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discovering a specific peer

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apprenticegcc
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Joined: 2006-08-23

My goal is for a JXTA peer to discovery a specfic set of perviously known peers. The peers may be widely dispersed across the global JXTA network.

Does the JXTA Peer Discovery mechanism (J2SE implementation) have a way to say: "go discover this peer [PEERID or IP address]"?

As far as I can tell, the Peer Discovery mechanism unicasts on the local network and crawls known Rendezvous peers looking for any peers.

How can I prompt it to look for a specific peer if there's no garuntee that it is 1) on the same local network or 2) on nearby Rendezvous peers?

Does JXTA cache transport layer (aka IP addresses) of the last known location of previously encountered peers. I know it caches the JXTA Peer ID.

Alternatively, is the best approach to have both peers try to discovery & join a shared JXTA Peer Group? If so, how does one go about instantiating, publishing, discovering, etc. the peer group? I'm confused mainly as to which peer does what in which order.

Thanks beforehand!

P.S. If my questions are too basic, etc. can you point me to references that cover such topics or fundamental concepts that would answer my line of questions?

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tra
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Joined: 2003-06-16

> My goal is for a JXTA peer to discovery a specfic set
> of perviously known peers. The peers may be widely
> dispersed across the global JXTA network.
>
> Does the JXTA Peer Discovery mechanism (J2SE
> implementation) have a way to say: "go discover this
> peer [PEERID or IP address]"?
Yes. You can specify a peer ID or peer name
>
> As far as I can tell, the Peer Discovery mechanism
> unicasts on the local network and crawls known
> Rendezvous peers looking for any peers.
Yes. JXTA uses a Distributed Hash Index service (SRDI) to route discovery queries within the JXTA Rendezvous peerview network.
>
> How can I prompt it to look for a specific peer if
> there's no garuntee that it is 1) on the same local
> network or 2) on nearby Rendezvous peers?
The JXTA discovery service relies on the SRDI
index to route queries within the JXTA network. Peers
don't have to be on the same local network and be connected to the same rendezvous to find each others. SRDI
will route the queries to right rendezvous.

>
> Does JXTA cache transport layer (aka IP addresses) of
> the last known location of previously encountered
> peers. I know it caches the JXTA Peer ID.
Yes. The JXTA routing service maintains a cache
of the last know mapping between a peer ID and
its IP address.

>
> Alternatively, is the best approach to have both
> peers try to discovery & join a shared JXTA Peer
> Group?
JXTA peergroups are scoped virtual network domains

>If so, how does one go about instantiating,
> publishing, discovering, etc. the peer group? I'm
> confused mainly as to which peer does what in which
> order.
Peergroups are represented as peergroup advertisements.
You can have both peers either search for the peergroup advertisement and join the groups, or you can predefine
your peergroup advertisement in each peer application and
just have the peers join the peergroups. It does not matter which peers join first.

>
> P.S. If my questions are too basic, etc. can you
> point me to references that cover such topics or
> fundamental concepts that would answer my line of
> questions?
You should look at some of the tutorial and programmer's guide (http://www.jxta.org/Tutorials.html)

Hth,

B.