Connecting Java-based Machine Learning Package/Lib to PHP and MySQL

I want to connect the Datumbox machine learning framework to a MySQL database using PHP. Datumbox is an open-source Machine Learning Framework written in Java. Currently Datumbox offers the API Client for PHP using REST JSON, but I want to use the application like a library/package without using their API. Could you please give me some help/guide about how to solve this problem?