Hi Sanoj,
Answer is yes ... RabbitMQ is supported just for smartpos 2.1, (3.0 is 100%web + OSGi) we are about to release SmartPOS version 4 (currenty in testing), it is 100%web & OSGI, but it will support asynchornous scenarios using Cassandra database for data synchronization. stay tunes in twitter : @smartjspnews and for any future questions about smartpos, please use our soruce forge forums.
Regards
Pedro R