size. This paper presents a scalable and adaptive system-level approach for wireless multimedia in the Proactive Enterprise environment. The fifth paper examines network security. The most common solution available today for cyber security is the hardening of systems via "

Migrating operating system instances across distinct physical hosts is a useful tool for administrators of data centers and clusters: It allows a clean separation between hardware and software, and facilitates fault management, load balancing, and low-level system maintenance. By carrying out

PlanetLab is a global overlay network for developing and accessing broad-coverage network services. Our goal is to grow to 1000 geographically distributed nodes, connected by a diverse collection of links. PlanetLab allows multiple services to run concurrently and continuously, each in its own

to form networked virtual supercomputers or metacomputers. While the physical infrastructure to build such systems is becoming widespread, the heterogeneous and dynamic nature of the metacomputing environment poses new challenges for developers of system software, parallel tools, and applications

of emulation while not giving up the opportunity of running experiments in a large and heterogeneous testbed with realistic network conditions. The work is based on a Linux version of the Dummynet network emulator, largely extended with specific features to improve efficiency on PlanetLab, and to emulate

of emulation while not giving up the opportunity of running experiments in a large and heterogeneous testbed with realistic network conditions. The work is based on a Linux version of the Dummynet network emulator, extended with specific features to improve efficiency on PlanetLab, and with custom

-late. Often there is no feasible method to recharge motes, so energy is a precious resource. Once deployed, a network must be reprogrammable although physically unreachable, and this reprogramming can be a significant energy cost. We present Maté, a tiny communication-centric virtual machine designed

using a self-repairing, softstate based routing layer. This paper presents the Tapestry architecture, algorithms, and implementation. It explores the behavior of a Tapestry deployment on PlanetLab, a global testbed of approximately 100 machines. Experimental results show that Tapestry exhibits stable

This paper considers the support of real-time applications in an

"Grid" computing has emerged as an important new field, distinguished from conventional distributed computing by its focus on large-scale resource sharing, innovative applications, and, in some cases, high-performance orientation. In this article, we define this new field. First, we