axon-jgroupsmodule is available on the classpath through the preferred dependency management system. When combined with Spring Boot, the
axon-jgroups-spring-boot-starterdependency can be included to enable auto-configuration.
JGroupsConnectoracts as both a
NoteYou can find the JGroups specific components for the
JGroupsConnectorhas four mandatory configuration elements:
channel- which defines the JGroups protocol stack. Generally, a JChannel is constructed with a reference to a JGroups configuration file. JGroups comes with a number of default configurations which can be used as a basis for your own configuration. Do keep in mind that IP Multicast generally doesn't work in Cloud Services, like Amazon. TCP Gossip is generally a good start in such type of environment.
clusterName- defines the name of the cluster that each segment should register to. Segments with the same cluster name will eventually detect each other and dispatch commands among each other.
localSegment- the Command Bus implementation that dispatches Commands destined for the local JVM. These commands may have been dispatched by instances on other JVMs or from the local one.
serializer- used to serialize command messages before they are sent over the wire.
NoteWhen using a cache, it should be cleared out when the
ConsistentHashchanges to avoid potential data corruption (e.g. when commands do not specify a
@TargetAggregateVersionand a new member quickly joins and leaves the JGroup, modifying the aggregate while it is still cached elsewhere.)
JGroupsConnectorneeds to actually connect in order to dispatch messages to other segments. To do so, call the
NoteNote that it is not required that all segments have command handlers for the same type of commands. You may use different segments for different command types altogether. The distributed command bus will always choose a node to dispatch a command to that has support for that specific type of command.
JGroupsConnectorFactoryBean. It automatically connects the connector when the
ApplicationContextis started, and does a proper disconnect when the
ApplicationContextis shut down. Furthermore, it uses sensible defaults for a testing environment (but should not be considered production ready) and autowiring for the configuration.