PHP Point Of Sale can interact with other applications via webhooks. Webhook requests are configured in store config. We have web hooks available for many actions such as creating a customer.
Once you configure a URL in store config for a web hook. An http request is sent with all the data that was just created in the POS. Here is an example way to parse the web hook request
$jsonStr = file_get_contents("php://input");
$json = json_decode($jsonStr);