buffer.putInt(fileNameBytes.length);
        buffer.put(fileNameBytes);

        // Return only the used portion of the buffer
        byte[] result = new byte[buffer.position()];
        buffer.rewind();
        buffer.get(result);
        return result;
    }

    /**
     * Helper method to create a buffer with multiple notifications
     */

			// Put the '\r' back on buf and drop it from line.
			// Let the next call to ReadLine check for "\r\n".
			if b.r == 0 {
				// should be unreachable
				panic("bufio: tried to rewind past start of buffer")
			}
			b.r--
			line = line[:len(line)-1]
		}
		return line, true, nil
	}

	if len(line) == 0 {
		if err != nil {
			line = nil
		}
		return
	}

# Behind a Proxy { #behind-a-proxy }

In many situations, you would use a **proxy** like Traefik or Nginx in front of your FastAPI app.

These proxies could handle HTTPS certificates and other things.

## Proxy Forwarded Headers { #proxy-forwarded-headers }

        // Test registration
        String regId = mockService.registerWitness("\\\\server\\share", "192.168.1.100", 1);
        assertNotNull(regId);
        assertEquals(1, mockService.getRegistrationCount());
        assertTrue(mockService.hasRegistration(regId));

        // Test unregistration
        assertTrue(mockService.unregisterWitness(regId));
        assertEquals(0, mockService.getRegistrationCount());

# Including WSGI - Flask, Django, others { #including-wsgi-flask-django-others }

You can mount WSGI applications as you saw with [Sub Applications - Mounts](sub-applications.md){.internal-link target=_blank}, [Behind a Proxy](behind-a-proxy.md){.internal-link target=_blank}.

For that, you can use the `WSGIMiddleware` and use it to wrap your WSGI application, for example, Flask, Django, etc.

## Using `WSGIMiddleware` { #using-wsgimiddleware }

have its own mounted sub-applications and everything would work correctly, because FastAPI handles all these `root_path`s automatically.

You will learn more about the `root_path` and how to use it explicitly in the section about [Behind a Proxy](behind-a-proxy.md){.internal-link target=_blank}....

This would be useful for example to properly handle redirects.

/// tip

You can learn more about this in the documentation for [Behind a Proxy - Enable Proxy Forwarded Headers](../advanced/behind-a-proxy.md#enable-proxy-forwarded-headers){.internal-link target=_blank}

///

## Recap { #recap }

If you integrate your API with an OAuth2 provider, you will be able to authenticate and come back to the API docs with the acquired credentials. And interact with it using the real OAuth2 authentication.

Swagger UI will handle it behind the scenes for you, but it needs this "redirect" helper.

///

### Create a *path operation* to test it { #create-a-path-operation-to-test-it }

Now, to be able to test that everything works, create a *path operation*:

Using a relative URL is important to make sure your application keeps working even in an advanced use case like [Behind a Proxy](../../advanced/behind-a-proxy.md){.internal-link target=_blank}.

///

By default, **FastAPI** would automatically convert that return value to JSON using the `jsonable_encoder` explained in [JSON Compatible Encoder](../tutorial/encoder.md){.internal-link target=_blank}.

Then, behind the scenes, it would put that JSON-compatible data (e.g. a `dict`) inside of a `JSONResponse` that would be used to send the response to the client.

But you can return a `JSONResponse` directly from your *path operations*.