Re: [circle] short technical questions about Circle, and info about win32

[Paul Campbell]

On Fri, Aug 20, 2004 at 04:15:41PM +0200, Philippe Froidevaux wrote:
> Hi,
> 
> >>- does Circle manage nodes localisation ? I mean, if a set of node 
> >>hold an information, the application will get it from the node 
> >>closest to me. 
> >
> >
> >I do not understand what you mean by that...
> >does your question refer to the DHT queries,
> >or to the process of downloading a file?
> >
> >>P2P:
> >>- does Circle manage DHT replications, in the way of Pastry and Past ? 
> >
> >
> >I do not know either.
> >I mean, I know very well what circle does, but
> >I do not understand your terminology.
> 
> 
> I try to explain with my poor english and poor Circle knowledges :
> 
> DHT : Distributed Hash Table. A node has a unique identifier, and 
> storing a key/value pair on the ring will store it on the node wich has 
> an ident closed to the key. I suppose Circle works on the same basis, 
> right ?

Yes. It is the Chord protocol.

> by "replication", I mean : if you store a hash on your DHT, the system 
> will automatically (or uppon request) copy this key/value on the 'k' 
> nearest nodes. Then, if one node fails, the other will keep the value. 
> Some systems are able to guarantee that always 'k' nodes store the hash, 
> by automaticaly propagating the replication in case of nodes failure.

Yes. It stores a distributed cache across the entire system. The cache will
replicate the same data at K points equidistant around the entire DHT
circle. This is better than the system you refer to since the system you
are referring to localizes everything to one arc along the circle.

> by "localisation", I mean : the system take care of the "distance" 
> between nodes. The distance is a set of number, like : network speed, 
> network geographical proximity, network bandwidth, etc. In this way, if 
> you have a key/value pair replicated on the ring and you're asking for 
> this value, the "closest" node will answer.

No. Not yet. It does not do PNS (proximity neighbor selection), at least
at the DHT level.