A. A. Khramov, N. A. Anikin
Mobile Data Access System (MDAS) is a multidatabase system (a distributed heterogeneous system) with clients accessing it from a wireless network. Such a system consists of several «local» database management systems (LDBMS) which are loosely coupled and preserve local autonomy, that is, retain full control over their data even after joining the global system. At the same time every MDAS has several features that are unique to the mobile environment. This makes existing methods, which were developed for a multidatabase, inefficient.
This article discusses the problem of concurrency control in such systems. Existing methods are described and a need of developing a new method is shown. We propose a method to ensure global transaction serializability and a transaction management protocol for a MDAS, which includes LDBMS of different types. The only requirement for a LDBMS joining the global system is either to ensure local transaction serializability or to implement Snapshot Isolation. We also discuss the possibilities of applying the results of this research in the field of expert systems.