Smack is an excellent Java XMPP Library. While creating a pubsub broker in XMPP I faced a strange issue where few messages were missing. I then found a simple way to debug the Smack library. Just start your JVM (java) with the following option: java -Dsmack.debugEnabled=true Class.Name

Ant is a popular, high quality Java based build and deployment tool from Apache Foundation. You can invoke Java programs in ant using the java task. Optionally you may want to pass it command line arguments. Here is how you can do it.