Hypervisors, popularized by Xen and VMware, are quickly becoming commodity. They are appropriate for many usage scenarios, but there are scenarios that require system virtualization with high degrees of both isolation and efficiency. Examples include HPC clusters, the Grid, hosting centers, and PlanetLab. We present an alternative to hypervisors that is better suited to such scenarios. The approach is a synthesis of prior work on resource containers and security containers applied to general-purpose, time-shared operating systems. Examples of such container-based systems include Solaris 10, Virtuozzo for Linux, and Linux-VServer. As a representative instance of container-based systems, this paper describes the design and implementation of Linux-VServer. In addition, it contrasts the architecture of Linux-VServer with current generations of Xen, and shows how Linux-VServer provides comparable support for isolation and superior system efficiency.

High quality software components require a representation that allows the implementation-independent description of the structure and behavior of software components. Hence, the static as well as the dynamic structure of the system has to be represented in a structured way. Graph transformation systems support static and dynamic modeling through a single computational framework for the sake of correctness, maintainability, and integrity. The framework introduced along with the corresponding tool, UPGraDE (Universal Programmed Graph Grammar Development Environment), which is based on the universal graph language GRASP (GRAph grammar with Set Productions). Any type of system can be specified through a minimal set of operations (syntax) and rules to specify the behavior of any type of software (semantics). The UPGraDE Environment, consisting of several totally transparent interconnected modules, performing well defined tasks, is a highly modular and extensible environment suited for nearly every GRASP development purpose.