Google Calendar Integration

we have developed a java crm integrated with our ERP and we would like to connect it with google apps: when a user of CRM inserts, updates, or deletes an event or task we wrote in a mysql database and we would like it to be shown on the google calendar of the user (we have email address or calendar name). We have fully access to the data on sql database and have all authority over them, we have access to any folder on Web server, available google account for GOOGLE API if necessary.