Concurrent data access in mobile heterogeneous systems

A mobile computing environment involves accessing information through a wireless network connection. The mobile unit may be stationary, in motion, and/or intermittently connected to a fixed (wired) network. As technology advances are made in software and hardware, the feasibility of accessing information "anytime, anywhere" is becoming a reality. There are similarities involved in accessing information in a multidatabase environment and mobile computing environment. We propose to superimpose a wireless-mobile computing environment on multidatabase system to realize a system capable of effectively accessing a large amount of data over a wireless medium (MDAS-Mobile Data Access System). We show how one can easily map solutions from one environment to another. As a potentially large number of users may simultaneously access the available data, there are several issues involved in the ability to concurrently manage transactions. Current concurrency control schemes do not efficiently manage these accesses because they do not address the limited bandwidth and frequent disconnections associated with wireless networks. This paper proposes a new hierarchical concurrency control algorithm. The proposed concurrency control algorithm uses global locking tables created with semantic information contained within the hierarchy. The performance of the new algorithm is simulated and the results are presented.