REPL

Hazelcast requires all class files to be shared between cluster members and clients, due to the nature of the JVM, which is a compiled environment. However, this is often cumbersome, particularly during development, since it requires redeploy of class files and cluster restart.

However, using the -Yrepl-outdir feature of the Scala REPL in combination with the serializers defined in DynamicExecution, we can execute arbitrary code from the REPL to a running Hazelcast cluster.

To enable this, all cluster members (and any clients) must register the dynamic serializers, like this:

serialization.DynamicExecution.register(conf.getSerializationConfig)

Then it's simply a matter of invoking the REPL with -Yrepl-outdir and making sure the directory is on the classpath, something like this:

OUTDIR=$TEMP/hazelcast-scala_repl-classes/$(date +"%s")
mkdir -p $OUTDIR
CP="$OUTDIR:<other jars>"
scala -cp $CP -Yrepl-outdir $OUTDIR