Transmitting Abstract Values in Messages

摘要

This thesis develops primitives for a programming language intended for use in a distributed computer system where individual nodes may have different hardware or software configurations. Our primitives are presented as extensions to the CLU language. We assume that differences in hardware and in administrative policy require that individual nodes be free to choose their own local representations for common types, including user-defined types. Our main objective is to provide primitives to communicate values of user-defined type. Our primitives support a large degree of node autonomy, without requiring that communicating nodes have prior knowledge of one another's special characteristics. We argue that the precise meaning of value transmission is type-dependent; thus the user, not the language, must control the meaning of transmission for values of a type. (Author)