I have a Hazelcast cluster with multiple nodes, each consisting of identical instances of a "Daemon" server process. These daemons are Java applications with embedded Hazelcast caches as well as logic that forms the core of my platform. I need to distribute certain events on the platform to listeners across the cluster which can reside in any (or all) of the connected nodes. From my reading of the documentation it seems to me that if I attach an EntryEventListener to the maps on daemon startup then whenever the event happens in that map my callback will be called in every running instance of the daemon.
What I would like is for the callback to be called once (on any single node) across the cluster for an event. So if I have 10 nodes in the cluster, and each node registers an EntryEventListener on a map when it joins I would like any single one of those listener instances (on any of the nodes) to be triggered when that event happens and not all of them... I don't care which node listener handles the event, as long as it is only a single instance of the listener and not every registered listener. How can I do this?
I saw this old question which sounds like the same question, but I'm not certain and the answer doesn't make sense to me. hazelcast entry listener on a multinode cluster
In The Hazelcast documentation there is this:
There is also another attribute called local, which is not shown in the above examples. It is also a boolean attribute that is optional, and if you set it to true, you can listen to the items on the local member. Its default value is false.
Does that "local" attribute mean that the event would be triggered only on the node that is the primary owner of the key?
Thanks, Troy
Yes, setting local to true will make the listener to fire events only if the member is the primary owner of the key. You can achieve what you want using local listeners