[p2p-hackers] A Question about user awareness in p2p

[Anoop Mavilaveettil]

Well it is not that simple.
1)First, it is not necessary or mandatory that "two people are always
in each other's buddy list". A user might have added another user in
his buddy list, but not the other way. In this case when the second
guy comes online, the first guy would never get a notification.
2)Second. One major issue, that I have to point out, is that  I'm not
talking about peers, I am talking about users. A user can connect to
the p2p net using any peers.

Let me explain a common scenario
a) User1 connects to the p2p net using peer1.
b)User2 connects to the p2p net using peer2.
c)User1 using common message mechanisms add user2(NOT PEER2) as his
buddy. But the main thing to note, is that User2 doesn't even
know/don't care to know about user1 adding him to buddy list and user2
never adds user1 in his buddy lists.
d)User2 disconnects from the p2p net. At this time, we can possibly
have some notification mechanisms, which will notify user1 at peer1 about
the disconnection of user2.
e)User2 connects to the p2p net from peer3. ---> And here lies my
issue. How would user1 at peer1 would know about the arrival of
user2 at peer3( without structured or limited flooding?)
NAT traversal and all other issues are lower level ones, and solutions
for those issues are well documented and easily available on the web.


On Tue, 22 Mar 2005 19:17:12 +0100, Markus Kern <markus-kern at gmx.net> wrote:
> 
> On Tuesday, March 22, 2005, 7:00:55 PM Anoop Mavilaveettil <anoopsmv at gmail.com> wrote:
> 
> > Thanks Mike and Greg,
> >  Yes I had known that I would have to(and was planning to) use DHT for
> > peer discovery. But the issue I had was about a peer getting a
> > notification when another specific peer comes online.
> > As Greg said, this would have involved polling DHT for this info, and
> > if the buddy system is very well connected(I  mean a majority of the
> > peers have buddies), then this polling could become a bottleneck.
> > See the issue of, say, figuring out if "my" buddies are connected to
> > the p2p net when "I" come online is what that could be solved by DHT.
> > But I was and is looking a solution for is the issue of "I'm already
> > connected and now how would "I" know when one of my buddies come
> > online?".
> 
> I we assume that two people are always in each others buddy list a
> person who comes online can look up all his buddies on the DHT and send
> them a direct notification that he is online. Except for some
> complications when both parties are firewalled (which would require a
> solution anyway if you want to do anything useful) I see no problems
> with this approach. Am I missing something?
> 
> --
> Markus Kern
> 
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