You want to use discovery on the data portal endpoint? That's probably not a great idea, since the data portal is an n-tier client/server architecture, not an open SOA model.
If you want an open SOA model, you should follow the guidance in Chapter 21 of the Expert 2008 Business Objects book. The resulting services you create can support whatever WS-* or other standards (such as REST) you'd like to implement.
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