Ainsi, elle enverra le premier élément, le client le recevra et commencera à le traiter, et vous pourriez être encore en train de produire l'élément suivant.

```mermaid
sequenceDiagram
    participant App
    participant Client

    App->>App: Produce Item 1
    App->>Client: Send Item 1
    App->>App: Produce Item 2
    Client->>Client: Process Item 1

La séquence d'exécution ressemble plus ou moins à ce diagramme. Le temps s'écoule de haut en bas. Et chaque colonne représente une des parties qui interagit ou exécute du code.

```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

여러분은 다음 장에서 함수를 제외하고서, "다른 것들"이 어떻게 의존성으로 사용되는지 알게 될 것입니다.

///

새로운 요청이 도착할 때마다, **FastAPI**는 다음을 처리합니다:

* 올바른 매개변수를 가진 의존성("디펜더블") 함수를 호출합니다.
* 함수에서 결과를 받아옵니다.
* *경로 처리 함수*에 있는 매개변수에 그 결과를 할당합니다

```mermaid
graph TB

common_parameters(["common_parameters"])
read_items["/items/"]
read_users["/users/"]

common_parameters --> read_items
common_parameters --> read_users
```

Voici une représentation visuelle de la façon dont le **proxy** ajoute des en‑têtes transférés entre le client et le **serveur d'application** :

```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

### Como funcionam os headers encaminhados pelo proxy { #how-proxy-forwarded-headers-work }

Aqui está uma representação visual de como o **proxy** adiciona headers encaminhados entre o cliente e o **servidor da aplicação**:

```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

Assim, ela envia o primeiro item, o cliente o recebe e começa a processá-lo, enquanto você ainda pode estar produzindo o próximo item.

```mermaid
sequenceDiagram
    participant App
    participant Client

    App->>App: Produce Item 1
    App->>Client: Send Item 1
    App->>App: Produce Item 2
    Client->>Client: Process Item 1

Sie sendet also das erste Element, der Client empfängt es und beginnt mit der Verarbeitung, und Sie erzeugen währenddessen möglicherweise bereits das nächste Element.

```mermaid
sequenceDiagram
    participant App
    participant Client

    App->>App: Produce Item 1
    App->>Client: Send Item 1
    App->>App: Produce Item 2
    Client->>Client: Process Item 1

/// info | 정보

*경로 처리 함수*에서는 `query_or_cookie_extractor`라는 의존성 하나만 선언하고 있다는 점에 주목하세요.

하지만 **FastAPI**는 `query_or_cookie_extractor`를 호출하는 동안 그 결과를 전달하기 위해, 먼저 `query_extractor`를 해결해야 한다는 것을 알고 있습니다.

///

```mermaid
graph TB

query_extractor(["query_extractor"])
query_or_cookie_extractor(["query_or_cookie_extractor"])

read_query["/items/"]

query_extractor --> query_or_cookie_extractor --> read_query
```

/// info

注意，在路徑操作函式中我們只宣告了一個相依項 `query_or_cookie_extractor`。

但 **FastAPI** 會知道它必須先解析 `query_extractor`，在呼叫 `query_or_cookie_extractor` 時把其結果傳入。

///

```mermaid
graph TB

query_extractor(["query_extractor"])
query_or_cookie_extractor(["query_or_cookie_extractor"])

read_query["/items/"]

query_extractor --> query_or_cookie_extractor --> read_query
```

Последовательность выполнения примерно такая, как на этой схеме. Время течёт сверху вниз. А каждый столбец — это одна из частей, взаимодействующих с кодом или выполняющих код.

```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