<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

Öffnen Sie Ihren Browser unter <a href="http://127.0.0.1:8000" class="external-link" target="_blank">http://127.0.0.1:8000</a>.

Sie sehen eine einfache Seite wie:

<img src="/img/tutorial/websockets/image01.png">

///

## Daten-<abbr title="Auch bekannt als: Serialisierung, Parsen, Marshalling">Konversion</abbr>

Wenn Sie dieses Beispiel ausführen und Ihren Browser unter <a href="http://127.0.0.1:8000/items/3" class="external-link" target="_blank">http://127.0.0.1:8000/items/3</a> öffnen, sehen Sie als Response:

```JSON
{"item_id":3}
```

/// check

Das Frontend (das im Browser läuft) würde also versuchen, `/openapi.json` zu erreichen und wäre nicht in der Lage, das OpenAPI-Schema abzurufen.

Da wir für unsere Anwendung einen Proxy mit dem Pfadpräfix `/api/v1` haben, muss das Frontend das OpenAPI-Schema unter `/api/v1/openapi.json` abrufen.

```mermaid
graph LR

browser("Browser")
proxy["Proxy auf http://0.0.0.0:9999/api/v1/app"]

# FORMAT NOT DOCUMENTED YET (parser is urltestparser.js)

# Based on http://trac.webkit.org/browser/trunk/LayoutTests/fast/url/script-tests/segments.js
http://example\t.\norg http://example.org/foo/bar s:http h:example.org p:/
http://user:pass@foo:21/bar;par?b#c  s:http u:user pass:pass h:foo port:21 p:/bar;par q:?b f:#c
http:foo.com  s:http h:example.org p:/foo/foo.com
\t\s\s\s:foo.com\s\s\s\n  s:http h:example.org p:/foo/:foo.com

↩️ 👥 ✔️ 🗳 ⏮️ ➡ 🔡 `/api/v1` 👆 📱, 🕸 💪 ☕ 🗄 🔗 `/api/v1/openapi.json`.

```mermaid
graph LR

browser("Browser")
proxy["Proxy on http://0.0.0.0:9999/api/v1/app"]
server["Server on http://127.0.0.1:8000/app"]

browser --> proxy
proxy --> server
```

/// tip

📢 `0.0.0.0` 🛎 ⚙️ ⛓ 👈 📋 👂 🔛 🌐 📢 💪 👈 🎰/💽.

///

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Environment (please complete the following information):**
 - OS: [e.g. Windows 10]
 - Browser [e.g. chrome, safari]
 - Version [e.g. 13.5.0]

**Additional context**

.git
.github
default.etcd
*.gz
*.tar.gz
*.bzip2
*.zip
browser/node_modules
node_modules
docs/debugging/s3-verify/s3-verify
docs/debugging/xl-meta/xl-meta
docs/debugging/s3-check-md5/s3-check-md5
docs/debugging/hash-set/hash-set
docs/debugging/healing-bin/healing-bin
docs/debugging/inspect/inspect
docs/debugging/pprofgoparser/pprofgoparser

    id: what-did-you-do
    attributes:
      label: "What did you do?"
      description: "If possible, provide a recipe for reproducing the error. Starting with a Private/Incognito tab/window may help rule out problematic browser extensions."
    validations:
      required: true
  - type: textarea
    id: actual-behavior
    attributes:
      label: "What did you see happen?"
    validations:
      required: true
  - type: textarea

<div class="termy">

```console
$ fastapi dev main.py

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

Open your browser at <a href="http://127.0.0.1:8000" class="external-link" target="_blank">http://127.0.0.1:8000</a>.

You will see a simple page like:

<img src="/img/tutorial/websockets/image01.png">

```mermaid
graph LR

browser("Browser")
proxy["Proxy on http://0.0.0.0:9999/api/v1/app"]
server["Server on http://127.0.0.1:8000/app"]

browser --> proxy
proxy --> server
```

/// tip | "Dica"