A component-based middleware framework for configurable and reconfigurable Grid computing

Significant progress has been made in the design and development of Grid middleware which, in its present form, is founded on Web services technologies. However, we argue that present-day Grid middleware is severely limited in supporting projected next-generation applications which will involve pervasive and heterogeneous networked infrastructures, and advanced services such as collaborative distributed visualization. In this paper we discuss a new Grid middleware framework that features (i) support for advanced network services based on the novel concept of pluggable overlay networks, (ii) an architectural framework for constructing bespoke Grid middleware platforms in terms of 'middleware domains' such as extensible interaction types and resource discovery. We believe that such features will become increasingly essential with the emergence of next-generation e-Science applications. Copyright (c) 2005 John Wiley & Sons, Ltd

Diffusion as mixing mechanism in granular materials

We present several numerical results on granular mixtures. In particular, we examine the efficiency of diffusion as a mixing mechanism in these systems. The collisions are inelastic and to compensate the energy loss, we thermalize the grains by adding a random force. Starting with a segregated system, we show that uniform agitation (heating) leads to a uniform mixture of grains of different sizes. We define a characteristic mixing time, $\tau_{mix}$, and study theoretically and numerically its dependence on other parameters like the density. We examine a model for bidisperse systems for which we can calculate some physical quantities. We also examine the effect of a temperature gradient and demonstrate the appearance of an expected segregation.Comment: 15 eps figures, include

Preliminary Specification of Basic Services and Protocols

The objective of D5 is to provide a preliminary definition of basic services and protocols that will be necessary to program CORTEX applications made of sentient objects. Furthermore, the aim of D5 is also to provide an architectural view of the possible composition of services and relations among them. In this view, some services are intended to facilitate communication with certain required properties, others are fundamentally event-oriented services, providing extra functionality at a middleware level and, finally, the remaining services are essentially supporting services, which can be used by event and communication services, as well as directly by applications. More specifically, in terms of event and communication services the deliverable describes a content and cell based predictive routing protocol to provide predictability in mobile ad hoc environments as envisaged in CORTEX, it specifies the messages used by the TBMAC protocol and studies the inaccessibility of the latter, it specifies an event service that implements anonymous communication based on the publish-subscribe paradigm, it describes the deployment of event-channels on a CAN-bus network and, finally, it provides a preliminary specification of the interface of an adaptable timed event service (ATES). In terms of supporting services, the deliverable describes protocols for the implementation of all the basic services defined within the Timely Computing Base (TCB) and provides a specification of resource management services defined accordingly to a resource and task mode

Multilevel modelling software development

Different from other engineering areas, the level of reuse in software engineering is very low. Also, developing large-scale applications which involve thousands of software elements such as classes and thousands of interactions among them is a complex and error-prone task. Industry currently lacks modelling practices and modelling tool support to tackle these issues. Model driven development (MDD) has emerged as an approach to diminishing software development complexity. We claim that models alone are not enough to tackle low reuse and complexity. Our contribution is a multilevel modelling development (MMD) framework whereby models are defined at different abstraction levels. A modelling level is constructed out by assembling software elements defined at the adjacent lower-level. MMD effectively diminish development complexity and facilitates large-scale reuse. Zapotitlán 2006 IEEE

Reconfiguration of Resources in Middleware

The monolithic and inflexible nature of current middleware has made it difficult to deal with emerging technologies such as multimedia. We believe that reflection provides a principled means to achieve the flexibility and adaptation required. The main focus of this paper regards the reconfiguration of resources in middleware within the context of OpenORB, a reflective middleware architecture. A resource model is presented which provides a representation of the physical resources whereby various levels of abstraction are offered. The approach is validated by a series of experimental results. 1

QoS management specification support for multimedia middleware

Middleware technologies are now widely used in order to provide support for the interaction of systems relying on different hardware and operating systems. At present middleware platforms, however, do not provide enough support for both the configuration and reconfiguration of quality of service (QoS) management aspects of real-time applications such as distributed multimedia systems. That is, current middleware only provides support for the low-level specification of QoS properties. This paper presents an architecture description language (ADL) called Xelha for the high-level specification of QoS management in multimedia middleware whereas lower-level aspects can be tuned by using an aspect-oriented suite of languages referred to as resource configuration description language (RCDL). Tool support is also provided for the interpretation of the Xelha and RCDL languages

Adaptive resource management in middleware:a survey

Current middleware technologies cannot meet the demands of new application areas, such as embedded and mobile systems, that require mechanisms for dealing with a changing environment. This article reviews several approaches for providing adaptive resource management for middleware. Current middleware technologies, such as the Common Object Request Broker Architecture (CORBA) and .NET (http://msdn.microsoft.com/net), mask system and network heterogeneity problems and alleviate the inherent complexity of distributed systems in many application areas. However, the recent emergence of new application areas for middleware, such as embedded systems, real-time systems, and multimedia, imposes challenges that few existing middleware platforms can meet. In particular, because they impose greater resource-sharing and dynamism demands, these application areas require more complex and sophisticated middleware. Resource sharing must be controlled and predictable to ensure that activities running on the same middleware instance have adequate resources

Towards a software product line-based approach to adapt IaaS cloud configurations

International audienceCloud computing is nowadays one of the most promising IT technologies, since it provides seemingly unlimited resources on demand at low costs. Hence, different types of applications have been migrated to IaaS environments, e.g. multi-tier (distributed) applications. However, in order to benefit from such characteristics, cloud configurations (i.e. virtual resource configurations) should be designed accordingly to the necessities of the applications. Furthermore, such configurations have to provide the required resources not only at the application deployment-time, but also during the whole application execution time. Hence, adaptive paradigms are required when designing solutions to cloud applications with dynamic resource requirements. Software Product Lines (SPLs) provide great flexibility and a high level of abstraction to describe complete system configurations. Even though SPLs are not commonly used to describe changes after an initial product (configuration) has been created, their inherent characteristics can enable producing the required virtual resource configuration to adapt applications after their initial deployment, i.e., at runtime. In this paper, we present an approach to create and adapt cloud configurations at the IaaS level by using SPLs. We focus on the architectural design of our solution as well as on the possible implementation challenges we could face

An RLS Memory-based Mechanism for the Automatic Adaptation of VMs on Cloud Environments

International audienceOne key factor for Cloud computing success is the resource flexibility it provides. Because of this characteristic, academia and industry have focused their efforts on making efficient use of cloud computational resources without having to sacrifice performance. One way to achieve this purpose is through the automatic adaptation of the computational capabilities of VMs according to their resource utilization and performance. In this paper we present the design and preliminary results of our resource adaptation solution, which proactively adapts VMs (memory-based vertical scaling) to maintain an expected performance. Our solution targets multi-tier applications deployed on Cloud environments, and its core resides in RLS-based resource and performance predictors. Our results show that our solution, when compared with VMs with larger and permanently allocated computational resources, is able to maintain expected performance while reducing resource waste