Are you using trying Activiti with Cassandra as its main database ? Maybe you have good reasons to do so, but I can´t think of any.
Anyway, I suppose you´re using a JDBC driver for Cassandra. If you _really_, _really_ want to do so, you can achieve that by writing your own JDBC adapter that delegates most of its methods to the original Cassandra driver, but implements a fake setAutoCommit method.
If you want to be fancy, the same goal can be achieved by using AOP.
BTW, did I mention that I think this is a bad idea ? No ? Well, I´ll do it again: don´t do this.
That said, what you CAN do is use Cassandra as a store for historical data produced by your processes. Use listeners or explicit system tasks that pick relevant process instance data (eg: customer Id, product, task, assgnee, etc) and write to a given column family. You can then use a MapReduce tool in order to aggregate this information and publish in a nice dashboard that will make your business users very happy.
BTW: I´ve used this approach in one of my customers. In that particular case, I´ve used WSO2´s BAM (an open source product). This package comes with an embedded Cassandra and Hive components, making it a very good companion for any Activiti-based project.
