A highly productive platform accelerates the production of research results. The design of a Virtual Machine (VM) written in the Java™ programming language can be simplified through exploitation of interfaces, type and memory safety, automated memory management (garbage collection), exception handling, and reflection. Moreover, modern Java IDEs offer time-saving features such as refactoring, auto-completion, and code navigation. Finally, Java annotations enable compiler extensions for low-level “systems programming” while retaining IDE compatibility. These techniques collectively make complex system software more “approachable” than has been typical in the past. The Maxine VM, a metacircular Java VM implementation, has aggressively used these features since its inception. A co-designed companion tool, the Maxine Inspector, offers integrated debugging and visualization of all aspects of the VM's runtime state. The Inspector's implementation exploits advanced Java language features, embodies intimate knowledge of the VM's design, and even reuses a significant amount of VM code directly. These characteristics make Maxine a highly approachable VM research platform and a productive basis for research and teaching.

The Java™ 2 Platform, Enterprise Edition (J2EE™), is established as the standard platform for hosting enterprise applications written in the Java programming language. Similar to an operating system, a J2EE server can host multiple applications, but this is problematic due to limitations on scalability, weak inter-application isolation and inadequate resource management facilities in the underlying Java platform. These limitations lead to a proliferation of server instances with a consequent dramatic increase in the total memory footprint and more complex system administration. The Multi-tasking Virtual Machine (MVM) solves this problem by providing an efficient and scalable implementation of the isolate API for multiple, isolated tasks, enabling the co-location of multiple server instances in a single MVM process. Isolates also enable the restructuring of a J2EE server implementation as a collection of isolated components, offering increased flexibility and reliability. The resulting system is a step towards a complete and scalable operating environment for enterprise applications. Copyright © 2006 John Wiley & Sons, Ltd.

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.

This paper presents an overview of the programming language Modula-3, and a more detailed description of its type system.

Abstract The essential components of an effective program development environment are described. These assist in the interactive investigation of program behaviour and accelerate the rate at which programs are modified. The whole system is compact and simple, being designed for use on small machines. It is considered as important to understand how to use these tools as it is to provide them.

Abstract A list processor, SLP, is presented as a means for manipulating data structures represented as compact lists. The list space is both paged and segmented in order to handle large data structures on a conventional minicomputer. The list processing primitives arc provided as procedure calls embedded in a high‐level language, and the system includes aids for developing user programs. The implementation for a PDP 11/45 computer is presented along with a discussion of the use and performance of the system in practice.