On the use of code mobility mechanisms in real-time systems

Applications with soft real-time requirements can benefit from code mobility mechanisms, as long as those mechanisms support the timing and Quality of Service requirements of applications. In this paper, a generic model for code mobility mechanisms is presented. The proposed model gives system designers the necessary tools to perform a statistical timing analysis on the execution of the mobility mechanisms that can be used to determine the impact of code mobility in distributed real-time applications

Code offloading on real-time multimedia systems: a framework for handling code mobility and code offloading in a QoS aware environment

Actualmente, os smartphones e outros dispositivos móveis têm vindo a ser dotados com cada vez maior poder computacional, sendo capazes de executar um vasto conjunto de aplicações desde simples programas de para tirar notas até sofisticados programas de navegação. Porém, mesmo com a evolução do seu hardware, os actuais dispositivos móveis ainda não possuem as mesmas capacidades que os computadores de mesa ou portáteis. Uma possível solução para este problema é distribuir a aplicação, executando partes dela no dispositivo local e o resto em outros dispositivos ligados à rede. Adicionalmente, alguns tipos de aplicações como aplicações multimédia, jogos electrónicos ou aplicações de ambiente imersivos possuem requisitos em termos de Qualidade de Serviço, particularmente de tempo real. Ao longo desta tese é proposto um sistema de execução de código remota para sistemas distribuídos com restrições de tempo-real. A arquitectura proposta adapta-se a sistemas que necessitem de executar periodicamente e em paralelo mesmo conjunto de funções com garantias de tempo real, mesmo desconhecendo os tempos de execução das referidas funções. A plataforma proposta foi desenvolvida para sistemas móveis capazes de executar o Sistema Operativo Android.Smartphones and other mobile devices are becoming more powerful and are capable of executing several applications in a concurrent manner. Although the hardware capabilities of mobile devices are increasing in an unprecedented way, they still do not possess the same features and resources of a common desktop or laptop PC. A potential solution for this limitation might be to distribute an application by running some of its parts locally while running the remaining parts on other devices. Additionally, there are several types of applications in domains such as multimedia, gaming or immersive environments that require soft real-time constraints which have to be guaranteed. In this work we are targeting highly dynamic distributed systems with Quality of Service (QoS) constraints, where the traditional models of computation are not sufficient to handle the users’ or applications’ requests. Therefore, new models of computation are needed to overcome the above limitations in order to satisfy the applications’ or users’ requirements. Code offloading techniques allied with resource management seem very promising as each node may use neighbour nodes to request for help in order to perform demanding computations that cannot be done locally. In this demanding context, a full-fledged framework was developed with the objective of integrating code offloading techniques on top of a middleware framework that provides QoS and real-time guarantees to the applications. This paper describes the implementation of the above-mentioned framework in the Android platform as well as a proof-of-concept application to demonstrate the most important concepts of code offloading, QoS and real-time scheduling