Suggestions Requested

This is a request for Suggestions or opinions. I'm using Joomla! 3.2.3 with CBSUBS v3.0.0 with v6.0.0 of Vtiger. Also the system is hosted on a GoDaddy linux server. My intent is to use Joomla to sell subscriptions via CBSUBS for the Vtiger CRM system. I've put together the integration software that creates and/or updates the user in Vtiger and returns the Vtiger user_id back to CB to be recorded in the CB users table.

Now here's where I'm soliciting opinions. To accomplish all this it looks like I’ll need execute a block of code once the subscription has been paid for and then again when the subscription lapses. What's the best practice for approaching this? I want to make sure the system is upgradeable, but I need the seamless approach to creating the user account in Vtiger.

You can use CBSubs URL to execute a PHP file via HTTP request that has all your API in it or you can use CB Auto Actions and its Code action with Method set to PHP on the various CBSubs triggers to execute inline PHP. I don't know specifically what PHP you need to execute and if it's a part of the 3rd party system outside of Joomla then you'll probably want to use the HTTP request approach.