# WebSockets { #websockets }

You can use <a href="https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API" class="external-link" target="_blank">WebSockets</a> with **FastAPI**.

## Install `websockets` { #install-websockets }

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and install `websockets` (a Python library that makes it easy to use the "WebSocket" protocol):

<div class="termy">

            return getMailingListKey(mailingList);
        }
    }

    /**
     * KeyComputer for Developer
     */
    private class DeveloperKeyComputer implements KeyComputer<Developer> {
        @Override
        public Object key(Developer developer) {
            return getDeveloperKey(developer);
        }
    }

    /**
     * KeyComputer for Contributor
     */

  public static final MediaType WASM_APPLICATION = createConstant(APPLICATION_TYPE, "wasm");

  /**
   * NaCl applications. For more information see <a
   * href="https://developer.chrome.com/native-client/devguide/coding/application-structure">the
   * Developer Guide for Native Client Application Structure</a>.
   *
   * @since 20.0
   */
  public static final MediaType NACL_APPLICATION = createConstant(APPLICATION_TYPE, "x-nacl");

/// note | Technical Details

You could also use `from starlette import status`.

**FastAPI** provides the same `starlette.status` as `fastapi.status` just as a convenience for you, the developer. But it comes directly from Starlette.

///

## Tags { #tags }

You can add tags to your *path operation*, pass the parameter `tags` with a `list` of `str` (commonly just one `str`):

            context.terminal.writer().println("This tool works only in interactive mode!");
            context.terminal
                    .writer()
                    .println("Tool purpose is to configure password management on developer workstations.");
            context.terminal
                    .writer()
                    .println(

Если вы хотите узнать больше об этих кодировках и полях форм, перейдите по ссылке <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/POST" class="external-link" target="_blank"><abbr title="Mozilla Developer Network – Сеть разработчиков Mozilla">MDN</abbr> web docs for <code>POST</code></a>.

///

/// warning | Внимание

# CORS（跨域资源共享）

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">CORS 或者「跨域资源共享」</a> 指浏览器中运行的前端拥有与后端通信的 JavaScript 代码，而后端处于与前端不同的「源」的情况。

## 源

源是协议（`http`，`https`）、域（`myapp.com`，`localhost`，`localhost.tiangolo.com`）以及端口（`80`、`443`、`8080`）的组合。

因此，这些都是不同的源：

* `http://localhost`
* `https://localhost`
* `http://localhost:8080`

即使它们都在 `localhost` 中，但是它们使用不同的协议或者端口，所以它们都是不同的「源」。

## 步骤

Щоб дізнатися більше про ці типи кодування та формові поля, ознайомтеся з <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/POST" class="external-link" target="_blank"><abbr title="Mozilla Developer Network">документацією MDN</abbr> щодо <code>POST</code></a>.

///

/// warning | Увага

Заголовки прокси:

* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-For" class="external-link" target="_blank">X-Forwarded-For</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Proto" class="external-link" target="_blank">X-Forwarded-Proto</a>

devices, including multicore CPUs, general purpose GPUs, and custom-designed ASICs known as Tensor Processing Units (TPUs). This architecture gives flexibility to the application developer, whereas in previous “parameter server” designs the management of shared state is built into the system, TensorFlow enables developers to experiment with novel optimizations and training algorithms. TensorFlow supports a variety of applications, with a focus on training and inference on deep neural networks. Several...