Running an External Routine


I'm wondering what kind of code would be required to run an external routine after certain things. For example, let's say that we want to provision something external when a user subscribes to a certain external service (using the Upgrades plugin), and we need to run a POST command to provision it.

So, in summary, the process would be something like:

- User subscribes to upgrade
- Upon subscription (or receipt of payment), POST command (or other external command) is run
- Some mechanism (maybe a database flag) logs the fact that the external command has been run, so it's not run again.