Suppose a user A wants to feed a certain smart contract F with some data d that can be obtained from an oracle O.

What is the usual workflow in the most popular oracle solutions?

I imagine, A sends a request to a smart contract monitored by O (and a certain fee for example) specifying that d has to be sent to F, then O writes d directly on F.

As an alternative, O may send d to A, then A sends d to F and F verifies some signature proving that d is actually coming from O.