Abstract Split execution is a common model for providing afriendly environment on a foreign machine. In this model, a remotely executing process sends some or all of its systemcalls back to a home environment for execution. Unfortunately, hand-coding split execution systems for experimen-tation and research is difficult and error-prone. We have built a tool, Bypass, for quickly producing portable and cor-rect split execution systems for unmodified legacy applications. We demonstrate Bypass by using it to transparentlyconnect a POSIX application to a simple data staging system based on the Globus toolkit. 1.

be minimized by deploying a kernel agent called a packet filter, which discards unwanted packets as early as possible. The original Unix packet filter was designed around a stack-based filter evaluator that performs sub-optimally on current RISC CPUs. The BSD Packet Filter (BPF) uses a new, registerbased

In a recent Physical Review Letters paper, Vicsek et. al. propose a simple but compelling discrete-time model of n autonomous agents fi.e., points or particlesg all moving in the plane with the same speed but with dierent headings. Each agent's heading is updated using a local rule based

-measurement of these issues are subject to attacks that are able to exploit the vulnerabilities of the operating system kernel (OS kernel). To protect agents and agencies against such risks, we proposed a novel approach that isolates the OS kernel and limit modifications to the agency system in the physical memory space. Our

VM called a virtual appliance. Because of the semantics gap in Hardware Abstraction Layer (HAL)-based virtualization, a physical machine’s virtual appliance requires the support of per-VM in-guest agents to perform VM-specific operations such as kernel data structure access and modification

The U-Net communication architecture provides processes with a virtual view of a network interface to enable userlevel access to high-speed communication devices. The architecture, implemented on standard workstations using offthe-shelf ATM communication hardware, removes the kernel from

, clear separation between mechanism and policy, and extensibility. To achieve these ends, Bro is divided into an “event engine” that reduces a kernel-filtered network traffic stream into a series of higher-level events, and a “policy script interpreter” that interprets event handlers written in a

(or other agent external to the protection system) making a request.

Since 1984, the Condor project has enabled ordinary users to do extraordinary computing. Today, the project continues to explore the social and technical problems of cooperative computing on scales ranging from the desktop to the world-wide computational grid. In this chapter, we provide the history and philosophy of the Condor project and describe how it has interacted with other projects and evolved along with the field of distributed computing. We outline the core components of the Condor system and describe how the technology of computing must correspond to social structures. Throughout, we reflect on the lessons of experience and chart the course traveled by research ideas as they grow into production systems.

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