Thank you andypiper very much. This clearly answers the first question.
Still, who is the resource owner, when I using the Streaming or Rest API?
Both the spec of OAuth v1 and OAuth v2.0 use this concept.
I have the hunch that my problem with this concept of a resource owner might
be down to the fact that the specs of both OAuth 1 and 2.0 do and can not
consider the many possible ways to use this authorization framework.
So the terminology does not really reflect the actual use of OAuth. For instance,
both specsonly talk about 3rd party apps. However, when I use the REST or
streaming API of Twitter, I develop an app for me, and thus a 2nd party app, right?
A similar misfit might apply to resource owner.
What do you think?