执行顺序大致如下时序图所示。时间轴从上到下，每一列都代表交互或者代码执行的一部分。

```mermaid
sequenceDiagram

participant client as Client
participant handler as Exception handler
participant dep as Dep with yield
participant operation as Path Operation
participant tasks as Background tasks

    Note over client,operation: Can raise exceptions, including HTTPException
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise Exception

path_prefix      (path)      namespace prefix to isolate tenants e.g. "customer1/"
coredns_path     (path)      shared bucket DNS records, default is "/skydns"
client_cert      (path)      client cert for mTLS authentication
client_cert_key  (path)      client cert key for mTLS authentication
comment          (sentence)  optionally add a comment to this setting
```

or environment variables

```
KEY:

			enabled = true
			if p.ClientID == "" && p.ClientSecret == "" && configURL == "" {
				enabled = false
			}
		}

		// No need to continue loading if the config is not enabled.
		if !enabled {
			continue
		}

		// Validate that client ID has not been duplicately specified.
		if seenClientIDs.Contains(p.ClientID) {

Here's a visual representation of how the **proxy** adds forwarded headers between the client and the **application server**:

```mermaid
sequenceDiagram
    participant Client
    participant Proxy as Proxy/Load Balancer
    participant Server as FastAPI Server

    Client->>Proxy: HTTPS Request<br/>Host: mysuperapp.com<br/>Path: /items

    Note over Proxy: Proxy adds forwarded headers

          "normalization-java"
        ],
        "parallelizationMethod": {
          "name": "TestDistribution"
        }
      },
      {
        "subprojects": [
          "build-cache-example-client",
          "client-services",
          "composite-builds",
          "docs",
          "files",
          "model-reflect",
          "request-handler-worker",
          "security",
          "service-registry-impl",

		},
		IsPresent: true,
	},
	{ // 4
		Env: map[string]string{
			EnvKESEndpoint:   "https://127.0.0.1:7373",
			EnvKESDefaultKey: "minio-key",
			EnvKESClientKey:  "/tmp/client.key",
			EnvKESClientCert: "/tmp/client.crt",
		},
		IsPresent: true,
	},
	{ // 5
		Env: map[string]string{
			EnvKMSEndpoint: "https://127.0.0.1:7373",
			EnvKESEndpoint: "https://127.0.0.1:7373",
		},
		ShouldFail: true,

*--------------------+---------------+------------+------------+-----------+---------------------+-----------------------+
| <<<ejb-client>>>   | <<<client>>>  | <<<jar>>>  | <<<ejb>>>  | java      | <<<true>>>          |                       |
*--------------------+---------------+------------+------------+-----------+---------------------+-----------------------+

    * A special case is `204`, "No Content".  This response is used when there is no content to return to the client, and so the response must not have a body.
* **`300 - 399`** are for "Redirection".  Responses with these status codes may or may not have a body, except for `304`, "Not Modified", which must not have one.
* **`400 - 499`** are for "Client error" responses. These are the second type you would probably use the most.

Quand vous avez besoin d'envoyer de la donnée depuis un client (comme un navigateur) vers votre API, vous l'envoyez en tant que **corps de requête**.

Le corps d'une **requête** est de la donnée envoyée par le client à votre API. Le corps d'une **réponse** est la donnée envoyée par votre API au client.

Votre API aura presque toujours à envoyer un corps de **réponse**. Mais un client n'a pas toujours à envoyer un corps de **requête**.

///

Wenn wir eine Instanz der Klasse `OAuth2PasswordBearer` erstellen, übergeben wir den Parameter `tokenUrl`. Dieser Parameter enthält die URL, die der Client (das Frontend, das im Browser des Benutzers ausgeführt wird) verwendet, wenn er den `username` und das `password` sendet, um einen Token zu erhalten.

{* ../../docs_src/security/tutorial001_an_py39.py hl[8] *}

/// tip | Tipp