Checkpointing distributed applications on mobile computers

The integration of mobile/portable computing devices within existing data networks can be expected to spawn distributed applications that execute on mobile hosts (MHs). For reliability, it is vital that the global state of such applications be checkpointed from time to time. A global checkpoint consists of a set of local checkpoints, one per participant. This paper first identifies the problems in recording a consistent global state of mobile distributed applications. The location of a MH within the static network varies with time and therefore, a MH will first need to be located ("searched") in order to obtain its local checkpoint. Moreover, MHs often (voluntarily) disconnect from the network; a disconnected MH is not reachable from the rest of the network This means that a (disconnected) MH may not be available to provide its local checkpoint. Lastly, a MH is not equipped with stable storage; disk space at a MH is not considered stable due to vulnerability of MHs to loss, theft and physical damage. Therefore, an alternative stable repository is required to save local checkpoints of MHs. This paper presents a checkpointing algorithm for MHs that satisfies these constraints.<
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