José C. Cunha

Grid Computing: Software Environments and Tools

Virtualization in Grids: A Semantical Approach.- Virtualization in Grids: A Semantical Approach.- Using Event Models in Grid Design.- Using Event Models in Grid Design.- Intelligent Grids.- Intelligent Grids.- Programming and Process.- A Grid Software Process.- Grid Programming with Java, RMI, and Skeletons.- User Environments and Tools.- A Review of Grid Portal Technology.- A Framework for Loosely Coupled Applications on Grid Environments.- Toward GRIDLE: A Way to Build Grid Applications Searching Through an Ecosystem of Components.- Programming, Composing, Deploying for the Grid.- ASSIST As a Research Framework for High-Performance Grid Programming Environments.- A Visual Programming Environment for Developing Complex Grid Applications.- Applications.- Solving Computationally Intensive Engineering Problems on the Grid Using Problem Solving Environments.- Design Principles for a Grid-enabled Problem-solving Environment to Be Used by Engineers.- Toward the Utilization of Grid Computing in Electronic Learning.

A graphical development and debugging environment for parallel programs

Abstract To provide high-level graphical support for PVM (Parallel Virtual Machine) based program development, a complex programming environment (GRADE) is being developed. GRADE currently provides tools to construct, execute, debug, monitor and visualize message-passing parallel programs. It offers a high-level graphical programming abstraction mechanism to construct parallel applications by introducing a new graphical language called GRAPNEL. GRADE also provides the programmer with the same graphical user interface during the program design and debugging stages. A distributed debugging engine (DDBG) assists the user in debugging GRAPNEL programs on distributed memory computer architectures. Tape/PVM and PROVE support the performance monitoring and visualization of parallel programs developed in the GRADE environment.

Delta Prolog: A Distributed Backtracking Extension with Events

We present Delta Prolog, a distributed logic programming language that extends Prolog to include AND-parallelism (in a single processor or across a network of processors), interprocess communication via message passing with two-way pattern matching, interprocess synchronization with simultaneous message passing, and distributed backtracking among a family of processes. The extension is achieved, at the language level, by just two additional types of goals — events and splits. The implementation is written part in Prolog and part in C, with a small number of core primitives, to help portability. It is still experimental and expected to evolve. In this work we present the languages distinguishing features, describe its semantics, exhibit programs and analyse their behaviour, examine the implementation, and mention conclusions, advantages of the approach and the next developments.

InStory: a system for mobile information access, storytelling and gaming activities in physical spaces

This paper describes the work carried out in the InStory project. InStory has the goal of defining and implementing a platform for mobile storytelling, information access, and gaming activities. The platform has a flexible computational architecture that integrates heterogeneous devices, different media formats and computational support for different narrative modes and gaming activities. The system is driven and validated by a set of story threads and narratives that are centered on the exploration of physical spaces. This exploration is combined with the perspective of sharing information between users and providing historic context. The project also wants to explore the social aspect of shared narratives and activities, with the idea that the technology can provide new innovative approaches to social participation in different types of events.

An integrated testing and debugging environment for parallel and distributed programs

To achieve a certain degree of confidence that a given program follows its specification, a testing phase must be included in the program development process, and also a complementary debugging phase to help locating the programs bugs. This paper presents an environment which results of the composition and integration of two basic tools: STEPS (Structural TEsting of Parallel Software), which is a testing tool, and DDBG (Distributed DeBuGger), which is a debugging tool. The two tools are presented individually as stand-alone tools, and we describe how they were combined through the use of another intermediate tool: DEIPA (Deterministic re-Execution and Interactive Program Analysis). We claim that the result achieved is a very effective testing and debugging environment.

An experiment in tool integration: the DDBG parallel and distributed debugger

This paper discusses the development of a debugging tool for parallel programs showing how the requirements posed by high-level tools for parallel program development have influenced the design of the debugging system since its early stages of development. We concentrate our attention upon the interfacing of the debugger with other tools of a parallel software engineering environment, namely a graphical programming language and a testing and debugging tool. This is illustrated with the results of our experimentation with the design and implementation of DDBG, a debugger for the PVM environment.

Monte Carlo code for high spatial resolution ocean color simulations

A Monte Carlo code for ocean color simulations has been developed to model in-water radiometric fields of downward and upward irradiance (E(d) and E(u)), and upwelling radiance (L(u)) in a two-dimensional domain with a high spatial resolution. The efficiency of the code has been optimized by applying state-of-the-art computing solutions, while the accuracy of simulation results has been quantified through benchmark with the widely used Hydrolight code for various values of seawater inherent optical properties and different illumination conditions. Considering a seawater single scattering albedo of 0.9, as well as surface waves of 5 m width and 0.5 m height, the study has shown that the number of photons required to quantify uncertainties induced by wave focusing effects on E(d), E(u), and L(u) data products is of the order of 10(6), 10(9), and 10(10), respectively. On this basis, the effects of sea-surface geometries on radiometric quantities have been investigated for different surface gravity waves. Data products from simulated radiometric profiles have finally been analyzed as a function of the deployment speed and sampling frequency of current free-fall systems in view of providing recommendations to improve measurement protocols.

A Framework to support Parallel and Distrubuted Debugging

We discuss debugging prototypes that can easily support new functionalities, depending on the requirements of high-level computational models, and allowing a coherent integration with other tools in a software engineering environment. Concerning the first aspect, we propose a framework that identifies two distinct levels of functionalities that should be supported by a parallel and distributed debugger using: a process and thread-level, and a coordination level concerning sets of processes or threads. An incremental approach is used to effectively develop prototypes that support both functionalities. Concerning the second aspect, we discuss how the interfacing with other tools has influenced the design of a process-level debugging interface (PDBG) and a distributed monitoring and control layer called (DAMS).

An integrated course on parallel and distributed processing

Most known teaching experiences focus on parallel computing courses only, but some teaching experiences on distributed computing courses have also been reported. In this paper we describe a course on Parallel and Distributed Processing that is taught at undergraduate level in the Computer Science degree of our University.This course presents an integrated approach concerning concurrency, parallelism, and distribution issues. Its a breadth-first course addressing a wide spectrum of abstractions: the theoretical component focus on the fundamental abstractions to model concurrent systems, including process cooperation schemes, concurrent programming models, data and control distribution, concurrency control and recovery in transactional systems, and parallel processing models; the practical component illustrates the design and implementation issues involved in selected topics such as a data and control distribution problem, a distributed transaction-based support system and a parallel algorithm.We also discuss how this approach has been contributing to prepare the student to further actions regarding research and development of concurrent, distributed, or parallel systems.

Pattern operators for grid environments

A pattern based approach for developing applications in a Grid computing environment is presented, and is based on the ability to manage components and their interactions. The approach provides a formal way of combining recurrent themes in Grid applications, and provides a set of operators that may be used to manipulate the patterns. The operators may be applied to individual patterns or groups, and may be managed as an independent library. The patterns distinguish between service providers and users, and may be used to also analyse the properties of a collection of components, or to vary these properties subject to a set of predefined constraints. Patterns are expressed in the Unified Modelling Language (UML), and operators correspond to manipulation of components within each pattern.