Abstract
In recent years there has been considerable interest in developing distributed computing systems. Distribution of computing resources suggests many possible benefits including greater felxibility, enhanced computing power through greater parallelism, and increased reliability.
In practice, achieving any any of these benefits has been difficult, since a distributed system also presents potential problems in naming, synchronization, and the effective use of resources. Consistency problems arise when dealing with operations and data structures that may span machine and device boundaries; that is, should a communications or machine failure occur at an inopportune time, the data may be left in an unknown, incorrect, or inaccessible condition. This type of problem is certainly undesireable in user programs, but special problems arise when operating system data structures become inconsistent. Due to the large number of components involved in a distributed system, these problems are more likely to occur and more damaging in their effects.
Since 1982, the Clouds project has been researching an approach to the construction of a distributed computing environment intended to address these concerns. The Clouds operating system is intended to reliably support effective use of distributed resources. Some of that design is derived from the action/object model of computation developed in Jim Allchin's dissertation.[Allc83] That work suggested an architecture for a distributed, reliable computing system built from abstract data objects and atomic transactions. The architecture, properly implemented, can be used to address many of the problems presented by distributed systems. However, Allchin's work does not address the structure or implementation of the kernel and operating system services necessary for a functional distributed system.
This dissertation explores the requirements for services and structures needed to support a distributed computing environment as suggested by Allchin's work. It contains the design of a distributed operating system kernel which meets these requirements and which could flexibly support various implementations of the Clouds reliable system as well as other forms of object-oriented distributed systems. This dissertation also descibes a prototype implementation, which was done to help refine and validate the design and provide a testbed for further research.
Contents
1. Introduction and Background
2. Kernel Design: Preliminaries
3. The Kernel Interface and Objects
4. Processes, Actions, and Peripherals
5. Functional Flow
6. Prototype Construction and Experience
7. Further Directions
8. Conclusions and Contributions
