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Technical Report HW-MACS-TR-0015
Title | PolyA: True Type Polymorphism for Mobile Ambients |
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Authors | Torben Amtoft, Henning Makholm, J.B. Wells |
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Date | 2004-02-17 |
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Abstract | Previous type systems for mobility calculi (the original Mobile Ambients,
its variants and descendants, e.g., Boxed Ambients and Safe Ambients, and
other related systems) offer little support for generic mobile agents. Previous systems either do not handle communication at all or globally assign fixed communication types to ambient names that do not change as an ambient moves around or interacts with other ambients. This makes it hard
to type examples such as a "messenger" ambient that uses communication
primitives to collect a message of non-predetermined type and deliver it to
a non-predetermined destination.
In contrast, we present our new type system PolyA. Instead of assigning
communication types to ambient names, PolyA assigns a type to each process
P that gives upper bounds on (1) the possible ambient nesting shapes
of any process P0 to which P can evolve, (2) the values that may be communicated at each location, and (3) the capabilities that can be used at each location. Because PolyA can type generic mobile agents, we believe PolyA is the first type system for a mobility calculus that provides type polymorphism comparable in power to polymorphic type systems for the calculus. PolyA is easily extended to ambient calculus variants. A restriction of PolyA has principal typings. |
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Group | ULTRA |
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Notes | |
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