Actualización de servicios distribuidos con replicación pasiva

[ES] Los servicios distribuidos tendrían que garantizar siempre su disponibilidad. Para conseguir esto se utiliza replicación. Así, cuando una instancia de un componente falle, siempre habrá alguna otra que pueda retomar el servicio interrumpido de una manera transparente para el usuario. Aunque se puedan superar estas situaciones de fallo, la replicación no resuelve todas las situaciones de indisponibilidad de una manera inmediata. Cuando el software ejecutado en un servicio se tenga que actualizar, hay que diseñar algún protocolo para garantizar que la transición entre una versión y la siguiente se haga sin interrumpir la capacidad de servicio. Hoy en día todavía no hay soluciones completas para todos los escenarios. De hecho, todas las entidades que ofrecen servicios distribuidos (bancos, comercios, correo electrónico, mensajería...) llegan a mostrar intervalos de indisponibilidad cuando se hacen estas transiciones. El alumno estudiará algunas soluciones para los casos más sencillos, eligiendo una cuyo diseño mejorará para implantarla y evaluar su rendimiento. La solución asumirá que el servicio utiliza el modelo de replicación pasiva.[EN] Distributed service must always guarantee their availability. Replication is needed for achieving this. Thus, when a component replica fails, there will be others that may resume such an interrupted service in a transparent way. In spite of this, replication does not solve all unavailability situations in a direct way. When the software that is run in a service needs to be upgraded, a protocol needs to be designed in order to guarantee that the transition from the current software version to the next does not endanger service continuity. Nowadays, there are no complete solution for all upgrade scenarios. Indeed, many companies that provide distributed services (banks, commerce, e-mail, instant messaging...) still show unavailability intervals in case of software upgrading. The student should study several solutions for basic cases, selecting one of them in order to improve its design and implement it. Those tasks will be complemented with a performance evaluation. That solution should assume that the implemented service respects the passive replication model.Mendoza Paitán, JE. (2019). Actualización de servicios distribuidos con replicación pasiva. http://hdl.handle.net/10251/130033TFG

Advanced Software Techniques for Data Management Systems. Volume 2: Space Shuttle Flight Executive System: Functional Design

A functional design of software executive system for the space shuttle avionics computer is presented. Three primary functions of the executive are emphasized in the design: task management, I/O management, and configuration management. The executive system organization is based on the applications software and configuration requirements established during the Phase B definition of the Space Shuttle program. Although the primary features of the executive system architecture were derived from Phase B requirements, it was specified for implementation with the IBM 4 Pi EP aerospace computer and is expected to be incorporated into a breadboard data management computer system at NASA Manned Spacecraft Center's Information system division. The executive system was structured for internal operation on the IBM 4 Pi EP system with its external configuration and applications software assumed to the characteristic of the centralized quad-redundant avionics systems defined in Phase B

Advanced data management system analysis techniques study

The state of the art of system analysis is reviewed, emphasizing data management. Analytic, hardware, and software techniques are described