DirectMethod Post Reqeust body limit

hi


When i call DirectMethod(public) , request send body with all combobox data
like " &combobox-112=&combobox-113&~~~&directmethodname"

but DirectMethod(static public) don't have combobox data.
it only have function parameter data

And when i call directmehtod(public) in client-side, DirectMethod don't work in server-side
but directMethod(static public) work


is have limit of request parameter? because my page have a lot of combobox


can i get some detail reference about DirectMethod ?


thanks