I have done this via direct connection with our Oracle ebs database through setting up the Data Source in Tableau. It is possible, but not necessarily the best practice.
This reply is a bit late, but if you're still looking for connectivity to Oracle E-Business Suite, I can help. I'm a product manager for Magnitude, a Tableau partner. We have a product, Magnitude NoetixViews that creates a layer of business views on top of the Oracle E-Business Suite database that insulates you from the problems that can happen when you connect directly, as Alyssa alluded to. We also have an integration product named Magnitude Noetix Generator for Tableau, which provides business-friendly access to NoetixViews from Tableau.
Feel free to reach out to me at firstname.lastname@example.org if our solution sounds like it will meet your need. I can go into more detail and show you a demo.