Advances in wireless networking technology and portable computing devices have led to the emergence of a new computing paradigm known as mobile computing and a number of applications. As a result, software applications have to be redesigned to take advantage of this environment while accommodating the new challenges posed by mobility.
As mobile users wander about, they are bound to encounter a variety of different information sources (databases) that are often autonomous and heterogeneous in nature. Such a collection of autonomous and heterogeneous database is often known as a multidatabase. The existing multidatabase systems do not readily support mobile computing. A new class of multidatabase that provides access to a large collection of data via a wireless networking connection is proposed—a Mobile Data Access System (MDAS). Within the scope of MDAS, a new transaction-processing model is proposed that allows timely and reliable access to heterogeneous and autonomous data sources while coping with the mobility issue. The proposed model extends the existing multidatabase system without any adverse effect to the preexisting local and global users. This is accomplished through the implementation of multi tiered mobile transaction proxies that manage the execution of mobile transactions on behalf of the mobile user. The proposed transaction-processing model is simulated and the results are analyzed.