Causal ordering in distributed mobile systems

There is a growing trend towards using mobile computing environment for several applications, and it is important that the mobile systems are given adequate support both at the systems level and at the communication level. Causal ordering is a useful property, particularly in applications that involve human interactions. (Such applications are common in mobile computing environments.) In this paper, we present three algorithms for causal ordering in mobile systems. The first algorithm handles the resource constraints of the mobile hosts, but the system is not easily scalable with respect to the number of mobile hosts and is not graceful to host disconnections and connections. Our second algorithm eliminates the above disadvantages at the cost of inhibiting some messages. The third algorithm is a combination of the first two algorithms.