# Sub Applications - Mounts { #sub-applications-mounts }

If you need to have two independent FastAPI applications, with their own independent OpenAPI and their own docs UIs, you can have a main app and "mount" one (or more) sub-application(s).

## Mounting a **FastAPI** application { #mounting-a-fastapi-application }

# 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 }

    }

    @Test
    @DisplayName("Test hasMoreElements becomes false when all data is sent")
    void testHasMoreElementsBecomeFalse() {
        // Set small amounts so everything fits in one message
        transaction.setParameterBytesWritten(10);
        transaction.setDataBytesWritten(10);

        // First call processes all data
        transaction.nextElement();

/// tip

All this might not seem as useful with these simple examples.

But you will see how useful it is in the chapters about **security**.

And you will also see the amounts of code it will save you.

///

## Sub Applications { #sub-applications }

and then it won't include it in the OpenAPI schema.

## Mounting a sub-application { #mounting-a-sub-application }

If you need to mount a sub-application (as described in [Sub Applications - Mounts](sub-applications.md){.internal-link target=_blank}) while also using a proxy with `root_path`, you can do it normally, as you would expect.

        // When - initially should not need rotation
        assertFalse(context.needsKeyRotation(), "Should not need rotation initially");

        // Note: We can't directly test the byte limit without encrypting large amounts of data,
        // but we can verify the method exists and returns proper boolean
    }

    @Test
    @DisplayName("Should reset key rotation tracking")
    void testResetKeyRotationTracking() {

// compacted until the limit is reached.
//
// This ensures that any branch will never contain an unreasonable amount of other branches,
// and also that small branches with few objects don't take up unreasonable amounts of space.
// This keeps the cache size at a reasonable size for all buckets.
//
// Whenever a branch is scanned, it is assumed that it will be un-compacted
// before it hits any of the above limits.

		// https://en.wikipedia.org/wiki/Copy_protection so the incoming stream
		// is always going to be in-memory as we cannot re-read from what we
		// wrote to disk - since that amounts to "copying" from a "copy"
		// instead of "copying" from source, we need the stream to be seekable
		// to ensure that we can make fan-out calls concurrently.
		buf := bytebufferpool.Get()
		defer func() {

### Bug or Regression