What does it take to implement a chat system in Python (Not asking for code just advice before I start my little project)

[Aseem Bansal]

@vikash agrawal

About GUI I discussed it at https://groups.google.com/forum/#!starred/comp.lang.python/M-Dy2pyWRfM and I am thinking about using PySide 1.2 for clients of chat system. I think I'll need downloadable clients if I want to make something like google talk. Then I'll need to implement server side programming also. I think google app engine would be suitable for this as it is going to be always online.

In the above scenario I wanted to know whether the database can be stored on google app engine itself? Is it possible? Having a chat system with server online and DB offline isn't going to be good. Should I consider heroku for this or can it be done using google app engine? Is it viable to have the DB on google appengine itself?

About using web frameworks, in the above scenario when there isn't an online website for chat would I need web frameworks? I am confused about this. Can server side programming be done in Python or by using a web framework only?