pekko-akka-compat

Some test scenarios to try out Pekko and Akka remote actors together. apache/pekko#146 is open to look at facilitating this.

See https://cwiki.apache.org/confluence/display/PEKKO/Pekko+Akka+Compatibility

PekkoAkkaNoInterop

• Starts Akka and Pekko remote actors and it shows that Akka and Pekko can communicate between actors of the same type. We know they will not interoperate yet.
• So far, the key thing is that you can already have Akka and Pekko code running in the same JVM.

PekkoToAkkaInterop

• relies on a patched pekko-remote jar in lib dir - that includes the changes in apache/pekko#108
• In this test, the PekkoLocalActor2 sends a message to the AkkaRemoteActor
• Pekko has been configured using application2.conf to use akka URIs so Akka accepts the message. Pekko also needs to accept akka messages so that it can handle the response.
• The Akka team are very unlikely to make an equivalent change that lets Akka use or accept pekko URIs

PekkoToAkkaAeronInterop

• basically, the same as PekkoToAkkaInterop but uses Artery comms instead of Classic (Netty) comms

PekkoAkkaAeronCluster

• tries to start an Akka cluster with seed nodes and then to get a Pekko node to join it
• uses the settings to get pekko to use and accept akka URIs
• fails though - it seems like the Akka nodes try to verify the Pekko node and the data that the Pekko node provides includes HOCON data that has pekko prefixed configs while Akka expects the configs to have an akka prefix - see akka.cluster.JoinConfigCompatCheckCluster