Then, the browser will send an HTTP `OPTIONS` request to the `:80`-backend, and if the backend sends the appropriate headers authorizing the communication from this different origin (`http://localhost:8080`) then the `:8080`-browser will let the JavaScript in the frontend send its request to the `:80`-backend.

To achieve this, the `:80`-backend must have a list of "allowed origins".

```

## Example

MinIO exposes a custom S3 STS API endpoint as `Action=AssumeRoleWithCertificate`. A client has to send an HTTP `POST` request to `https://<host>:<port>?Action=AssumeRoleWithCertificate&Version=2011-06-15`. Since the authentication and authorization happens via X.509 certificates the client has to send the request over **TLS** and has to provide
a client certificate.

You will also get autocompletion for the payload to send:

<img src="/img/tutorial/generate-clients/image03.png">

/// tip

Notice the autocompletion for `name` and `price`, that was defined in the FastAPI application, in the `Item` model.

///

You will have inline errors for the data that you send:

<img src="/img/tutorial/generate-clients/image04.png">

### Conditional Cache Hit
 
When cache flags require checking the cache results are still valid an early cacheConditionalHit event is
received followed by a cache hit or miss.  Critically in the cache hit scenario the server won’t send the response body.

The response will have non-null `cacheResponse` and `networkResponse`. The cacheResponse will be used as the top level
response only if the response code is HTTP/1.1 304 Not Modified.
 
 - CallStart

   *
   * HTTP/2 requires deployments of HTTP/2 that use TLS 1.2 support
   * [CipherSuite.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256], present in Java 8+ and Android 5+.
   * Servers that enforce this may send an exception message including the string
   * `INADEQUATE_SECURITY`.
   */
  HTTP_2("h2"),

  /**
   * Cleartext HTTP/2 with no "upgrade" round trip. This option requires the client to have prior

    /** Local port to bind for SMB connections */
    protected int smbLocalPort = 0;
    /** Maximum multiplex count for concurrent requests */
    protected int maxMpxCount = SmbConstants.DEFAULT_MAX_MPX_COUNT;
    /** Send buffer size for SMB socket operations */
    protected int smbSendBufferSize = SmbConstants.DEFAULT_SND_BUF_SIZE;
    /** Receive buffer size for SMB socket operations */

    """
    # assert asyncio.iscoroutinefunction(func), "WebSocket endpoints must be async"

    async def app(scope: Scope, receive: Receive, send: Send) -> None:
        session = WebSocket(scope, receive=receive, send=send)

        async def app(scope: Scope, receive: Receive, send: Send) -> None:
            async with AsyncExitStack() as request_stack:
                scope["fastapi_inner_astack"] = request_stack

Then you just do the same in your tests.

E.g.:

* To pass a *path* or *query* parameter, add it to the URL itself.
* To pass a JSON body, pass a Python object (e.g. a `dict`) to the parameter `json`.
* If you need to send *Form Data* instead of JSON, use the `data` parameter instead.
* To pass *headers*, use a `dict` in the `headers` parameter.
* For *cookies*, a `dict` in the `cookies` parameter.

			val:   0.61,
			label: labels[3],
		},
		{
			val:   0.79,
			label: labels[2],
		},
	}
	ticker := time.NewTicker(1 * time.Millisecond)
	defer ticker.Stop()
	for _, obs := range observations {
		// Send observations once every 1ms, to simulate delay between
		// observations. This is to test the channel based
		// synchronization used internally.
		<-ticker.C
		ttfbHist.With(prometheus.Labels{"api": obs.label}).Observe(obs.val)

				// The context of the lock is canceled, this can happen
				// if one lock lost quorum due to cluster instability
				// in that case, try to lock again.
				break keepLock
			case ld.lockContext <- lkctx:
				// Send the lock context to anyone asking for it
			}
		}
	}
}

func mergeContext(ctx1, ctx2 context.Context) (context.Context, context.CancelFunc) {
	ctx, cancel := context.WithCancel(context.Background())
	go func() {