I am looking for an alternative of Google Drives that works/installs in Ubuntu server. Something similar that offers the same or most of the functions in Google Drive, like file upload, syncing, sharing files, etc..
Note that I am not looking for a client to connect to Google Drive like Grive. I am looking for a server or service that can be installed in Ubuntu Server and that it resembles the way Google Drive works with documents and user groups.
For better understanding of what I am looking for, we can see http://owncloud.org/ which has options like Calendar, events, contacts and other stuff that anybody that has used Google Drive for documents will know.