Constraint-based runtime prediction of SLA violations in service orchestrations

Service compositions put together loosely-coupled component services to perform more complex, higher level, or cross-organizational tasks in a platform-independent manner. Quality-of-Service (QoS) properties, such as execution time, availability, or cost, are critical for their usability, and permissible boundaries for their values are defined in Service Level Agreements (SLAs). We propose a method whereby constraints that model SLA conformance and violation are derived at any given point of the execution of a service composition. These constraints are generated using the structure of the composition and properties of the component services, which can be either known or empirically measured. Violation of these constraints means that the corresponding scenario is unfeasible, while satisfaction gives values for the constrained variables (start / end times for activities, or number of loop iterations) which make the scenario possible. These results can be used to perform optimized service matching or trigger preventive adaptation or healing.

VLC oriented energy efficient driver techniques

LEDs are substituting fluorescent and incandescent bulbs as illumination sources due to their low power consumption and long lifetime. Visible Light Communications (VLC) makes use of the LEDs short switching times to transmit information. Although LEDs switching speed is around Mbps range, higher speeds (hundred of Mbps) can be reached by using high bandwidth-efficiency modulation techniques. However, the use of these techniques requires a more complex driver which elevates drastically its power consumption. In this work an energy efficiency analysis of the different VLC modulation techniques and drivers is presented. Besides, the design of new schemes of VLC drivers is described.

Embedded Linux integration using Linuxlink tool and peripheral driver development for Zedboard

This project is divided into two main parts: The first part shows the integration of an Embedded Linux operating system on a development hardware platform named Zedboard. This platform contains a Zynq-7000 System on Chip (Soc) which is composed by two dual core ARM Cortex-A9 processors and a FPGA Artix-7. The Embedded Linux is built with Linuxlink, a Timesys tool. Meanwhile, the platform hardware configuration is done with Xilinx Vivado. The system is loaded with an SD card which requires to have every files needed for the booting process and for the operation. Some of these files are generated with Xilinx SDK software. The second part starts up from the system already built to integrate a peripheral in the Zynq-7000 FPGA. Also the drivers for controlling the peripheral from the operating system are developed. Finally, a user space program is created to test both of them. RESUMEN. Este proyecto consta de dos partes: La primera muestra la integración de un sistema operativo Linux embebido en una plataforma de desarrollo hardware llamada Zedboard. Esta plataforma utiliza un System on Chip (SoC) Zynq-7000 que está formado por dos procesadores ARM Cortex-A9 de doble núcleo y una FPGA Artix-7. El Linux embebido se construye utilizando la herramienta Linuxlink de Timesys, mientras que el hardware de la plataforma de desarrollo se configura con Vivado de Xilinx. El sistema se carga en una tarjeta SD que debe tener todos los archivos necesarios para completar el arranque y hacer funcionar el sistema. Algunos de esos archivos se generan con la herramienta SDK de Xilinx. En la segunda parte se utiliza el sistema construido para integrar un periférico en la FPGA del Zynq-7000, haciendo uso de Vivado, y se desarrollan los drivers necesarios para utilizarlo mediante el sistema operativo. Para probar esta última parte se desarrolla un programa de espacio de usuario.