A Distributed Abstract Machine for Safe Ambients

The Ambient calculus [4] is a model for mobile distributed computing. An ambient is the unit of movement. Processes within the same ambient may exchange messages; ambients may be nested, so to form a hierarchical structure. The three primitives for movement allow: an ambient to enter another ambient, n[ in m. P | Q] | m[R] → m[ n[ P | Q] | R]; an ambient to exit another ambient, m[ n[ out m. P | Q] | R] → n[ P | Q] ~ m[R]; a process to dissolve an ambient boundary thus obtaining access to its content, open n. P ~ n[Q] → P | Q.