Systematic composition of distributed objects: Processes and sessions

We consider a system with the infrastructure for the creation and interconnection of large numbers of distributed persistent objects. This system is exemplified by the Internet: potentially, every appliance and document on the Internet has both persistent state and the ability to interact with large numbers of other appliances and documents on the Internet. This paper elucidates the characteristics of such a system, and proposes the compositional requirements of its corresponding infrastructure. We explore the problems of specifying, composing, reasoning about and implementing applications in such a system. A specific concern of our research is developing the infrastructure to support structuring distributed applications by using sequential, choice and parallel composition, in the anarchic environment where application compositions may be unforeseeable and interactions may be unknown prior to actually occurring. The structuring concepts discussed are relevant to a wide range of distributed applications; our implementation is illustrated with collaborative Java processes interacting over the Internet, but the methodology provided can be applied independent of specific platforms

A protocol reconfiguration and optimization system for MPI

Modern high performance computing (HPC) applications, for example adaptive mesh refinement and multi-physics codes, have dynamic communication characteristics which result in poor performance on current Message Passing Interface (MPI) implementations. The degraded application performance can be attributed to a mismatch between changing application requirements and static communication library functionality. To improve the performance of these applications, MPI libraries should change their protocol functionality in response to changing application requirements, and tailor their functionality to take advantage of hardware capabilities. This dissertation describes Protocol Reconfiguration and Optimization system for MPI (PRO-MPI), a framework for constructing profile-driven reconfigurable MPI libraries; these libraries use past application characteristics (profiles) to dynamically change their functionality to match the changing application requirements. The framework addresses the challenges of designing and implementing the reconfigurable MPI libraries, which include collecting and reasoning about application characteristics to drive the protocol reconfiguration and defining abstractions required for implementing these reconfigurations. Two prototype reconfigurable MPI implementations based on the framework - Open PRO-MPI and Cactus PRO-MPI - are also presented to demonstrate the utility of the framework. To demonstrate the effectiveness of reconfigurable MPI libraries, this dissertation presents experimental results to show the impact of using these libraries on the application performance. The results show that PRO-MPI improves the performance of important HPC applications and benchmarks. They also show that HyperCLaw performance improves by approximately 22% when exact profiles are available, and HyperCLaw performance improves by approximately 18% when only approximate profiles are available

Checkpointing of parallel applications in a Grid environment

The Grid environment is generic, heterogeneous, and dynamic with lots of unreliable resources making it very exposed to failures. The environment is unreliable because it is geographically dispersed involving multiple autonomous administrative domains and it is composed of a large number of components. Examples of failures in the Grid environment can be: application crash, Grid node crash, network failures, and Grid system component failures. These types of failures can affect the execution of parallel/distributed application in the Grid environment and so, protections against these faults are crucial. Therefore, it is essential to develop efficient fault tolerant mechanisms to allow users to successfully execute Grid applications. One of the research challenges in Grid computing is to be able to develop a fault tolerant solution that will ensure Grid applications are executed reliably with minimum overhead incurred. While checkpointing is the most common method to achieve fault tolerance, there is still a lot of work to be done to improve the efficiency of the mechanism. This thesis provides an in-depth description of a novel solution for checkpointing parallel applications executed on a Grid. The checkpointing mechanism implemented allows to checkpoint an application at regions where there is no interprocess communication involved and therefore reducing the checkpointing overhead and checkpoint size

Experimental Results and Evaluation of SmartBox Stimulation Device in a P2P E-learning System

In this paper, we present the experimental results and evaluation of the SmartBox stimulation device in P2P e-learning system which is based on JXTA-Overlay. We also show the design and implementation of the SmartBox environment that is used for stimulating the learners motivation to increase the learning efficiency. The SmartBox is integrated with our P2P system as a useful tool for monitoring and controlling learners¿ activity. We found by experimental results that the SmartBox is an effective way to increase the learner¿s concentration. We also investigated the relation between learner¿s body movement, concentration, and amount of study. From the experimental results, we conclude that the use of SmartBox is an effective way to stimulate the learners in order to continue studying while maintaining the concentration.En aquest article es presenten els resultats experimentals i l'avaluació del dispositiu d'estimulació SmartBox en un sistema d'aprenentatge en línia P2P que es basa en la superposició de JXTA. També es mostra el disseny i implementació de l'ambient de l'SmartBox que s'utilitza per a estimular la motivació dels estudiants per augmentar l'eficiència en l'aprenentatge. L'SmartBox s'integra amb el nostre sistema de P2P com una eina útil per al monitoratge i per controlar l'activitat dels alumnes. Pels resultats experimentals trobem que l'SmartBox és una forma efectiva d'augmentar la concentració de l'alumne. També es va investigar la relació entre el moviment del cos de l'alumne, la concentració i la quantitat d'estudis. Dels resultats experimentals es conclou que l'ús de l'SmartBox és una manera efectiva d'estimular els estudiants per tal que continuïn els seus estudis mentre es manté la seva concentració.En este artículo se presentan los resultados experimentales y la evaluación del dispositivo de estimulación SmartBox en un sistema de aprendizaje en línea P2P que se basa en la superposición de JXTA. También se muestra el diseño e implementación del ambiente del SmartBox que se utiliza para estimular la motivación de los estudiantes para aumentar la eficiencia en el aprendizaje. El SmartBox se integra con nuestro sistema de P2P como una herramienta útil para la monitorización y para controlar la actividad de los alumnos. Por los resultados experimentales encontramos que la SmartBox es una forma efectiva de aumentar la concentración del alumno. También se investigó la relación entre el movimiento del cuerpo del alumno, la concentración y la cantidad de estudios. De los resultados experimentales se concluye que el uso del SmartBox es una manera efectiva de estimular a los estudiantes para que continúen sus estudios mientras se mantiene su concentración

Efficient controlling of end-devices in a JXTA-based P2P platform and its application to online learning

The current Internet infrastructure is becoming each time more heterogeneous regarding computational resources. With the fast improvements in computational capabilities of devices, end-devices are becoming important components for the development of nowadays Internet applications. However, the integration of end-devices into Internet applications is a challenging task due to the intrinsic difficulties of current Internet architecture and protocols as well as computational limitations of end-devices. In this work, we address the issue of the efficient control of end-devices in a JXTA based P2P platform. We take advantage of P2P protocols in order to overcome the limitations of client/server architecture to enable the communication of peer nodes with devices despite of presence of NATs and firewalls. We consider as an end-device the SmartBox that is able to stimulate learners during their learning activity and thus increasing their learning efficiency and outcomes. We evaluate the proposed system by experimental study and show the usefulness of using SmartBox end-device in the development of e-learning applicationsPeer ReviewedPostprint (published version