Soap request serialization

Question

Hi 

I have a wcf service in that i have some methods e.g: 

public FOSResponse GetTransactions(UserSession usersession, TransactionEnquiryRequest TransactionEnq)

 {

   // heere i want to serialize the request to write it in my log file

   // how can i get the whole request string or xml. i want to write in the log that what comes when send a request       to  GetTransactions method.

}

 

Thanks,