## 0.50.0

* Add link to Release Notes from docs about pinning versions for deployment. PR [#1058](https://github.com/tiangolo/fastapi/pull/1058).
* Upgrade code to use the latest version of Starlette, including:
    * Several bug fixes.
    * Optional redirects of slashes, with or without ending in `/`.
    * Events for routers, `"startup"`, and `"shutdown"`.

### Run Automatically on Startup

In general, you will probably want the server program (e.g. Uvicorn) to be started automatically on server startup, and without needing any **human intervention**, to have a process always running with your API (e.g. Uvicorn running your FastAPI app).

### Separate Program

# OpenAPI Webhooks

There are cases where you want to tell your API **users** that your app could call *their* app (sending a request) with some data, normally to **notify** of some type of **event**.

This means that instead of the normal process of your users sending requests to your API, it's **your API** (or your app) that could **send requests to their system** (to their API, their app).

This is normally called a **webhook**.

## Webhooks steps

The process that happens when your API app calls the *external API* is named a "callback". Because the software that the external developer wrote sends a request to your API and then your API *calls back*, sending a request to an *external API* (that was probably created by the same developer).

But you should first read the **Tutorial - User Guide** (what you are reading right now).

3. Install Poetry in this Docker stage.

4. Copy the `pyproject.toml` and `poetry.lock` files to the `/tmp` directory.

    Because it uses `./poetry.lock*` (ending with a `*`), it won't crash if that file is not available yet.

5. Generate the `requirements.txt` file.

6. This is the final stage, anything here will be preserved in the final container image.