* successfully cancelled step will immediately start closing all objects captured for later closing
 * by it and by its input steps.
 *
 * <h3>Ending a pipeline</h3>
 *
 * Each {@code ClosingFuture} pipeline must be ended. To end a pipeline, decide whether you want to
 * close the captured objects automatically or manually.
 *
 * <h4>Automatically closing</h4>
 *

If there are compelling use cases for early closing in dependencies with `yield`, I would consider adding a new way to opt in to early closing.

### Dependencies with `yield` and `except`, Technical Details { #dependencies-with-yield-and-except-technical-details }

 *
 *  * **Open:** the web socket has been accepted by the remote peer and is fully operational.
 *    Messages in either direction are enqueued for immediate transmission.
 *
 *  * **Closing:** one of the peers on the web socket has initiated a graceful shutdown. The web
 *    socket will continue to transmit already-enqueued messages but will refuse to enqueue new
 *    ones.
 *

            saveInfo(messages -> messages.addSuccessStartedDataUpdate(GLOBAL));
        }
        return redirect(getClass());
    }

    /**
     * Reloads the document index by closing and reopening it.
     *
     * @param form the action form (validated but not used for configuration)
     * @return HTML response redirecting to the maintenance page
     */
    @Execute
    @Secured({ ROLE })

## Technical Details { #technical-details }

FastAPI implements some SSE best practices out of the box.

* Send a **"keep alive" `ping` comment** every 15 seconds when there hasn't been any message, to prevent some proxies from closing the connection, as suggested in the [HTML specification: Server-Sent Events](https://html.spec.whatwg.org/multipage/server-sent-events.html#authoring-notes).
* Set the `Cache-Control: no-cache` header to **prevent caching** of the stream.

{* ../../docs_src/websockets_/tutorial002_an_py310.py hl[68:69,82] *}

/// info

As this is a WebSocket it doesn't really make sense to raise an `HTTPException`, instead we raise a `WebSocketException`.

You can use a closing code from the [valid codes defined in the specification](https://tools.ietf.org/html/rfc6455#section-7.4.1).

///

### Try the WebSockets with dependencies { #try-the-websockets-with-dependencies }

/**
 * A simple {@link Supplier} of {@link SessionBuilder} instances, that on each call supplies newly
 * constructed instance. To create session out of builder, use {@link SessionBuilder#build()}. For proper closing
 * of sessions, use {@link CloseableSession#close()} method on built instance(s).
 * <p>
 * Extend this class and override methods to customize, if needed.
 *
 * @since 4.0.0

    // TODO(cgdecker): Add CharSource.slice?
    StringBuilder builder = new StringBuilder();
    Reader reader = concatenated.openStream(); // no need to worry about closing
    for (int i = 0; i < 8; i++) {
      builder.append((char) reader.read());
    }
    assertThat(builder.toString()).isEqualTo(expected);
  }

Think of it this way: we can already write LLM prompts or run automated tools ourselves, and that would be faster than reviewing external PRs.

### Closing Automated and AI PRs

If we see PRs that seem AI generated or automated in similar ways, we'll flag them and close them.

The same applies to comments and descriptions, please don't copy paste the content generated by an LLM.

# Dependencies with yield { #dependencies-with-yield }

FastAPI supports dependencies that do some <dfn title='sometimes also called "exit code", "cleanup code", "teardown code", "closing code", "context manager exit code", etc.'>extra steps after finishing</dfn>.

To do this, use `yield` instead of `return`, and write the extra steps (code) after.

/// tip

Make sure to use `yield` one single time per dependency.

///

/// note | Technical Details