EJB, providing specification for development and deployment of component based application, permits distributed development as a central element of J2EE environment that automatically manages transaction management, persistence, and concurrency control, which are the most complicated components in an enterprise environment. In this paper, we aim to resolve DAOs transaction logic complexity and performance reduction of components in the EJB based legacy system. Therefore, this paper describes the design and implementation of IDAO that applies iterator pattern. IDAO achieves an effect that reduces the complexity of transaction logic, system overload by database connection, and reduction of performance through container managed transactions.