# core
## Port management
Before starting, boopiter checks who owns the target port:
[`_port_owner`](https://drscotthawley.github.io/boopiter/core.html#_port_owner)
pings it to tell a running boopiter from someone else from nobody, and
[`_kill_port`](https://drscotthawley.github.io/boopiter/core.html#_kill_port)
frees a port held by a *previous boopiter* run – so relaunching is safe
but an unrelated service is never killed.
## Tailwind precompile
[`_build_tailwind`](https://drscotthawley.github.io/boopiter/core.html#_build_tailwind)
compiles a static Tailwind CSS file once at launch, replacing the CDN’s
in-browser JIT compiler – faster page loads and no runtime CDN
dependency.
## Launching
[`launch`](https://drscotthawley.github.io/boopiter/core.html#launch)
ties it together – free the port if it’s ours, build the CSS, start the
server. It’s the `@call_parse` entry point exposed on the command line.
------------------------------------------------------------------------
source
### launch
``` python
def launch(
nbfile:Annotated=None, # .ipynb file to load on startup
port:int=8000, # the port to serve boopiter on
no_auth:bool=False, # skip token-gating the server -- ONLY on a network you fully trust; every code cell already runs with this process's own permissions, so an unauthed boopiter is equivalent to handing out a shell
):
```
*Launch (or relaunch) the boopiter server; refuses to touch a port held
by something that isn’t boopiter*