These are the exceptions that you can raise to show errors to the client.

When you raise an exception, as would happen with normal Python, the rest of the execution is aborted. This way you can raise these exceptions from anywhere in the code to abort a request and show the error to the client.

You can use:

* `HTTPException`
* `WebSocketException`

These exceptions can be imported directly from `fastapi`:

```python

import org.apache.maven.api.Service;
import org.apache.maven.api.annotations.Experimental;
import org.apache.maven.api.annotations.Nonnull;

/**
 * Service for creating {@link PathMatcher} objects that can be used to filter files
 * based on include/exclude patterns. This service provides a clean API for plugins
 * to create path matchers without directly depending on implementation classes.
 * <p>

Here is the reference for it and its parameters.

You can import it directly from `fastapi`:

```python
from fastapi import Depends
```

::: fastapi.Depends

## `Security()`

For many scenarios, you can handle security (authorization, authentication, etc.) with dependencies, using `Depends()`.

But when you want to also declare OAuth2 scopes, you can use `Security()` instead of `Depends()`.

<%@page pageEncoding="UTF-8" contentType="text/html; charset=UTF-8"%>
<h2>Query Syntax</h2>
<dl>
	<dt>Field</dt>
	<dd>
		You can search any field by typing the field name followed by a colon
		":" and then the term you are looking for. If you want to find
		documents which has "Fess" as the document title, you can enter:
		<pre>title:Fess</pre>
		The available fields are "url", "host", "site", "title", "content",

* Processing data:
    * For example, let's say you receive a file that must go through a slow process, you can return a response of "Accepted" (HTTP 202) and process the file in the background.

## Using `BackgroundTasks` { #using-backgroundtasks }

   * higher value than you need can waste space and time, and a significantly lower value can lead
   * to thread contention. But overestimates and underestimates within an order of magnitude do not
   * usually have much noticeable impact. A value of one permits only one thread to modify the cache
   * at a time, but since read operations and cache loading computations can proceed concurrently,

  ) {
  }

  /**
   * Invoked just prior to initiating a socket connection.
   *
   * This method will be invoked if no existing connection in the [ConnectionPool] can be reused.
   *
   * This can be invoked more than 1 time for a single [Call]. For example, if the response to the
   * [Call.request] is a redirect to a different address, or a connection is retried.
   */
  open fun connectStart(

For those cases, you can use a `Response` parameter.

## Use a `Response` parameter { #use-a-response-parameter }

You can declare a parameter of type `Response` in your *path operation function* (as you can do for cookies and headers).

And then you can set the `status_code` in that *temporal* response object.

There are multiple tools that you can use to create those dependables, and they get integrated into OpenAPI so they are shown in the automatic docs UI, they can be used by automatically generated clients and SDKs, etc.

You can import them from `fastapi.security`:

```python
from fastapi.security import (
    APIKeyCookie,
    APIKeyHeader,

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.

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

```python
from fastapi import WebSocket
```

/// tip