To prepare a service for registration with Plesk Notifications, create a PHP file containing a class that implements interface *Plan_Item_Interface* and put the file into a directory available to Plesk. The directory must have a unique name and reside in `/PRODUCT_ROOT_D/admin/plib/`, where `PRODUCT_ROOT_D` is the installation directory of Plesk. When designing names of the class that implements the interface and the file that includes this class, follow Zend naming conventions. For example, if you create a directory `/PRODUCT_ROOT_D/admin/plib/servicedir` and put there file `servicefile.php`, then the class name must be *servicedir_servicefile*. To learn more about the naming conventions, see http://framework.zend.com/manual/1.12/en/coding-standard.naming-conventions.html. We offer a sample class you can use as a base when writing own classes to help you with the implementation. The code is supplemented by comments that explain the interface organization. To view the code, click the following link: code sample.