---> 100%
```

</div>

## WebSockets client

### In production

In your production system, you probably have a frontend created with a modern framework like React, Vue.js or Angular.

And to communicate using WebSockets with your backend you would probably use your frontend's utilities.

Or you might have a native mobile application that communicates with your WebSocket backend directly, in native code.

      Map<? extends Class<? extends S>, ? extends S> map) {
    if (map instanceof ImmutableClassToInstanceMap) {
      @SuppressWarnings("rawtypes") // JDT-based J2KT Java frontend does not permit the direct cast
      Map rawMap = map;
      @SuppressWarnings("unchecked") // covariant casts safe (unmodifiable)
      ImmutableClassToInstanceMap<B> cast = (ImmutableClassToInstanceMap<B>) rawMap;

```

</div>

## WebSockets-Client

### In Produktion

In Ihrem Produktionssystem haben Sie wahrscheinlich ein Frontend, das mit einem modernen Framework wie React, Vue.js oder Angular erstellt wurde.

Und um über WebSockets mit Ihrem Backend zu kommunizieren, würden Sie wahrscheinlich die Werkzeuge Ihres Frontends verwenden.

      Map<? extends Class<? extends S>, ? extends S> map) {
    if (map instanceof ImmutableClassToInstanceMap) {
      @SuppressWarnings("rawtypes") // JDT-based J2KT Java frontend does not permit the direct cast
      Map rawMap = map;
      @SuppressWarnings("unchecked") // covariant casts safe (unmodifiable)
      ImmutableClassToInstanceMap<B> cast = (ImmutableClassToInstanceMap<B>) rawMap;

/compiler/frontend/ "Kotlin Compiler Core" Simon.Ogorodnik
/compiler/frontend.common/ "Kotlin Compiler Core" Simon.Ogorodnik
/compiler/frontend.common.jvm/ "Kotlin Compiler Core" Simon.Ogorodnik
/compiler/frontend.common-psi/ "Kotlin Compiler Core" Simon.Ogorodnik
/compiler/frontend.java/ "Kotlin Compiler Core" Simon.Ogorodnik

* **MongoDB**
* **Cassandra**
* **CouchDB**
* **ArangoDB**
* **ElasticSearch**, etc.

!!! tip
    There is an official project generator with **FastAPI** and **Couchbase**, all based on **Docker**, including a frontend and more tools: <a href="https://github.com/tiangolo/full-stack-fastapi-couchbase" class="external-link" target="_blank">https://github.com/tiangolo/full-stack-fastapi-couchbase</a>

## Import Couchbase components

// RUnlock - block until read lock is released.
func (di *distLockInstance) RUnlock(lc LockContext) {
	if lc.cancel != nil {
		lc.cancel()
	}
	di.rwMutex.RUnlock(lc.ctx)
}

// localLockInstance - frontend/top-level interface for namespace locks.
type localLockInstance struct {
	ns     *nsLockMap
	volume string
	paths  []string
	opsID  string
}

// NewNSLock - returns a lock instance for a given volume and

* Kompleks kimlik doğrulama sistemleri için destek, **database bağlantıları**, vs.
* **Taviz yok** hiçbir şeyden taviz vermeden, database frontend vs. Bütün hepsinin kolayca entegre edilebiliyor.

### Sınırsız "plug-inler"

Başka bir deyişle, plug-inlere ihtiyacımız yok, import edip direkt olarak kullanmaya başlayabiliriz.

API'nizle iletişim kuran istemciler için otomatik olarak kod oluşturmak için de kullanabilirsiniz. Örneğin, frontend, mobil veya IoT uygulamaları.

## Adım adım özet

### Adım 1: `FastAPI`yi içe aktarın

```Python hl_lines="1"
{!../../../docs_src/first_steps/tutorial001.py!}
```

# Handling Errors

There are many situations in which you need to notify an error to a client that is using your API.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.