**FastAPI** knows what to do in each case and how to reuse the same object, so that all the background tasks are merged together and are run in the background afterwards:


{* ../../docs_src/background_tasks/tutorial002_an_py310.py hl[13,15,22,25] *}

You can use the same dependency *functions* you use normally.

### Dependency requirements { #dependency-requirements }

They can declare request requirements (like headers) or other sub-dependencies:

{* ../../docs_src/dependencies/tutorial006_an_py39.py hl[8,13] *}

### Raise exceptions { #raise-exceptions }

These dependencies can `raise` exceptions, the same as normal dependencies:

Linux containers run using the same Linux kernel of the host (machine, virtual machine, cloud server, etc). This just means that they are very lightweight (compared to full virtual machines emulating an entire operating system).

    }
  }

  /**
   * Returns a hash code, having the same bit length as each of the input hash codes, that combines
   * the information of these hash codes in an ordered fashion. That is, whenever two equal hash
   * codes are produced by two calls to this method, it is <i>as likely as possible</i> that each
   * was computed from the <i>same</i> input hash codes in the <i>same</i> order.
   *

        // Should be the same instance
        assertSame(status1, status2);
        assertTrue(status1 == status2);

        // valueOf should return the same instance
        CrawlerStatus status3 = CrawlerStatus.valueOf("INITIALIZING");
        assertSame(status1, status3);
        assertTrue(status1 == status3);

        // values() array contains the same instances

    }

    @Test
    @DisplayName("Should produce consistent keys for same input")
    void testDeriveKeys_Consistency() {
        // Given
        int dialect = Smb2Constants.SMB2_DIALECT_0311;

        // When - derive same key twice
        byte[] signingKey1 = Smb3KeyDerivation.deriveSigningKey(dialect, sessionKey, preauthIntegrity);

<img src="/img/tutorial/websockets/image04.png">

And all of them will use the same WebSocket connection.

## Using `Depends` and others { #using-depends-and-others }

In WebSocket endpoints you can import from `fastapi` and use:

* `Depends`
* `Security`
* `Cookie`
* `Header`
* `Path`
* `Query`

They work the same way as for other FastAPI endpoints/*path operations*:

/* jcifs smb client library in Java
 * Copyright (C) 2002  "Michael B. Allen" <jcifs at samba dot org>
 *                   "Eric Glass" <jcifs at samba dot org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *

The parameter `summary` is available in OpenAPI 3.1.0 and above, supported by FastAPI 0.99.0 and above.

///

## Overriding the defaults { #overriding-the-defaults }

Using the information above, you can use the same utility function to generate the OpenAPI schema and override each part that you need.

/* jcifs msrpc client library in Java
 * Copyright (C) 2006  "Michael B. Allen" <jcifs at samba dot org>
 *                     "Eric Glass" <jcifs at samba dot org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *