init members

Change-Id: I3ee5d05142ebd9738e34ea3276932a4f9e3fc43d
the stream is already owned by the root storage

Change-Id: If4c548c1ed9275f525fe311853545af3f6313f41
add a brief description

Change-Id: I1469910e3c20248133e56145c9ea543cbfdf3c4a