Carlos Figueira

Implementation of a CORBA-Based Metacomputing System

The access to distributed high performance computing facilities for execution of Java programs has generated considerable interest. A metacomputing system, or metasystem, allows uniform access to heterogeneous resources. Our case study is SUMA, a metasystem defined as a set of corba components, offering services for execution of both sequential and parallel applications. This document describes the most important aspects of suma design in terms of corba services. We present some experimental results related to execution overhead in a campus-wide environment.

Remote data service installation on a grid-enabled Java platform

We define a framework for remote service installation, called SIMG (service installation metaservice on grids). Its main goal is to allow grid users to define and safely install their own data filters on remote data servers. Once installed, these filters may be used like the predefined services and may be available for a broader community of users. SIMG is implemented in SUMA/G, a Globus-enabled platform for remote execution of Java bytecode. We also present our experiences using SIMG for defining and remotely installing two complementary services in a content-based image retrieval system.

Remote class prefetching: improving performance of java applications on grid platforms

In this paper we introduce and evaluate two prefetching techniques to improve the performance of Java applications executed on the grid. These techniques are experimentally evaluated on two grid environments, by running test applications on two different grid deployment configurations. Our testbed is suma/g, a grid platform specifically targeted at executing Java bytecode on Globus grids. The experimental results show that these techniques can be effective on improving the performance of applications run on the grid, especially for compute intensive scientific applications.

Profiling Facility on a Metasystem

A metasystem allows seamless access to a collection of distributed computational resources. We address the problem of obtaining useful information about the performance of applications executed on a metasystem,as well as the performance of the metasystem itself. This article describes the experiences and preliminary results on incorporating a profiling facility in a Java-based metasystem. Our case study is suma, a metasystem for execution of Java bytecode,wit h additional support for scientific computing.

Information and Communication Technologies for social inclusion: Experiences in Venezuela

Information and Communication Technologies (ICT) are recognized as key factors for social and economical development. However, they can also bring about more inequality, creating what is called as digital divide. In this paper we describe the policies implemented in Venezuela since year 2000 in order to develop ICT while reducing digital divide.

Dynamic and Secure Data Access Extensions of Grid Boundaries

Grid technology provides a suitable platform for resource sharing, offering users the possibility of accessing large-scale controlled environments across different organizational boundaries through a virtualized single environment. In order to control accesses to those resources, a unique and global security infrastructure is needed, such as a PKI and Virtual Organizations. Hence, in order to process data in the grid, it must be first uploaded to a suitable resource belonging to the grid. We propose mechanisms to extend the grid data space boundaries by securely integrating data located in the client local file system or in external repositories. The proposed extensions only take place during execution of an application on the grid, preserving privacy and other security properties. We explain their implementation in suma/g , a middleware built on top of Globus, and show some experiment results.

Middleware support for java applications on globus-based grids

In this paper we describe the execution model supported by SUMA/G, a middleware built on top of Globus for execution of Java applications on the grid. This execution model allows a user to launch Java applications that will run on a grid from her machine without requiring this machine to be part of the grid (e.g. a gLite User Interface). Additionally, it allows grid users to regard local file systems, i.e. file systems accessible from their local workstations, as part of the set of file systems accessible within the grid. This eliminates the necessity of performing previous uploads of classes and data files, which helps to meet the grid goal of achieving seamless access to distributed resources. We describe how to implement the services offered by this execution model on Globus-based grids. We compare the use of this execution model with the standard mechanisms for submission of Java jobs in LCG/gLite, a flavor of Globus Toolkit 2. We present experiments showing that this execution model can improve performance for running Java applications on Globus-based grids.

A framework for performance evaluation of parallel applications on the Grid

Performance evaluation of applications running on a Grid is a challenging task. Grid’s resources are heterogeneous in nature, often shared, and dynamic, all of which have important implications on the performance of an application executing on the Grid. For instance, applications performance will suffer from perturbation induced by external load on the network or computational nodes. Also, resources allocated to applications may vary between different executions. In this paper, we propose a simple framework that takes into account these factors to allow users to gain knowledge of fundamental performance characteristics of their parallel applications. This framework was incorporated in SUMA, a Grid-enabled platform for the execution of scientific applications in Java. We show some results of the utilization of this framework, which was tested by analyzing and tuning a parallel application.