# WebSockets

When defining WebSockets, you normally declare a parameter of type `WebSocket` and with it you can read data from the client and send data to it.

Read more about it in the [FastAPI docs for WebSockets](https://fastapi.tiangolo.com/advanced/websockets/)

It is provided directly by Starlette, but you can import it from `fastapi`:

```python
from fastapi import WebSocket
```

/// tip

## Status

- ACCEPTED on 2024-06-21

## Context

Modern best practices when developing a Gradle plugin are to use lazy types (ConfigurableFileCollection, Provider API, domain object containers) when defining configurable parts of a plugin (tasks, extensions, domain objects).  The Provider API provides a consistent way to set conventions, wire related configuration together (extension <- domain object <- task) and avoid evaluation ordering problems.

### Validation { #validation }

* Validation for most (or all?) Python **data types**, including:
    * JSON objects (`dict`).
    * JSON array (`list`) defining item types.
    * String (`str`) fields, defining min and max lengths.
    * Numbers (`int`, `float`) with min and max values, etc.

* Validation for more exotic types, like:
    * URL.
    * Email.
    * UUID.
    * ...and others.

It will be defined in OpenAPI with `anyOf`.

To do that, use the standard Python type hint [`typing.Union`](https://docs.python.org/3/library/typing.html#typing.Union):

/// note

  ;;
esac

mkdir -p "${TARGET}"

# Download glibc's shared and development libraries based on the value of the
# `VERSION` parameter.
# Note: 'Templatizing' this and the other conditional branches would require
# defining several variables (version, os, path) making it difficult to maintain
# and extend for future modifications.
case "${VERSION}" in
devtoolset-7)
  # Download binary glibc 2.12 shared library release.

Maybe you need to start a new version, or you just got tired of running it. 🤷

///

### Lifespan function { #lifespan-function }

The first thing to notice, is that we are defining an async function with `yield`. This is very similar to Dependencies with `yield`.

{* ../../docs_src/events/tutorial003_py310.py hl[14:19] *}

## To `async` or not to `async` { #to-async-or-not-to-async }

As dependencies will also be called by **FastAPI** (the same as your *path operation functions*), the same rules apply while defining your functions.

You can use `async def` or normal `def`.

As in this case (without using `Annotated`) we have to replace the default value `None` in the function with `Query()`, we now need to set the default value with the parameter `Query(default=None)`, it serves the same purpose of defining that default value (at least for FastAPI).

So:

```Python
q: str | None = Query(default=None)
```

...makes the parameter optional, with a default value of `None`, the same as:


```Python

            } catch (IOException tolerated) {
              // it's expected that some of these will fail
            }

            Thread.yield();
          }
        });
  }

  /** Enum defining the two MoreFiles methods that delete directory contents. */
  private enum DirectoryDeleteMethod {
    DELETE_DIRECTORY_CONTENTS {
      @Override

![ReDoc](https://fastapi.tiangolo.com/img/index/index-02-redoc-simple.png)

### OpenAPI { #openapi }

**FastAPI** generates a "schema" with all your API using the **OpenAPI** standard for defining APIs.

#### "Schema" { #schema }

A "schema" is a definition or description of something. Not the code that implements it, but just an abstract description.

#### API "schema" { #api-schema }