I can update my status/Avatar using presnece and Vcard classes too... does this mean in this case the subscribers will nto be notfied ???
Yes, but for this case, there's http://xmpp.org/extensions/xep-0153.html
Unfortunately XMPP is not very clear here, and offers 2 possibilities, due to historical reasons.
Also i was readiing about PubSub and i see there are Node , collection nodes etc... the XMPP.org doesnt have details abt the node and other pubsub components do you know here can i read the details abt the same ..
All I know is the spec (which is probably the most complex one and not easy to understand).