[Twisted-Python] suggestions needed on a process output event

[Yun Mao]

Hi. I'm a new to twisted python (and python) and found that they are 
really interesting! I have several questions:
1. Can a reactor listen on several ports at the same time?
2. How to add some special event? For example, I have a process running: 
say "tail -f /var/log/messages". I wish, each time, when the process 
outputs a new line, my protocol could receive such an event (like 
dataReceived), and I can get that new line as my data. How to implement 
this?

Thank you very much!
--yun