Enterprise applications are increasingly being built using type-safe programming platforms and deployed over horizontally scalable systems. Horizontal scalability depends crucially on the ability to monitor resource usage and to define and enforce resource management policies capable of guaranteeing a desired service level. However, current safe language platforms have very limited support for resource management, and their cluster-enabled versions reflect this deficiency. We describe an architecture of federated Java/spl trade/ virtual machines. Its distinguishing feature is an integrated resource management interface that addresses the above issues. It offers programmatic control over monitoring and controlling the allocation of resources to applications and their components. The scope of each policy can span multiple nodes, realizing finegrained control. New resource types can be defined and integrated into the framework. Remote management of local resources and the notion of cluster-global resources form a powerful combination capable of expressing policies that achieve effective performance isolation for cluster applications.

Software systems in many circumstances need awareness of their resource usage. Meeting performance requirements often requires the ability to manage consumption of resources provided by the environment. Resource management is traditionally handled by operating systems, but the growing need to use safe languages in the systems programming domain adds increased pressure to equip them with resource management capabilities at a level of abstraction that fits gracefully with the language. This paper proposes an extensible, flexible, and widely applicable resource management interface for the Java platform. The interface is small, but capable of modeling a variety of resources and resource management policies. In particular, application-specific resources can be defined, as well as more traditional computational resources such as heap memory and processor time. The interface is presented here in detail, along with a series of examples and a description of a prototype implementation. Copyright © 2004 John Wiley & Sons, Ltd.

This paper describes a novel approach to the treatment of data types in programming languages, which allows a simple interpretation of "polymorphic" or "generic" procedures, makes a simple set of type-checking rules semantically justifiable and provides a straightforward treatment of encapsulation.