To create the callback *path operation* use the same `APIRouter` you created above.

It should look just like a normal FastAPI *path operation*:

* It should probably have a declaration of the body it should receive, e.g. `body: InvoiceEvent`.
* And it could also have a declaration of the response it should return, e.g. `response_model=InvoiceEventReceived`.

```Python hl_lines="16-18  21-22  28-32"

    That's because it is using the same name as in the OpenAPI spec. So that if you need to investigate more about any of these security schemes you can just copy and paste it to find more information about it.

The `oauth2_scheme` variable is an instance of `OAuth2PasswordBearer`, but it is also a "callable".

It could be called as:

```Python
oauth2_scheme(some, parameters)
```

The result of calling it is something that can be encoded with the Python standard <a href="https://docs.python.org/3/library/json.html#json.dumps" class="external-link" target="_blank">`json.dumps()`</a>.

It doesn't return a large `str` containing the data in JSON format (as a string). It returns a Python standard data structure (e.g. a `dict`) with values and sub-values that are all compatible with JSON.

!!! note

    override fun execute(context: ComponentMetadataContext) {
        context.details.allVariants {
            withDependencies {
                filter { it.group == "xml-apis" }.forEach {
                    it.version { require("1.4.01") }
                    it.because("Gradle has trouble with the versioning scheme and pom redirects in higher versions")
                }
            }
        }
    }
}

                "maven-it-plugin",
                "0.1",
                "compile",
                "jar",
                null,
                new DefaultArtifactHandler("ignore"));
        PluginDescriptor descriptor = new PluginDescriptor();
        descriptor.setGroupId("org.apache.maven.its.plugins");
        descriptor.setArtifactId("maven-it-plugin");
        descriptor.setVersion("0.1");

  private Iterator<? extends ByteSource> it;
  @CheckForNull private InputStream in;

  /**
   * Creates a new instance.
   *
   * @param it an iterator of I/O suppliers that will provide each substream
   */
  public MultiInputStream(Iterator<? extends ByteSource> it) throws IOException {
    this.it = checkNotNull(it);
    advance();
  }

  @Override

The `lifespan` parameter of the `FastAPI` app takes an **async context manager**, so we can pass our new `lifespan` async context manager to it.

```Python hl_lines="22"
{!../../../docs_src/events/tutorial003.py!}
```

## Alternative Events (deprecated)

!!! warning

By default it will listen on the IP address `127.0.0.1`, which is the IP for your machine to communicate with itself alone (`localhost`).

## `fastapi run`

When you run `fastapi run`, it will run on production mode by default.

It will have **auto-reload disabled** by default.

TensorFlow server (`tf.train.Server`). The TensorFlow server is intended for
internal communication only. It is not built for use in untrusted environments
or networks.

For performance reasons, the default TensorFlow server does not include any
authorization protocol and sends messages unencrypted. It accepts connections
from anywhere, and executes the graphs it is sent without performing any checks.

      render: java
    validations:
      required: true

  - type: textarea
    attributes:
      label: How do you want it to be improved?
    validations:
      required: true

  - type: textarea
    attributes:
      label: Why do we need it to be improved?
    validations:
      required: true

  - type: textarea
    attributes:
      label: Example
      description: >