When you need to declare dependencies with OAuth2 scopes you use `Security()`.

But you still need to define what is the dependable, the callable that you pass as a parameter to `Depends()` or `Security()`.

There are multiple tools that you can use to create those dependables, and they get integrated into OpenAPI so they are shown in the automatic docs UI, they can be used by automatically generated clients and SDKs, etc.

## Overview

**Fess Crawler** is a powerful, flexible Java-based web crawling framework designed for enterprise-scale content extraction and processing. Built with a modular architecture, it supports multiple protocols (HTTP/HTTPS, File System, FTP, SMB, Cloud Storage) and provides extensive content extraction capabilities from various document formats.

### Key Features

///

With that you can connect the WebSocket and then send and receive messages:

<img src="/img/tutorial/websockets/image05.png">

## Handling disconnections and multiple clients { #handling-disconnections-and-multiple-clients }

When a WebSocket connection is closed, the `await websocket.receive_text()` will raise a `WebSocketDisconnect` exception, which you can then catch and handle like in this example.

import java.lang.annotation.Target;

/**
 * Marks an event subscriber method as being thread-safe. This annotation indicates that EventBus
 * may invoke the event subscriber simultaneously from multiple threads.
 *
 * <p>This does not mark the method, and so should be used in combination with {@link Subscribe}.
 *
 * @author Cliff Biffle
 * @since 10.0
 */
@Retention(RetentionPolicy.RUNTIME)

        int expectedFlags = DcerpcConstants.DCERPC_FIRST_FRAG | DcerpcConstants.DCERPC_LAST_FRAG;
        assertEquals(expectedFlags, dfsRootEnum.getFlags());
    }

    @Test
    @DisplayName("Multiple server names should be handled correctly")
    void testDifferentServerNames() {
        // Test with different server names
        String[] serverNames = { "server1", "domain.local", "192.168.1.100", "FILESERVER" };

   *
   * [rfc_7230]: https://tools.ietf.org/html/rfc7230
   */
  HTTP_1_1("http/1.1"),

  /**
   * Chromium's binary-framed protocol that includes header compression, multiplexing multiple
   * requests on the same socket, and server-push. HTTP/1.1 semantics are layered on SPDY/3.
   *
   * Current versions of OkHttp do not support this protocol.
   */

    public void test_multiple_quick_operations() {
        try {
            // Multiple quick operations to verify overall performance
            dataIndexHelper.setCrawlingExecutionInterval(1L);
            for (int i = 0; i < 3; i++) {
                dataIndexHelper.crawl("test-session-" + i);
            }
            assertTrue("Multiple operations should complete quickly", true);
        } catch (Exception e) {

        } finally {
            // Clean up system property
            System.clearProperty(testKey);
        }
    }

    // Test multiple gets with different keys
    public void test_get_multipleKeys() {
        // Test getting multiple different properties
        String value1 = fessConfig.get("domain.title");
        String value2 = fessConfig.get("search_engine.type");

        // Verify close was called
        verify(autoCloseableHandle, times(1)).close();
    }

    /**
     * Test multiple watch calls returning different results
     */
    @Test
    void testMultipleWatchCalls() throws CIFSException {
        // Setup mock behavior for multiple calls
        List<FileNotifyInformation> firstBatch = Arrays.asList(fileNotifyInfo1);

If you don't know, you will learn what a "password hash" is in the [security chapters](security/simple-oauth2.md#password-hashing){.internal-link target=_blank}.

///

## Multiple models { #multiple-models }

Here's a general idea of how the models could look like with their password fields and the places where they are used:

{* ../../docs_src/extra_models/tutorial001_py310.py hl[7,9,14,20,22,27:28,31:33,38:39] *}