Object migration in a heterogeneous world-a multi-dimensional affair

The ability to change the physical location of objects is considered indispensable in today´s highly distributed computing world. As a direct offspring of process migration, object-oriented operating systems now offer object migration as a core mechanism. These systems usually equate migration with a change in physical location. Location is only one attribute whose changes are worth considering. Other attributes evolve as well during the lifetime of an object. Examples include changes in state representation and failure handling semantics. All such attribute changes can be integrated within a generalized object migration model. This results in an N-dimensional space, the object habitat, where object migration is expressed in terms of coordinate changes. This paper introduces the habitat model, and illustrates its application within the COMET heterogeneous distributed computing system. Within COMET, the habitat is a three-dimensional space with location, class and flavor coordinate axes