Soft real-time transactions scheduling in a wireless environment

Over the last decade (approx. 1991), mobile computing technologies have led to increasing demand for processing real time transactions by many current applications. These applications are composed of large distributed databases located on fixed sites and small parts of the database located on mobile hosts (MHs). The MHs and the fixed sites communicate via wireless networks. Mobile users often require timely access to information. We study how to ensure the continuity of soft real time transaction computing despite the disconnection problems that often occur between MHs and fixed sites. We propose a soft real time transaction scheduling protocol, called disconnection tolerance protocol (DT protocol), that efficiently manages the frequent network disconnections. We focus particularly on query transactions. DT protocol is based on an extended transaction scheme where controlled transactions deadline overruns and controlled data imprecision are used.