Give a parameter to a webapp?

Hi everybody,

I want to know if somebody has ever transmitted a parameter to a webapp...
My issue is: i have a webapp on a page. i access this page throught 2 
pages. The webapp must have a behavior different (a filter on a request 
in my webapp..) according to the page that has "called" the page where 
the webapp is...
So i want to know if there is a way to act between Jahia and a webapp...

Thanx a lot,

Guillaume