what is the best Google Calender application for unity to alert and notify you with Events?

i want some example for the best application/client for manage and edit and control your Google calendar and daily mission or event.

and it provide alert -alert with sound or notification- to give you more attention for your important work ?

According to this thread. Mozilla Sunbird with the GCALDaemon is what you're looking for. But I believe development is going to be stopped on sunbird, so maybe Thunderbird with the Lightning calendar addon might be best.

Here i suggest Sunbird is your the best application/client for manage and edit and control Google calendar and daily mission or event.

you can use evolution calendar. You can directly see the events in the date and time applet of unity panel from evolution calendar. You can synchronize the calendar with any online calender like Google calender or Facebook event.
I think evolution is not by default installed in Ubuntu now but you can install it from synaptic package manager or from Ubuntu software centre. When configuring you can skip the email configuration part and directly go to calender.
All the best