How to determine who made changes?

I add/update the Address Book/phones/email/who's who tables using 2 ways, they are web services and the JDE application. In their table triggers, I only want to execute a business function if these changes are done in the JDE application. 

If the changes are done using web services then I DON'T want to execute the business function in these table triggers. Is there an elegant way to do this? Thanks