# WebSockets

When defining WebSockets, you normally declare a parameter of type `WebSocket` and with it you can read data from the client and send data to it.

It is provided directly by Starlette, but you can import it from `fastapi`:

```python
from fastapi import WebSocket
```

/// tip

## Proxy Configuration

Istiod's primary role - and most code - is to dynamically configure proxies (Envoy sidecars and ingress, gRPC, ztunnel, and more). This roughly consists of 3 parts:
1. Config ingestion (inputs to the system)
1. Config translation
1. Config serving (XDS)

### Config Ingestion

- [ ] Provide integration tests (under `<subproject>/src/integTest`) to verify changes from a user perspective.
- [ ] Provide unit tests (under `<subproject>/src/test`) to verify logic.
- [ ] Update User Guide, DSL Reference, and Javadoc for public-facing changes.

-->

<!--
 | This is the toolchains file for Maven. It can be specified at two levels:
 |
 |  1. User Level. This toolchains.xml file provides configuration for a single user,
 |                 and is normally provided in ${user.home}/.m2/toolchains.xml.
 |
 |                 NOTE: This location can be overridden with the CLI option:
 |
 |                 -t /path/to/user/toolchains.xml
 |
 |  2. Installation Level.

// byte arrays sized based on width.
func NewBytePoolCap(maxSize uint64, width int, capwidth int) (bp *BytePoolCap) {
	if capwidth <= 0 {
		panic("total buffer capacity must be provided")
	}
	if capwidth < 64 {
		panic("buffer capped with smaller than 64 bytes is not supported")
	}
	if width > capwidth {
		panic("minimum buffer length cannot be > capacity of the buffer")
	}
	return &BytePoolCap{

Eclipse Public License - v 2.0

    THE ACCOMPANYING PROGRAM IS PROVIDED UNDER THE TERMS OF THIS ECLIPSE
    PUBLIC LICENSE ("AGREEMENT"). ANY USE, REPRODUCTION OR DISTRIBUTION
    OF THE PROGRAM CONSTITUTES RECIPIENT'S ACCEPTANCE OF THIS AGREEMENT.

1. DEFINITIONS

"Contribution" means:

  a) in the case of the initial Contributor, the initial content
     Distributed under this Agreement, and

  b) in the case of each subsequent Contributor:

          latch2.countDown()
        }
      }
    val request2Listener: EventListener =
      object : EventListener() {
        override fun connectStart(
          call: Call,
          inetSocketAddress: InetSocketAddress,
          proxy: Proxy,
        ) {
          // Let request1 proceed to make a connection.
          latch1.countDown()

    Subscriber subscriber = Subscriber.create(bus, this, method);

    subscriber.invokeSubscriberMethod(FIXTURE_ARGUMENT);

    assertTrue("Subscriber must call provided method", methodCalled);
    assertTrue(
        "Subscriber argument must be exactly the provided object.",
        methodArgument == FIXTURE_ARGUMENT);
  }

  public void testInvokeSubscriberMethod_exceptionWrapping() throws Throwable {

	mac := hmac.New(sha256.New, extKey)
	mac.Write([]byte(Context))
	mac.Write(nonce[:])
	mac.Sum(key[:0])
	return key
}

// GenerateIV generates a new random 256 bit IV from the provided source
// of randomness. If random is nil the default PRNG of the system
// (crypto/rand) is used.
func GenerateIV(random io.Reader) (iv [32]byte) {
	if random == nil {
		random = rand.Reader
	}

        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def get_query_token(token: str):
    if token != "jessica":