Accessing JGroups Channels Within a JBoss 7 Application

[safetytrick]

I'm in the process of upgrading a JBoss 5.1 application to JBoss 7.1.1. We currently monitor cluster health by looking into JGroups JChannels and comparing the view that's expected from the current cluster state and the actual JGroup's view. I'd also like to create my own JGroups channel and use it for some cluster coordination. What I can't seem to find is any JBoss API for current open channels and the ChannelFactory? Is there any way to access the underlying JGroups subsytem?

Michael

[pedrokowalski]

I'll bump this question.

Is it possible to access the JGroups from the application? I would like to reuse the protocol stack and use it to create the JChannel.

All the best,

Piotr

[pferraro]

From a service activator:

{code}public class MyService implements Service<Void> {
    private final Value<Channel> channel;
    public MyService(Value<Channel> channel) {
        this.channel = channel;
    }
    @Override
    public void start(StartContext context) {
        try {
            this.channel.getValue().connect("myCluster");
        } catch (Exception e) {
            throw new StartException(e);
        }
    }
    @Override
    public void stop(StopContext context) {
        try {
            this.channel.close();
        } catch (Exception e) {
            // Log exception
        }
    }
    @Override
    public Void getValue() {
        return null;
    }
}
public class MyServiceActivator implements ServiceActivator {
    @Override
    public void activate(ServiceActivationContext context) {
        String stack = "udp";
        String channelId = "mychannel";
        ServiceName channelName = ChannelService.getServiceName(channelId);
        InjectedValue<ChannelFactory> factory = new InjectedValue<ChannelFactory>();
        context.getServiceTarget().addService(factoryServiceName, new ChannelService(factory))
                .addDependency(ChannelFactoryService.getServiceName(stack), ChannelFactory.class, factory)
                .install()
        ;
        ServiceName name = // Some service name
        InjectedValue<Channel> channel = new InjectedValue<Channel>();
        context.getServiceTarget().addService(name, new MyService(channel))
                .addDependency(channelName, Channel.class, channel)
                .setInitialMode(ServiceController.Mode.ACTIVE)
                .install()
        ;
    }
}{code}

You'll then need to create a META-INF/services/org.jboss.msc.service.ServiceActivator file containing the fully qualified class name of your service activator class and add the following dependencies to your application's META-INF/MANIFEST.MF:

{code}Dependencies: org.jboss.msc, org.jboss.as.clustering.jgroups, org.jgroups

That should do it.

[pedrokowalski]

Thanks a lot Paul for your post and talk!

I've managed to get it working and summed this up in my post here: http://piotrnowicki.com/2013/02/using-jgroups-directly-from-jboss-as-7-component/

Hope it'll help someone else.

Cheers!

[belaban]

https://issues.jboss.org/browse/JGRP-1613 will make is even simpler to reuse an existing channel, either from Infinispan or Wildfly. This will not only give you an independent channel (ForkChannel), on which you only see your *own* traffic, but you'll also be able to add protocols to an existing stack, e.g. COUNTER.

This is being designed and implemented as I speak (Aug 2013)...