Using Interface Inheritance to Address Problems in System Software Evolution

Two specific problems faced in large distributed systems are: (1) evolving and managing different versions of an interface while minimizing the impact on existing clients; and (2) supporting the addition of auxiliary interfaces that are orthogonal to the main interface of an abstraction. In the context of the Spring distributed system, we addressed both problems using an object-oriented interface definition language. Different versions of an interface are represented as different types, with an inheritance relationship that minimizes the impact on existing clients, and allows easy management of versions. We distinguish between fundamental and auxiliary properties, each of which is defined as a separate type. Rather than use simple root inheritance, we use a combination of root and leaf inheritance. This provides flexibility in supporting auxiliary properties, and allows us to add new auxiliary properties as the system evolves, without forcing the system to be recompiled. The solutions have been tested and refined through their use in the Spring system

Using interface inheritance to address problems in system software evolution

El objeto de este artículo se centra en examinar el concepto del derecho fundamental a la propia imagen en España y en Brasil. La Constitución Española de 1978 garantizó el derecho a la propia imagen en el artículo 18.1. La Constitución Brasileña de 1988 incluyó el derecho a la propia imagen en tres incisos del artículo 5°. El objetivo de este texto es explorar, de modo sucinto, la inserción del derecho a la propia imagen en los sistemas constitucionales de España y de Brasil, con el análisis de lo que dice la jurisprudencia del Tribunal Constitucional Español y el Supremo Tribunal Federal de Brasil para depurar si los tres incisos del texto constitucional brasileño corresponden a un concepto tripartito de tal bien jurídico. Se utiliza el método deductivo, con apoyo en una investigación bibliográfica y documental. La principal conclusión es que el concepto adecuado del derecho a la propia imagen consiste en la facultad de aprovechar (positiva) o de excluir (negativa) la posibilidad de la representación gráfica de las expresiones o evocaciones personales visibles del aspecto físico externo que singularizan y tornan recognoscible la figura de la persona humana, concepto éste que puede ser leído en la Constitución Brasileña de 1988. Sin embargo, en España el concepto constitucional del derecho a la propia imagen de la Constitución Española de 1978 se restringe a la facultad negativa (de exclusión). De otro lado, la facultad positiva está reservada al ámbito infraconstitucional. Palabras-clave: Derechos fundamentales. Derecho a la propia imagen. Facultad negativa. Facultad positiva

Using interface inheritance to address problems in system software evolution

Two specific problems faced in large distributed systems are: (1) evolving and managing different versions of an interface while minimizing the impact on existing clients; and (2) supporting the addition of auxiliary interfaces that are orthogonal to the main interface of an abstraction. In the context of the Spring distributed system, we addressed both problems using an object-oriented interface definition language. Different versions of an interface are represented as different types, with an inheritance relationship that minimizes the impact on existing clients, and allows easy management of versions. We distinguish between fundamental and auxiliary properties, each of which is defined as a separate type. Rather than use simple root inheritance, we use a combination of root and leaf inheritance. This provides flexibility in supporting auxiliary properties, and allows us to add new auxiliary properties as the system evolves, without forcing the system to be recompiled

A New Protection Model for Component-Based

Protected operating systems multiplex programs onto resources such that they are isolated from one another — that is, concurrently executing programs cannot interfere with each other. A layer of software known as the kernel provides this protection to the software layers above it. Untrusted, ‘user’ programs are prevented from controlling the protection hardware because they are executed when the processor is in user mode — a mode of reduced privilege. In user mode, instructions that can be used to circumvent protection are unavailable; the processor’s instruction-set is reduced. This thesis introduces a new operating system protection mechanism termed SISR — Software-based Instruction Set Reduction (pronounced scissor). Here, all software (including the kernel) executes in the same processor mode, while both language independence and protection are maintained. Untrusted (that is, ‘user level’) code is prevented from issuing privileged instructions not by reducing the processor’s instruction set, but by scanning code prior to its loading; any code found to contain privileged instructions is not loaded. Memory protection is provided through segmentation. SISR leads to improved architectures (that is, simpler and more modular), and improves performance significantly. Its low overheads make fine-grained protection practical, making it especially well-suited to component-based operating systems. A prototype system has been built for x86-based PCs as a ‘proof-of-concept’. Significant improvements in architectures have been delivered. Tasks that have previously been inextricably linked (such as interrupt handling and CPU scheduling) have been separated into distinct components. Experiments have demonstrated significant improvements in performance, compared even to the leanest research operating systems