Nomad: Towards an Architecture for Mobility in Large Scale Distributed Systems

Abstract

Applets, proxies and increasingly complex web applications point toward the Internet becoming a globally distributed system. Currently these services are provided in an ad hoc fashion at fixed locations, which users locate and access manually. In addition, services are typically provided with little or no regard to the user's location or quality of service requirements. The Nomad architecture developed in this thesis directly addresses these problems and forms the basis of a global infrastructure for mobile object-based distributed system. Applications within the system negotiate and pay for execution resources in order to distribute themselves to meet quality of service requirements. High level support is provided to ease the task of programming mobile applications, reducing the time between prototype and deployment. The major contributions of this thesis are the negotiation and location services. Applications are composed of multiple mobile objects and negotiate for resources using the Vickrey auction protocol. The Nomad negotiation architecture addresses all the shortcomings of the chosen auction protocol, ensuring that within our domain, the protocol makes optimal allocations of execution resources. Supporting the resulting distributed applications is the Nomad location service. The location service architecture transfers responsibility for monitoring the location of an application's mobile objects to the application itself. This has the significant advantage of widely distributing the load incurred when tracking highly mobile objects. These application held fragments of the location service are then integrated into a unified global location architecture.