C Comparison of Two Distributed Systems: Amoeba and Sprite

This paper compares two distributed operating systems, Amoeba and Sprite. Although the systems share many goals, they diverged on two philosophical grounds: whether to emphasize a distributed computing model or traditional UNIX-style applications, and whether to use a workstation-centered model of computation or a combination of terminals and a shared processor pool. Many of the most prominent features of the systems (both positive and negative) follow from the philosophical differences. For example, Amoeba provides a high-performance user-level IPC mechanism, while Sprite's RPC mechanism is only available for kernel use; Sprite's file access performance benefits from client-level caching, while Amoeba caches files only on servers; and Sprite uses a process migration model to share compute power, while Amoeba uses a centralized server to allocate processors and distribute load automatically

Ontology-based User-defined Rules and Context-aware Service Composition System

Abstract. The World Wide Web is becoming increasingly personalized as users provide more of their information on the Web. Thus, Web service functionality is becoming reliant on user profile information and context in order to provide user-specific data. In this paper, we discuss enhancements to SECE (Sense Everything, Control Everything), a platform for context-aware service composition based on user-defined rules. We have enhanced SECE to interpret ontology descriptions of services. With this enhancement, SECE can now create user-defined rules based on the ontology description of the service and interoperate within any service domain that has an ontology description. Additionally, it can use an ontology-based service discovery system like GloServ as its service discovery back-end in order to issue more complex queries for service discovery and composition. This paper discusses the design and implementation of these improvements

Effective electronic marking for on-line assessment

In response to the demands of increasing student numbers, the BOSS system for submission and assessment has been constructed to enable student programming assignments to be submitted and tested online. More recent developments of this system have been concerned with the addition of electronic marking facilities that incorporate both automated marking, resulting from the automated testing, and manual marking in a secure environment. This paper briefly reviews the system and describes in detail the electronic marksheets, their functionality and their user-interface