Re: Using lookupService()

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Hello Mike,

> PeerGroup.lookupService() is designed to return a reference to a local
> instance of a running service. It's not capable of finding service
> instances running on other peers.

I hoped so ...

> There is no built-in API for finding service instances running on other
> peers. Commonly a pipe is used for service instance location. All
> instances of the service will listen on a well-known pipe and peers can
> locate instances by opening an output pipe and sending a contact
> request. One or more instances of the service should respond to the
> client and the client will then establish a connection to one of the
> instances.

That's exactly what I wanted to know! All examples I've seen use pipes
and pipe advs, and I always wondered where service instance come into
the game. But seems like I have to do my own RMI/RPC-like communication
here (the JXTA-RMI project looks kinda ... dead).

> Depends on what the advertisements are for. If you are adding your
> service to the peer group implementation then you need to publish the
> service module implementation, peer group module implementation
> advertisement (and the class and spec advs) into the peer group in which
> you will be instantiating your peer group.

OK, I'll try that.

> If you are publishing the impl advertisements into your peer group then
> peers which want to instantiate your peer group can't access them. It's
> a chicken and egg problem. They need the advertisement to instantiate
> the peergroup but can't get it because the peergroup is not instantiated.

Sounds reasonable...

> I'm not sure I follow. Are these two services part of the same peer
> group? Or the same service running on two different peers? You should
> also make sure you are running with Log4J INFO level in order to better
> see what's happing

Both are running on the same peer in the same peer group (I'm doing
exactly the same with both class, spec and impl advs). Seems like I have
to start debugging here... (I hoped I didn't have to :( )

> Yes, your application needs to call newgroup.startApp(). What do you
> mean by "join" in this case. Do you mean MembershipService.join() or
> something else?

Yes, so that the peer who created the group also joins it (= becomes a
member of that peer group). I think I remember reading, that the peer
who creates a peer group automatically joins it, but I'm not sure about
that.

Thanks a lot!!
Daniel
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