830,612 research outputs found
Filtering and scalability in the ECO distributed event model
Event-based communication is useful in many application domains, ranging from small, centralised applications to large, distributed systems. Many different event models have been developed to address the requirements of different application domains. One such model is the ECO model which was designed to support distributed virtual world applications. Like many other event models, ECO has event filtering capabilities meant to improve scalability by decreasing network traffic in a distributed implementation. Our recent work in event-based systems has included building a fully distributed version of the ECO model, including event filtering capabilities. This paper describes the results of our evaluation of filters as a means of achieving increased scalability in the ECO model. The evaluation is empirical and real data gathered from an actual event-based system is used
Safety Evaluation of Critical Applications Distributed on TDMA-Based Networks
Critical embedded systems have to provide a high level of dependability. In
automotive domain, for example, TDMA protocols are largely recommended because
of their deterministic behavior. Nevertheless, under the transient
environmental perturbations, the loss of communication cycles may occur with a
certain probability and, consequently, the system may fail. This paper analyzes
the impact of the transient perturbations (especially due to Electromagnetic
Interferences) on the dependability of systems distributed on TDMA-based
networks. The dependability of such system is modeled as that of
"consecutive-k-out-of-n:F" systems and we provide a efficient way for its
evaluation
Epcast: Controlled Dissemination in Human-based Wireless Networks by means of Epidemic Spreading Models
Epidemics-inspired techniques have received huge attention in recent years
from the distributed systems and networking communities. These algorithms and
protocols rely on probabilistic message replication and redundancy to ensure
reliable communication. Moreover, they have been successfully exploited to
support group communication in distributed systems, broadcasting, multicasting
and information dissemination in fixed and mobile networks. However, in most of
the existing work, the probability of infection is determined heuristically,
without relying on any analytical model. This often leads to unnecessarily high
transmission overheads.
In this paper we show that models of epidemic spreading in complex networks
can be applied to the problem of tuning and controlling the dissemination of
information in wireless ad hoc networks composed of devices carried by
individuals, i.e., human-based networks. The novelty of our idea resides in the
evaluation and exploitation of the structure of the underlying human network
for the automatic tuning of the dissemination process in order to improve the
protocol performance. We evaluate the results using synthetic mobility models
and real human contacts traces
Performance Evaluation of Communication Software Systems for Distributed Computing
In recent years there has been an increasing interest in object-oriented distributed computing since it is better quipped to deal with complex systems while providing extensibility, maintainability, and reusability. At the same time, several new high-speed network technologies have emerged for local and wide area networks. However, the performance of networking software is not improving as fast as the networking hardware and the workstation microprocessors. This paper gives an overview and evaluates the performance of the Common Object Request Broker Architecture (CORBA) standard in a distributed computing environment at NASA Ames Research Center. The environment consists of two testbeds of SGI workstations connected by four networks: Ethernet, FDDI, HiPPI, and ATM. The performance results for three communication software systems are presented, analyzed and compared. These systems are: BSD socket programming interface, IONA's Orbix, an implementation of the CORBA specification, and the PVM message passing library. The results show that high-level communication interfaces, such as CORBA and PVM, can achieve reasonable performance under certain conditions
A Workload Emulator Architecture for Distributed Systems
This report presents the initial design of a general purpose workload emulator that emulates workstations, terminals, and communication equipment attached to host computers and servers in a distributed computing environment. The workload emulator can be programmed to model the time dependent behavior of a workload for performance evaluation of distributed systems
Performance Testing of Distributed Component Architectures
Performance characteristics, such as response time, throughput andscalability, are key quality attributes of distributed applications. Current practice,however, rarely applies systematic techniques to evaluate performance characteristics.We argue that evaluation of performance is particularly crucial in early developmentstages, when important architectural choices are made. At first glance, thiscontradicts the use of testing techniques, which are usually applied towards the endof a project. In this chapter, we assume that many distributed systems are builtwith middleware technologies, such as the Java 2 Enterprise Edition (J2EE) or theCommon Object Request Broker Architecture (CORBA). These provide servicesand facilities whose implementations are available when architectures are defined.We also note that it is the middleware functionality, such as transaction and persistenceservices, remote communication primitives and threading policy primitives,that dominates distributed system performance. Drawing on these observations, thischapter presents a novel approach to performance testing of distributed applications.We propose to derive application-specific test cases from architecture designs so thatthe performance of a distributed application can be tested based on the middlewaresoftware at early stages of a development process. We report empirical results thatsupport the viability of the approach
A Configurable Transport Layer for CAF
The message-driven nature of actors lays a foundation for developing scalable
and distributed software. While the actor itself has been thoroughly modeled,
the message passing layer lacks a common definition. Properties and guarantees
of message exchange often shift with implementations and contexts. This adds
complexity to the development process, limits portability, and removes
transparency from distributed actor systems.
In this work, we examine actor communication, focusing on the implementation
and runtime costs of reliable and ordered delivery. Both guarantees are often
based on TCP for remote messaging, which mixes network transport with the
semantics of messaging. However, the choice of transport may follow different
constraints and is often governed by deployment. As a first step towards
re-architecting actor-to-actor communication, we decouple the messaging
guarantees from the transport protocol. We validate our approach by redesigning
the network stack of the C++ Actor Framework (CAF) so that it allows to combine
an arbitrary transport protocol with additional functions for remote messaging.
An evaluation quantifies the cost of composability and the impact of individual
layers on the entire stack
Evaluating XMPP Communication in IEC 61499-based Distributed Energy Applications
The IEC 61499 reference model provides an international standard developed
specifically for supporting the creation of distributed event-based automation
systems. Functionality is abstracted into function blocks which can be coded
graphically as well as via a text-based method. As one of the design goals was
the ability to support distributed control applications, communication plays a
central role in the IEC 61499 specification. In order to enable the deployment
of functionality to distributed platforms, these platforms need to exchange
data in a variety of protocols. IEC 61499 realizes the support of these
protocols via "Service Interface Function Blocks" (SIFBs). In the context of
smart grids and energy applications, IEC 61499 could play an important role, as
these applications require coordinating several distributed control logics.
Yet, the support of grid-related protocols is a pre-condition for a wide-spread
utilization of IEC 61499. The eXtensible Messaging and Presence Protocol (XMPP)
on the other hand is a well-established protocol for messaging, which has
recently been adopted for smart grid communication. Thus, SIFBs for XMPP
facilitate distributed control applications, which use XMPP for exchanging all
control relevant data, being realized with the help of IEC 61499. This paper
introduces the idea of integrating XMPP into SIFBs, demonstrates the
prototypical implementation in an open source IEC 61499 platform and provides
an evaluation of the feasibility of the result.Comment: 2016 IEEE 21st International Conference on Emerging Technologies and
Factory Automation (ETFA
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