javac src/pubsub/*.java src/pubsub/interfaces/*.java -d bin
cd bin

start failure detector using command.

rmiregistry 6666 &
java pubsub.FailureDetector -p 6666

start multiple server nodes using command, replace xxxx with a valid port number

rmiregistry xxxx &
java pubsub.EventServer -p xxxx

start client to publish & subscribe, replace xxxx with any server's port number, replace yyyy with an ID of your choice for the client

java pubsub.PubSubClient -p xxxx -d yyyy

Compile project files

javac src/pubsub/*.java src/pubsub/interfaces/*.java -d bin
cd bin

Open a terminal window and start failure detector

rmiregistry 6666 &
java pubsub.FailureDetector -p 6666

Open a terminal window and start server at port 1099

rmiregistry 1099 &
java pubsub.EventServer -p 1099

Open a terminal window and start server at port 1100

rmiregistry 1100 &
java pubsub.EventServer -p 1100

Open a terminal window and start server at port 1101

rmiregistry 1101 &
java pubsub.EventServer -p 1101

Open a terminal window and start client connected to the server listening port 1099

java pubsub.PubSubClient -p 1099 -d 1000

Open a terminal window and start client connected to the server listening port 1101

java pubsub.PubSubClient -p 1101 -d 2000

Start more clients if you want. Run some add topic, add event, subscribe, unsubscribe operations using client's command line prompts
Input "1" in failure detector to check on cluster status
Now quit current leader which should be 1099, and check failure detector and client, things will still run like a charm.