how to determine the way call from my native asp.net application or WCF service

[architectsd]

I have an asp.net application which calls a Business layer directly, And the same business layer is exposed as a WCF service so that some other applications (external website / console app) can consume it. In my BL i want to determine whether the call is from my native asp.net application or it is coming through WCF call, Is there any foolproof way of determining this without passing extra parameters ?