Hi rams,
If you want to specify a transactionmanager that declare in the spring application context. You could change the <spring-transaction-interceptor> in jbpm.tx.spring.cfg.xml.
<spring-transaction-interceptor transaction-manager="transactionManager"/>
Change the transaction-manager attribute to the real bean name in the xml, and jBPM will use it to find the transactionManager by the name we set.