4,073 research outputs found

    Transparent Dynamic reconfiguration for CORBA

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    Distributed systems with high availability requirements have to support some form of dynamic reconfiguration. This means that they must provide the ability to be maintained or upgraded without being taken off-line. Building a distributed system that allows dynamic reconfiguration is very intrusive to the overall design of the system, and generally requires special skills from both the client and server side application developers. There is an opportunity to provide support for dynamic reconfiguration at the object middleware level of distributed systems, and create a dynamic reconfiguration transparency to application developers. We propose a Dynamic Reconfiguration Service for CORBA that allows the reconfiguration of a running system with maximum transparency for both client and server side developers. We describe the architecture, a prototype implementation, and some preliminary test result

    A Generic Deployment Framework for Grid Computing and Distributed Applications

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    Deployment of distributed applications on large systems, and especially on grid infrastructures, becomes a more and more complex task. Grid users spend a lot of time to prepare, install and configure middleware and application binaries on nodes, and eventually start their applications. The problem is that the deployment process is composed of many heterogeneous tasks that have to be orchestrated in a specific correct order. As a consequence, the automatization of the deployment process is currently very difficult to reach. To address this problem, we propose in this paper a generic deployment framework allowing to automatize the execution of heterogeneous tasks composing the whole deployment process. Our approach is based on a reification as software components of all required deployment mechanisms or existing tools. Grid users only have to describe the configuration to deploy in a simple natural language instead of programming or scripting how the deployment process is executed. As a toy example, this framework is used to deploy CORBA component-based applications and OpenCCM middleware on one thousand nodes of the French Grid5000 infrastructure.Comment: The original publication is available at http://www.springerlink.co

    Platform-independent Dynamic Reconfiguration of Distributed Applications

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    The aim of dynamic reconfiguration is to allow a system to evolve incrementally from one configuration to another at run-time, without restarting it or taking it offline. In recent years, support for transparent dynamic reconfiguration has been added to middleware platforms, shifting the complexity required to enable dynamic reconfiguration to the supporting infrastructure. These approaches to dynamic reconfiguration are mostly platform-specific and depend on particular implementation approaches suitable for particular platforms. In this paper, we propose an approach to dynamic reconfiguration of distributed applications that is suitable for application implemented on top of different platforms. This approach supports a platform-independent view of an application that profits from reconfiguration transparency. In this view, requirements on the ability to reconfigure components are expressed in an abstract manner. These requirements are then satisfied by platform-specific realizations

    The pros and cons of using SDL for creation of distributed services

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    In a competitive market for the creation of complex distributed services, time to market, development cost, maintenance and flexibility are key issues. Optimizing the development process is very much a matter of optimizing the technologies used during service creation. This paper reports on the experience gained in the Service Creation projects SCREEN and TOSCA on use of the language SDL for efficient service creation

    Monitoring extensions for component-based distributed software

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    This paper defines a generic class of monitoring extensions to component-based distributed enterprise software. Introducing a monitoring extension to a legacy application system can be very costly. In this paper, we identify the minimum support for application monitoring within the generic components of a distributed system, necessary for rapid development of new monitoring extensions. Furthermore, this paper offers an approach for design and implementation of monitoring extensions at reduced cost. A framework of basic facilities supporting the monitoring extensions is presented. These facilities handle different aspects critical to the monitoring process, such as ordering of the generated monitoring events, decoupling of the application components from the components of the monitoring extensions, delivery of the monitoring events to multiple consumers, etc.\ud The work presented in this paper is being validated in the prototype of a large distributed system, where a specific monitoring extension is built as a tool for debugging and testing the application behaviour.\u

    Using real options to select stable Middleware-induced software architectures

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    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

    Design of Home Network Architecture using ACE/TAO Real Time Event Service

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    This paper proposes a home network design based on publisher/subscriber architecture which is developed using ACE/TAO Real-time Event Service (RTES) as the middleware platform. This design addresses a feature to support a real-time implementation for home network application such as home automation. Home network participants have been classified into several components based on consumer and supplier implementation in the ACE/TAO RTES in order to simplify the design. To optimize the network utilization, events are filtered based on their type and source for each publisher and subscriber. To deal with heterogeneous type of home appliances, event header information has been extended to wrap more information. Each of events can be configured with a specific scheduling and priority setting to meet its quality of service (QoS) according to the requirement. Network performance in handling an increasing number of consumer or supplier has been evaluated and show an acceptable result. Keywords: Home Network, ACE/TAO, RTES, QoS

    Experiences in Integrated Multi-Domain Service Management

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    Increased competition, complex service provision chains and integrated service offerings require effective techniques for the rapid integration of telecommunications services and management systems over multiple organisational domains. This paper presents some of the results of practical development work in this area, detailing the technologies and standards used, the architectural approach taken and the application of this approach to specific services. This work covers the integration of multimedia services, broadband networks, service management and network management, though the detailed examples given focus specifically on the integration of services and service management
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