Hello,
the web client switches from streaming to smart polling mode after a timeout if no data was received from the opened streaming session.
from
http://www.lightstreamer.com/products.htm :
Stream-Sense and Smart Polling
If a client is connected through a network infrastructure that blocks any form of streaming, then Lightstreamer is able to send the updates via a smart polling mode. The Web Client of Lightstreamer automatically detects if streaming is not supported (through the Stream-Sense feature) and in this case it switches to smart polling mode.
Note that you can configure the smart polling behavior:
http://www.lightstreamer.com/docs/client_web_jsdoc/Policy.html
Smart polling is also known as long-polling.
See also:
http://cometdaily.com/2007/12/05/easing-into-comet/