Oh now I see - the key point obviously is the ability to extract only the required information from the stream not to thrpw the full data content onto the "reader" - and that happens "real time". Correct?
Kinda yes. Take a (bad) example: you know that when a relay closes your data stream burps. You put your ear to the realy and your finger on the stop button. Then, after the stop you only have to look at the last few records instead of the wule 4711 pages of records.

Erik