12,851 research outputs found
Remote Object Detection in Cluster-Based Java
Our work combines Java compilation to native code with a run-time library that executes Java threads in a distributed-memory environment with true parallelism. This approach is implemented within the Hyperion system for the distributed execution of compiled Java programs on clusters of PCs. To provide the illusion of a shared memory to Java threads, Hyperion has been built on top of DSM-PM2, a portable implementation platform for multithreaded distributed-shared-memory protocols. We have designed, implemented and experimented with two alternative consistency protocols compliant with the Java Memory Model. The protocols have different mechanisms for access detection: the first one uses explicit locality checks, whereas the second one is based on page faults. We illustrate the effects of the two access-detection techniques with five applications run on two clusters with different interconnection networks: BIP/Myrinet and SISCI/SCI.Notre travail étudie la compilation de programmes Java vers du code natif, en présence d'une bibliothèque run-time permettant des threads Java de s'exécuter en environnement à mémoire distribuée avec du vrai parallélisme. Pour fournir aux threads Java l'illusion d'une mémoire partagée, notre système de compilation '(appelé Hypérion) a été conçu au-dessus de DSm-PM2, une plateforme portable qui facilite l'implémentation de protocoles de cohérence multi-thread pour des systèmes à mémoire distribuée virtuellement partagée. Nous avons conçu, implémenté et expérimenté deux protocole de cohérence alternatifs, compatibles avec le modèle de mémoire Java (Java Memory Model). Les protocoles utilisent des mécanismes différents pour la détection d'accès aux objets partagés. Nous illustrons les effets des deux techniques de détection d'accès à l'aide de cinq applications exécutées sur deux grappes comportant des réseaux d'interconnexion différents : BIP/Myrinet et SISCI/SC
Using real options to select stable Middleware-induced software architectures
The requirements that force decisions towards building distributed system architectures are usually of a non-functional nature. Scalability, openness, heterogeneity, and fault-tolerance are examples of such non-functional requirements. The current trend is to build distributed systems with middleware, which provide the application developer with primitives for managing the complexity of distribution, system resources, and for realising many of the non-functional requirements. As non-functional requirements evolve, the `coupling' between the middleware and architecture becomes the focal point for understanding the stability of the distributed software system architecture in the face of change. It is hypothesised that the choice of a stable distributed software architecture depends on the choice of the underlying middleware and its flexibility in responding to future changes in non-functional requirements. Drawing on a case study that adequately represents a medium-size component-based distributed architecture, it is reported how a likely future change in scalability could impact the architectural structure of two versions, each induced with a distinct middleware: one with CORBA and the other with J2EE. An option-based model is derived to value the flexibility of the induced-architectures and to guide the selection. The hypothesis is verified to be true for the given change. The paper concludes with some observations that could stimulate future research in the area of relating requirements to software architectures
Parallel and distributed Gr\"obner bases computation in JAS
This paper considers parallel Gr\"obner bases algorithms on distributed
memory parallel computers with multi-core compute nodes. We summarize three
different Gr\"obner bases implementations: shared memory parallel, pure
distributed memory parallel and distributed memory combined with shared memory
parallelism. The last algorithm, called distributed hybrid, uses only one
control communication channel between the master node and the worker nodes and
keeps polynomials in shared memory on a node. The polynomials are transported
asynchronous to the control-flow of the algorithm in a separate distributed
data structure. The implementation is generic and works for all implemented
(exact) fields. We present new performance measurements and discuss the
performance of the algorithms.Comment: 14 pages, 8 tables, 13 figure
Knowledge Discovery in the SCADA Databases Used for the Municipal Power Supply System
This scientific paper delves into the problems related to the develop-ment of
intellectual data analysis system that could support decision making to manage
municipal power supply services. The management problems of mu-nicipal power
supply system have been specified taking into consideration modern tendencies
shown by new technologies that allow for an increase in the energy efficiency.
The analysis findings of the system problems related to the integrated
computer-aided control of the power supply for the city have been given. The
consideration was given to the hierarchy-level management decom-position model.
The objective task targeted at an increase in the energy effi-ciency to
minimize expenditures and energy losses during the generation and
transportation of energy carriers to the Consumer, the optimization of power
consumption at the prescribed level of the reliability of pipelines and
networks and the satisfaction of Consumers has been defined. To optimize the
support of the decision making a new approach to the monitoring of engineering
systems and technological processes related to the energy consumption and
transporta-tion using the technologies of geospatial analysis and Knowledge
Discovery in databases (KDD) has been proposed. The data acquisition for
analytical prob-lems is realized in the wireless heterogeneous medium, which
includes soft-touch VPN segments of ZigBee technology realizing the 6LoWPAN
standard over the IEEE 802.15.4 standard and also the segments of the networks
of cellu-lar communications. JBoss Application Server is used as a server-based
plat-form for the operation of the tools used for the retrieval of data
collected from sensor nodes, PLC and energy consumption record devices. The KDD
tools are developed using Java Enterprise Edition platform and Spring and ORM
Hiber-nate technologies
Software engineering and middleware: a roadmap (Invited talk)
The construction of a large class of distributed systems can be simplified by leveraging middleware, which is layered between network operating systems and application components. Middleware resolves heterogeneity and facilitates communication and coordination of distributed components. Existing middleware products enable software engineers to build systems that are distributed across a local-area network. State-of-the-art middleware research aims to push this boundary towards Internet-scale distribution, adaptive and reconfigurable middleware and middleware for dependable and wireless systems. The challenge for software engineering research is to devise notations, techniques, methods and tools for distributed system construction that systematically build and exploit the capabilities that middleware deliver
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