Valentin Cristea

Publications (69)0 Total impact

• Chapter: Intrusion Detection in Multi-Agent Systems

  Bogdan Ghit, Florin Pop, Valentin Cristea
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  ABSTRACT: This chapter presents an adaptive intrusion detection system for distributed environments dedicated to developing agent-based applications. We propose a scalable, flexible and reactive agent based architecture and a lightweight genetic algorithm that recognizes the intruders in an adaptive and automatic way. Our approach is based on monitoring the level of physical resources usage and implies the detection of those agents that manifest an abusive behavior. We finally enhance Jade with our intrusion detection system and we analyze and illustrate the results obtained in different scenario cases.
  01/1970: pages 235-255;
• Chapter: Monitoring and Performance Analysis of Workflow Applications in Large Scale Distributed Systems

  Dragos Sbirlea, Alina Simion, Florin Pop, Valentin Cristea
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  ABSTRACT: The chapter presents the design, implementation and testing of the monitoring solution created for integration with a workflow execution platform. The monitoring solution is a key for modeling and performance analysis of Grid systems considered as a networking and collaborative systems. The monitoring solution constantly checks the system evolution in order to facilitate performance tuning and improvement. The novelty of the work presented in this chapter is the improvement of distributed application obtained using the real-time information to compute estimates of runtime which are used to improve scheduling. Monitoring is accomplished at application level, by monitoring each job from each workflow and at system level, by aggregating state information from each processing node. The scheduling performance in distributed systems can be improved through better runtime estimation and the error detection can automatically detect several types of errors.
  01/1970: pages 171-191;
• Chapter: Distributed Architectures for Event-Based Systems

  Valentin Cristea, Florin Pop, Ciprian Dobre, Alexandru Costan
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  ABSTRACT: Event-driven distributed systems have two important characteristics, which differentiate them from other system types: the existence of several software or hardware components that run simultaneously on different inter-networked nodes, and the use of events as the main vehicle to organize component intercommunication. Clearly, both attributes influence event-driven distributed architectures, which are discussed in this chapter. We start with presenting the event-driven software architecture, which describes various logical components and their roles in events generation, transmission, processing, and consumption. This is used in early phases of distributed event-driven systems’ development as a blueprint for the whole development process including concept, design, implementation, testing, and maintenance. It also grounds important architectural concepts and highlights the challenges faced by event-driven distributed system developers. The core part of the chapter presents several system architectures, which capture the physical realization of event-driven distributed systems, more specifically the ways logical components are instantiated and placed on real machines. Important characteristics such as performance, efficient use of resources, fault tolerance, security, and others are strongly determined by the adopted system architecture and the technologies behind it. The most important research results are organized along five themes: complex event processing, Event-Driven Service Oriented Architecture (ED-SOA), Grid architecture, Peer-to-Peer (P2P) architecture, and Agent architecture. For each topic, we present previous work, describe the most recent achievements, highlight their advantages and limitations, and indicate future research trends in event-driven distributed system architectures.
  01/1970: pages 11-45;
• Article: Using a Failure History Service for Reliable Grid Node Information

  Catalin Leordeanu, Thomas Ropars, Yvon Jégou, Valentin Cristea, Christine Morin
  Fifth International Conference on P2P, Parallel, Grid, Cloud and Internet Computing.
• Source

  Available from: inrialpes.fr

  Article: FORMAL SPECIFICATION OF CHECKPOINTING ALGORITHMS

  Gavril Godza, Valentin Cristea, Radu Mateescu
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  ABSTRACT: To attain good reliability of any software product, its development should begin with a formal specification. This way, it is very easy to perform correctness verification and some performance evaluation information is also available. Formal specification of distributed systems is frequently used for a cost-effective error detection and correction during the initial phase of the software development process. In order to achieve this goal, several tools have been developed for program analysis, code generation, simulation, testing, test data generation. It is important to notice that this kind of tools and models can be used for general distributed system applications.
• Source

  Available from: Florin Pop

  Article: Prediction based meta-scheduling for grid environments

  Florin Pop, Alexandru Costan, Ciprian Dobre, Valentin Cristea
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  ABSTRACT: This paper presents an approach for the prediction-based optimization of meta-scheduling in Grid environ-ments. Several methods are analyzed for resource state pre-diction to be used in meta-scheduling. Time series predic-tions of the status of distributed systems resources, such as CPU or free memory, are considered in order to improve the system availability. The prediction model is based on actual parameter values and historical information, both provided by the MonALISA monitoring system and its ex-tensions: repository and ApMon. The prediction system ar-chitecture is extensible, in the sense that other monitoring parameters can be easily added and new prediction mod-els can be included. The predictions of Grid resources are used in meta-scheduling for different types of tasks, espe-cially tasks with dependencies that have an associated com-munication cost. The significant improvements obtained for scheduling optimization, with an immediate effect on load balancing and resource utilization are presented.
• Source

  Available from: Florin Pop

  Article: Advance reservation of resources for task execution in grid environments

  Izabela Moise, Diana Moise, Florin Pop, Valentin Cristea
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  ABSTRACT: The paper proposes a solution for the Grid scheduling problem, addressing in particular the requirement of high performance an efficient algorithm must fulfill. Advance Reservation engages a distributed, dynamic, fault-tolerant and efficient strategy which reserves resources for future task execution. The paper presents the main features of the strategy, the functioning mechanism the strategy is based on and the methods used for evaluating the algorithm.
• Source

  Available from: arxiv.org

  Article: An Algorithm for File Transfer Scheduling in Grid Environments

  Alexandra Carpen-Amarie, Mugurel Andreica, Valentin Cristea
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  ABSTRACT: This paper addresses the data transfer scheduling problem for Grid environments, presenting a centralized scheduler developed with dynamic and adaptive features. The algorithm offers a reservation system for user transfer requests that allocates them transfer times and bandwidth, according to the network topology and the constraints the user specified for the requests. This paper presents the projects related to the data transfer field, the design of the framework for which the scheduler was built, the main features of the scheduler, the steps for transfer requests rescheduling and two tests that illustrate the system's behavior for different types of transfer requests.
• Source

  Available from: Florin Pop

  Article: Resource CoAllocation for Scheduling Tasks with Dependencies, in Grid

  Diana Moise, Izabela Moise, Florin Pop, Valentin Cristea
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  ABSTRACT: Scheduling applications on wide-area distributed systems is useful for obtaining quick and reliable results in an efficient manner. Optimized scheduling algorithms are fundamentally important in order to achieve optimized resources utilization. The existing and potential applications include many fields of activity like satellite image processing and medicine. The paper proposes a scheduling algorithm for tasks with dependencies in Grid environments. CoAllocation represents a strategy that provides a schedule for task with dependencies, having as main purpose the efficiency of the schedule, in terms of load balancing and minimum time for the execution of the tasks.