+The relay ensures that it sends only ready ctf traces, so once this command is
+complete, V knows that it has all the streams ready to be processed.
+A quick note about the "sessions": from the relay perspective we see one
+session for each domain (kernel, ust32, ust64) of a session as created on the
+sessiond. For example, if the user creates a session and adds events in the
+kernel and UST and has only 64-bit applications running, the relay sees two
+sessions with the same name and hostname. So in order to display a session as
+seen by the user, the viewer has to attach to all the sessions with the same
+hostname and session name. There might be clashes if two servers on the network
+have the same hostname and create the same session name, but the relay cannot
+distinguish these cases, so it is currently a known limitation.
+During a session, new streams might get added (especially in per-pid tracing)
+so the viewer must be ready to add new streams while processing the trace. To
+inform V that new streams are available, R sets the
+LTTNG_VIEWER_FLAG_NEW_STREAM flag on LTTNG_VIEWER_GET_NEXT_INDEX and
+LTTNG_VIEWER_GET_PACKET replies. The viewer must then issue the
+LTTNG_VIEWER_GET_NEW_STREAMS command and receive all the streams, just like
+with the attach command.