Here are my requirements,
1. I want to use free package
2. I don't know the traffic requirements yet on my application
3. I want to have it relatively simple in terms of dependency jar files etc
4. I don't want gigantic messaging system which is meant for big organizations
5. I want a system which has some monitoring interface inbuilt or available by another tools for the system
Please feel free to ask more questions if you have for me.