Sending messages across cluster

[gmile]

Right now libcluster doesn't seem to be able to send messages across cluster. From what I can tell after looking at :publish implementation, the event is only sent to subscribers, which are processes on that same node, but not nodes in cluster (correct me if I'm wrong).

I am using epmd strategy. The way I'm testing it is this:

1. Run nodes:

   $ iex --sname node1@localhost --cookie test_cookie -S mix
   $ iex --sname node2@localhost --cookie test_cookie -S mix

2. Connect nodes:

   iex(node1@localhost)1> Cluster.Strategy.connect_nodes([:'node2@localhost'])
   iex(node2@localhost)1> Cluster.Strategy.connect_nodes([:'node1@localhost'])

3. Subscribe both shells to cluster events:

   iex(node1@localhost)2> Cluster.Events.subscribe(self())
   iex(node2@localhost)2> Cluster.Events.subscribe(self())

4. Publish event from within node1:

   iex(node1@localhost)3> Cluster.Events.publish({:ok, "Hello, world!"})
   
   15:04:34.703 [debug] [libcluster] [events] <== {:publish, {:ok, "Hello, world!"}}
   :ok
   

5. Flush shell messages on both nodes:

   on node1:

   iex(node1@localhost)4> flush()
   {:ok, "Hello, world!"}
   :ok
   iex(node1@localhost)5>
   

   and on node2:

   iex(node2@localhost)3> flush()
   :ok
   

Was this done by design? If so, what is the purpose of publishing events within the same node?

At the same time nodeup and nodedown events work perfectly across the cluster.

Is there a plan to support publishing arbitrary events across cluster? If so, I'd like to work on a PR to bring this support.

[bitwalker]

I've removed Cluster.Events from libcluster as part of the 2.0 effort to bring libcluster into alignment with firenest. libcluster is really intended to only provide the means by which you cluster nodes, beyond that though, things like firenest will be where you go for distributed pub/sub. Currently, swarm can work as a distributed pub/sub library, but firenest is going to be a better solution for that when it is released.