flow in general

[Oguz Yarimtepe]

I was analyzing an http flow that is converted from a tcpdump file. I
was using racluster. I saw the flows generally uni-directional. Some are
bi-directional. I checked the meaning of directionality again from here,
but i didn't get the point indeed. 

For ex when i see a bi-directional flow does that mean that every
package is from source to destination? Why is some http flows uni and
some bi directional?

I will be happy if someone give more detail about directionality. 

And is there any #argus channel on irc, so that we can join and ask some
questions there also?

Oğuz