Using the DistributedCommandBus with JGroups

Imported from Google Groups
1

Hi all,

I have been trying to follow section 3.6 of the Axon user guide, “Distributing the Command Bus”, but to no avail. I am using the Spring Framework and thus the JGroupsConnectorFactoryBean. The JGroupsConnector never finds other members of the cluster; it prints that it is connecting to the cluster, but then each individual machine running the software seems to makes a cluster of one with itself and commands are not distributed. I’ve tried several XML files to configure JGroups to find each other, but no luck there. I have used the McastReceiverTest and McastSenderTest provided by JGroups to verify that my networking between machines using IP multicast is functional.

Does anyone have a working example of a configuration for the DistributedCommandBus with the JGroupsConnector they can share, including the XML file for JGroups configuration?

Thank you,
James

2

Hi James,

JGroups is easy when it works. Until then, it’s another story.
There is a sample in the Axon sources: https://github.com/AxonFramework/AxonFramework/blob/master/quickstart/src/main/java/org/axonframework/quickstart/RunDistributedCommandBusWithSpring.java

The xml file used is here:
https://github.com/AxonFramework/AxonFramework/blob/master/quickstart/src/main/resources/tcp_gossip.xml

Note that IPv6 doesn’t always work. Setting the system property: java.net.preferIPv4Stack=true at startup helped for me.

Hope this helps.
Cheers,

Allard

3

How should one configure the IP addresses? In particular:

bind_addr="${jgroups.bind_addr:127.0.0.1}"
bind_port="${jgroups.bind_port:7800}"

<TCPGOSSIP initial_hosts="127.0.0.1[12001]" timeout="1500"/>

Do these configuration values vary across machines?
4

James,

It reminds my difficulties with configuration.

I outlined some messy but working examples (progressively extended from quickstart by copying-and-pasting):

5

Hi James,

I’ve recently published a small Axon + JGroups + Docker demo here: https://github.com/mrook/axon-jgroups-docker-demo

Note: this demo is based on the latest 3.0 milestone.

Regards,

Michiel