use in production or
 * for benchmarking.
 *
 * @author mike nonemacher
 * @author Martin Buchholz
 * @since 11.0
 */
@GwtIncompatible
@J2ktIncompatible
@J2ObjCIncompatible // gc

This was designed this way mainly to allow using the same objects "yielded" by dependencies inside of background tasks, because the exit code would be executed after the background tasks were finished.

import org.jspecify.annotations.Nullable;

/**
 * A generalized interval on any ordering, for internal use. Supports {@code null}. Unlike {@link
 * Range}, this allows the use of an arbitrary comparator. This is designed for use in the
 * implementation of subcollections of sorted collection types.
 *
 * <p>Whenever possible, use {@code Range} instead, which is better supported.
 *
 * @author Louis Wasserman
 */
@GwtCompatible

* Dependency Injection
* HTTP Basic authentication
* HTTP Digest
* ISO format
* the JSON Schema standard
* the JSON schema
* the schema definition
* Password Flow
* Mobile

* deprecated
* designed
* invalid
* on the fly
* standard
* default
* case-sensitive
* case-insensitive

* to serve the application
* to serve the page

* the app
* the application

* the request