Supporting Object Migration in Distribution Systems

摘要

To fully support distributed processing in any distributed system, it must be possible to perform remote executions. For maximum benefit, this should also be coupled with the movement of data and programs from sites other than those where the execution is to be performed. Such distributed processing requirements are considered in the context of a Virtual Enterprise which uses an Object-oriented Knowledge Base Managmeent System (OOKBMS) to act not only as a trader, but also the repository for a global model and shared data. Here, the concept of objects causes us to reconsider remote execution and data movement as the more general problem of object migration. In this paper we identify, object migration consisting of the migration of three possible components: object definition, object instances, and object method executables and source. We describe in this paper an exhaustive list of thirteen execution and data location scenarios. The discussion in this paper on object method execution covers not only the migration of executable code between homogeenous systems, but also interpretive code, such as Java, and also compilable programs (source code). Given these considerations, this paper finishes with the definition for a migration protocol using KQML. These performatives provide the mechanisms to support a wide variety of migration plicies and are shown to support the thirteen distributed execution operation scenarios.