Adn one more thing which version is more stable with out any bugs jbpm 4.0, 4.1 .4.2 or jbpm 3.2 or please let me know the stable version so that i can start my application
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All versions which are released and not marked otherwise are considered stable. They have passed all tests in the quality assurance matrix. However jBPM 4.x sometimes still lacks some features which exist in jBPM 3.x. For instance the foreach-node is a good example. For information on issues and bugs check JIRA.
If you want to start with jBPM 3.x try 3.2.6.SP1. If you want to use jBPM 4.x grab the freshly released 4.2.