Environment consists of one server node and several client nodes. When new client node joins group I should call some remote method on it from server node.

Client node source code:

import org.jgroups.*;
import org.jgroups.blocks.RpcDispatcher;

public class Client extends ReceiverAdapter{
public void start() throws Exception

{ JChannel channel = new JChannel(); RpcDispatcher dispatcher = new RpcDispatcher(channel, this, this, this); channel.connect("cluster"); }

public String doIt(String arg)

{ System.out.println("Client called: " + arg); return arg; }

public static void main(String[] args) throws Exception

{ new Client().start(); }

}

Server node source code:
import java.util.*;
import org.jgroups.*;
import org.jgroups.blocks.*;
import org.jgroups.util.*;

public class Server extends ReceiverAdapter{
JChannel channel;
RpcDispatcher dispatcher;

public void start() throws Exception

{ channel = new JChannel(); dispatcher = new RpcDispatcher(channel, null, this, this); channel.connect("cluster"); }

public void viewAccepted(View view){
try
{
System.out.println("view accepted: " + view);
if (channel.isConnected())

{ callClients(view); }

}
catch (Throwable e)

{ e.printStackTrace(); }

}
public void callClients(View view) throws Exception{
MethodCall call = new MethodCall("doIt", new Object[]

{ "Hello world" }

, new Class[]

{String.class}

);
RspList<String> rsp = dispatcher.callRemoteMethods(filter(view.getMembers()), call, new RequestOptions(ResponseMode.GET_ALL, 10000));
for (Map.Entry<Address, Rsp<String>> pair : rsp.entrySet())

{ System.out.println(pair.getKey() + " -- " + pair.getValue().getValue()); }

}
public Collection<Address> filter(Collection<Address> addresses){
Collection<Address> result = new ArrayList<Address>();
for (Address address : addresses)
{
if (!address.equals(dispatcher.getChannel().getAddress()))

{ result.add(address); }

}
return result;
}
public String doIt(String arg)

{ System.out.println("Server called: " + arg); return arg; }

public static void main(String[] args) throws Exception

{ new Server().start(); }

}

If client node is started before server one everything work as expected.
But when server node is started before client one I observe following
in stdout from server node:

Sep 16, 2011 5:15:54 PM org.jgroups.logging.JDKLogImpl info
INFO: JGroups version: 3.0.0.CR1
Sep 16, 2011 5:15:54 PM org.jgroups.logging.JDKLogImpl warn
WARNING: receive buffer of socket java.net.DatagramSocket@7c6572b was
set to 20MB, but the OS only allocated 65.51KB. This might lead to
performance problems. Please set your max receive buffer in the OS
correctly (e.g. net.core.rmem_max on Linux)
Sep 16, 2011 5:15:54 PM org.jgroups.logging.JDKLogImpl warn
WARNING: receive buffer of socket java.net.MulticastSocket@6e84cc09
was set to 25MB, but the OS only allocated 65.51KB. This might lead to
performance problems. Please set your max receive buffer in the OS
correctly (e.g. net.core.rmem_max on Linux)

-------------------------------------------------------------------
GMS: address=andrey-8222, cluster=cluster, physical address=10.0.1.197:65216
-------------------------------------------------------------------
view [andrey-8222|0] [andrey-8222]
connected true
method called
[]
view [andrey-8222|1] [andrey-8222, andrey-63112]
connected true
Sep 16, 2011 5:16:17 PM org.jgroups.logging.JDKLogImpl warn
WARNING: andrey-8222: failed to collect all ACKs (expected=1) for view
[andrey-8222|1] [andrey-8222, andrey-63112] after 2000ms, missing ACKs
from [andrey-8222]
method called
[]
andrey-63112 – null
Server called: Hello world

I'm confused by the following:

• server nodes tries to receive ACKs from itself (missing ACKs from [andrey-8222])
• rpc dispatcher calls server node (Server called: Hello world)

I can work around this issue by doing rpc call in separate thread. By in this case I sometimes receive null as call result from some nodes with following messages in client logs: no physical address for xxx.

Also I have some general questions about RPC dispatcher:

• are rpc calls supported during view update?
• what conditions I should wait for in order to guarantee rpc dispatcher's correct behavior?