Aliasing Models for Mobile Objects
Uwe Nestmann
December 1999 |
Abstract:
In Obliq, a lexically scoped, distributed, object-oriented
programming language, object migration was suggested as the creation of a
copy of an object's state at the target site, followed by turning the object
itself into an alias, also called surrogate, for the remote copy. We
consider the creation of object surrogates as an abstraction of the
above-mentioned style of migration. We introduce Øjeblik, a typed
distribution-free subset of Obliq, and provide four different
configuration-style semantics, which only differ in the respective
aliasing model. We show that two of the semantics, one of which matches
Obliq's implementation, render migration unsafe, while our new proposal
allows for safe migration at least for a large class of program contexts. In
addition, we propose a type system that allows a programmer to statically
guarantee that programs belong to that class. Our work suggests a
straightforward repair of Obliq's aliasing model
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