A service acquisition mechanism for server-based heterogeneous distributed systems

摘要

This paper presents a mechanism that facilitates and enhances the use of independently administered remote network servers in the presence of server interface heterogeneity. The mechanism is designed under the client-service model, which extends the client-server model with an abstraction of service to decouple abstract server capabilities from concrete server interface specifics such as server interface binding protocols and the interface operation invocation protocols. The mechanism selects servers, accommodates server interface heterogeneity, and handles server access failures as per the abstract server capabilities desired by the client. It could return the identity of the server used for each service access invocation to facilitate billing, refining service specifications, and reporting server-specific errors. This paper also illustrates a C library interface to this mechanism, and describes a language veneer over the C programming language demonstrating how a typed procedural language could be extended by a few language constructs to support the mechanism under the client-service model. In this language, server capabilities are referenced by abstract data type (ADT) objects, and are accessed by invoking the objects' interface operations using a call-by-value-result paradigm.