Isabelle Rouvellou - Academia.edu (original) (raw)

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Papers by Isabelle Rouvellou

2013 IEEE 33rd International Conference on Distributed Computing Systems, 2013

IEEE Transactions on Knowledge and Data Engineering, 2011

State monitoring is widely used for detecting critical events and abnormalities of distributed sy... more State monitoring is widely used for detecting critical events and abnormalities of distributed systems. As the scale of such systems grows and the degree of workload consolidation increases in Cloud datacenters, node failures and performance interferences, especially transient ones, become the norm rather than the exception. Hence, distributed state monitoring tasks are often exposed to impaired communication caused by such dynamics on different nodes. Unfortunately, existing distributed state monitoring approaches are often designed under the assumption of always-online distributed monitoring nodes and reliable inter-node communication. As a result, these approaches often produce misleading results which in turn introduce various problems to Cloud users who rely on state monitoring results to perform automatic management tasks such as auto-scaling. This paper introduces a new state monitoring approach that tackles this challenge by exposing and handling communication dynamics such as message delay and loss in Cloud monitoring environments. Our approach delivers two distinct features. First, it quantitatively estimates the accuracy of monitoring results to capture uncertainties introduced by messaging dynamics. This feature helps users to distinguish trustworthy monitoring results from ones heavily deviated from the truth, yet significantly improves monitoring utility compared with simple techniques that invalidate all monitoring results generated with the presence of messaging dynamics. Second, our approach also adapts to non-transient messaging issues by reconfiguring distributed monitoring algorithms to minimize monitoring errors. Our experimental results show that, even under severe message loss and delay, our approach consistently improves monitoring accuracy, and when applied to Cloud application autoscaling, outperforms existing state monitoring techniques in terms of the ability to correctly trigger dynamic provisioning.

Distributed applications composed of collections of Web Services may call for diverse levels of r... more Distributed applications composed of collections of Web Services may call for diverse levels of reliability in different parts of the system. Byzantine fault tolerance (BFT) is a general strategy that has recently been shown to be practical for the development of certain classes of survivable, client–server, distributed applications; however, little research has been done on incorporating it into selective parts of multi-tier, distributed applications like Web Services that have heterogeneous reliability requirements. To understand the impacts of combining BFT and Web Services, we have created Thema, a new BFT middleware system that extends the BFT and Web Services technologies to provide a structured way to build Byzantine-fault-tolerant, survivable Web Services that application developers can use like other Web Services. From a reliability perspective, our enhancements are also novel in that they allow Byzantine-fault-tolerant services: (1) to support the multi-tiered requirements...

The Dependency-Sphere project explores concepts and middleware system support for distributed tra... more The Dependency-Sphere project explores concepts and middleware system support for distributed transaction processing across object and messsaging components. The objective is to enrich standard object middleware and messaging middleware to provide for an increased level of reliability for their use in combination in enterprise systems.

Lecture Notes in Computer Science, 2008

SOAlive aims at providing a community-centric, hosted environment and, in particular, at simplify... more SOAlive aims at providing a community-centric, hosted environment and, in particular, at simplifying the description and discovery of situational enterprise services via a service catalog. We argue that a service community has an impact not only on users and services, but also on the environment itself. Specifically, our position is that a service catalog adds value to users, and is itself enriched, by its incorporation into a community-centric service hosting environment. In addition, analyses of web services directories suggest that a catalog service for enterprise services can be better provided by using a simpler content model that better fits REST, taking advantage of collaborative practices to annotate catalog entries with informal semantic descriptions via tagging, providing a mechanism for embedding invocations of discovered services, and allowing syntactic descriptions to be refined via usage monitoring. The SOAlive service catalog defines a flexible content model, a discovery function that navigates the cloud of tag annotations associated with services in a Web 2.0 fashion, and a service description refinement function that allows the actual use of a service to refine the service description stored in the catalog.

Lecture Notes in Computer Science, 2009

In service-oriented computing, multiple services often exist to perform similar functions. In the... more In service-oriented computing, multiple services often exist to perform similar functions. In these situations, it is essential to have good ways for qualitatively ranking the services. In this paper, we present a new ranking method, ServiceRank, which considers quality of service aspects (such as response time and availability) as well as social perspectives of services (such as how they invoke each other via service composition). With this new ranking method, a service which provides good quality of service and is invoked more frequently by others is more trusted by the community and will be assigned a higher rank. ServiceRank has been implemented on SOAlive, a platform for creating and managing services and situational applications. We present experimental results which show noticeable differences between the quality of service of commonly used mapping services on the Web. We also demonstrate properties of ServiceRank by simulated experiments and analyze its performance on SOAlive.

2010 IEEE International Conference on Web Services, 2010

IEEE Transactions on Software Engineering, 2005

In order to make software components more flexible and reusable, it is desirable to provide busin... more In order to make software components more flexible and reusable, it is desirable to provide business users with facilities to assemble and control them without their needing programming knowledge. This paper describes a fully functional prototype middleware system where variability is externalized so that core applications need not be altered for anticipated changes. In this system, application behavior modification is

SSRN Electronic Journal, 2001

The Dependency-Sphere project explores concepts and middle-ware system support for distributed tr... more The Dependency-Sphere project explores concepts and middle-ware system support for distributed transaction processing across object and messsaging components. The objective is to enrich standard object middleware and messaging middleware to provide for an increased level of reliability for their use in combination in enterprise systems.

Separation of concerns is a fundamental principle of software engineering. Of course, concerns ar... more Separation of concerns is a fundamental principle of software engineering. Of course, concerns are modeled in a variety of guises in contemporary software development, but the modeling approaches used typically depend on the development method, development stage, artifact formalism, and other project-specific factors. Concerns in various representations are also the focus of aspect-oriented software development (AOSD) techniques. However, concerns as such are still not modeled independently, and concernmodeling is still not a distinguished activity in software development. In this chapter we argue that concerns must be first-class entities and concern modeling must be a first-class activity in AOSD. That is, concern modeling should be an explicit and integral part of AOSD methods, and concerns should be modeled in their own appropriate formalisms, separately from their representations in requirements, design, code, and other software artifacts. We discuss the meaning of concern and ...

The Web services platform offers a distributed computing environment where autonomous application... more The Web services platform offers a distributed computing environment where autonomous applications interact using standard Internet technology. In this environment, diverse applications and systems become the components of intraand inter-enterprise integration. Yet, transactional reliability, an often critical requirement on such integration, is presently missing from the Web services platform. In this paper, we address this shortcoming and propose the WSTx framework as an approach to Web service reliability. WSTx introduces transactional attitudes to explicitly describe the otherwise implicit transactional semantics, capabilities, and requirements of individual applications. We show how explicit transactional attitude descriptions can be used by a middleware system to automate the reliable composition of applications into larger Web transactions, while maintaining autonomy of the individual applications.