app = FastAPI()


@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket, session: SessionDep):
    await websocket.accept()
    for item in session:
        await websocket.send_text(f"{item}")


@app.websocket("/ws-broken")
async def websocket_endpoint_broken(websocket: WebSocket, session: BrokenSessionDep):
    await websocket.accept()
    for item in session:

]

app = FastAPI()


@app.websocket("/function-scope")
async def function_scope(websocket: WebSocket, session: SessionFuncDep) -> Any:
    await websocket.accept()
    await websocket.send_json({"is_open": session.open})


@app.websocket("/request-scope")
async def request_scope(websocket: WebSocket, session: SessionRequestDep) -> Any:
    await websocket.accept()
    await websocket.send_json({"is_open": session.open})

          text: String,
        ) {
          webSocket.send(text)
        }

        override fun onClosing(
          webSocket: WebSocket,
          code: Int,
          reason: String,
        ) {
          webSocket.close(1000, null)
          latch.countDown()
        }

        override fun onFailure(
          webSocket: WebSocket,
          t: Throwable,
          response: Response?,

# 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.

Read more about it in the [FastAPI docs for WebSockets](https://fastapi.tiangolo.com/advanced/websockets/)

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

```python
from fastapi import WebSocket
```

/// tip

  @Override public void onMessage(WebSocket webSocket, String text) {
    System.out.println("onMessage: " + text);
  }

  @Override public void onClosing(WebSocket webSocket, int code, String reason) {
    webSocket.close(1000, null);
    System.out.println("onClose (" + code + "): " + reason);
  }

  @Override public void onFailure(WebSocket webSocket, Throwable t, Response response) {

    client.dispatcher().executorService().shutdown();
  }

  @Override public void onOpen(WebSocket webSocket, Response response) {
    webSocket.send("Hello...");
    webSocket.send("...World!");
    webSocket.send(ByteString.decodeHex("deadbeef"));
    webSocket.close(1000, "Goodbye, World!");
  }

  @Override public void onMessage(WebSocket webSocket, String text) {
    System.out.println("MESSAGE: " + text);
  }

   * messages.
   */
  open fun onOpen(
    webSocket: WebSocket,
    response: Response,
  ) {
  }

  /** Invoked when a text (type `0x1`) message has been received. */
  open fun onMessage(
    webSocket: WebSocket,
    text: String,
  ) {
  }

  /** Invoked when a binary (type `0x2`) message has been received. */
  open fun onMessage(
    webSocket: WebSocket,
    bytes: ByteString,
  ) {
  }

  /**

 * Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits=15
 * Sec-WebSocket-Extensions: permessage-deflate; client_no_context_takeover
 * Sec-WebSocket-Extensions: permessage-deflate; server_max_window_bits="15"
 * Sec-WebSocket-Extensions: permessage-deflate; server_max_window_bits=15
 * Sec-WebSocket-Extensions: permessage-deflate; server_no_context_takeover
 * Sec-WebSocket-Extensions: permessage-deflate; server_no_context_takeover;

):
    await websocket.accept()
    await websocket.send_json(value)
    await websocket.close()


client = TestClient(app)


def test_value_extracting_by_http():
    response = client.get("/http")
    assert response.status_code == 200
    assert response.json() == 42


def test_value_extracting_by_ws():
    with client.websocket_connect("/ws") as websocket:

async def get_cookie_or_token(
    websocket: WebSocket,
    session: str | None = Cookie(default=None),
    token: str | None = Query(default=None),
):
    if session is None and token is None:
        raise WebSocketException(code=status.WS_1008_POLICY_VIOLATION)
    return session or token


@app.websocket("/items/{item_id}/ws")
async def websocket_endpoint(
    websocket: WebSocket,
    item_id: str,