ASP.NET - automatically logout notation of facebook in asp.net

hi,

i have develope the appliation base on facebook.base on facebook authentication is true our appliction will work. if face book is closed(log-out). out application also closed.

here i need the  facebook connectivity state on each time. if connectivity close in fb.in my application also. close.

please help me.

how can i achieve this.

thanks in advance.