Question

How? Is it possible? If not what are my alternatives?

May be python daemon?

Edit: My aim is to play with custom protocols in the internet (online).

Answer 1

There are two aspects to be considered here:

1. does your shared hosting provider allow you to run daemons? Most probably not, in that case a cron task might be an alternative solution.
2. How to technically create a daemon? There’s a PEAR package that, at least for Linux, does whatever’s needed to convert your script to a daemon.

Now, some webhosters don’t even offer cronjobs, in that case using an external service like setcronjob that’s configured to regularly call a php script on your website can be used as a last alternative to switching hosters.