Recently, there have been several studies focusing on the implementation of process calculi with distribution and mobility. Among these, Pan and GcPan are distributed abstract machines for executing Safe Ambients, a variant of the Ambient calculus. However, in order to use them or to exploit their implementation techniques, we must assume all-to-all and permanent connectivity in the underlying network; this is inappropriate for most real-world wide-area and mobile networks, in which each private network is delimited by network boundaries and each mobile device may become disconnected at any moment. In this paper, we propose novel abstract machines PANmov, GcPANmov, and GcPANshift that can handle such network boundaries and mobile devices by using a special kind of agents called boundary forwarders. Especially in Gc-PAN shift, operations related to boundary forwarders improve the fault tolerance of user programs. Finally, we prove the correctness of the proposed machines by using weak barbed bisimulation.
['Seiji Umatani', 'Masahiro Yasugi', 'Taiichi Yuasa']
Abstract machines for safe ambients in wide-area and mobile networks