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With recent increasing computational and data requirements of scientific applications, the use of large clustered systems as well as distributed resources is inevitable. Although executing large applications in these environments brings increased performance, the automation of the process becomes more and more challenging. While the use of complex workflow management systems has been a viable solution for this automation process in business oriented environments, the open source engines available for scientific applications lack some functionalities or are too difficult to use for non-specialists. In this work we propose an architectural model for a grid based workflow management platform providing features like an intuitive way to describe workflows, efficient data handling mechanisms and flexible fault tolerance support. Our integrated solution introduces a workflow engine component based on ActiveBPEL extended with additional functionalities and a scheduling component providing efficient mapping between tasks and available resources., Comment: 17th International Conference on Control Systems and Computer Science (CSCS 17), Bucharest, Romania, May 26-29, 2009. Vol. 1, pp. 407-414, ISSN: 2066-4451

17th International Conference on Control Systems and Computer Science (CSCS 17), Bucharest, Romania, May 26-29, 2009. Vol. 1, pp. 401-406, ISSN: 2066-4451.

Grid computing has gained an increasing importance in the last years, especially in the academic environments, offering the possibility to rapidly solve complex scientific problems. The monitoring of the Grid jobs has a vital importance for analyzing the system's performance, for providing the users an appropriate feed-back, and for obtaining historical data which may be used for performance prediction. Several monitoring systems have been developed, with different strategies to collect and store the information. We shall present here a solution based on MonALISA, a distributed service for monitoring, control and global optimization of complex systems, and LISA, a component application of MonALISA which can help in optimizing other applications by means of monitoring services. The advantages of this system are, among others, flexibility, dynamic configuration, high communication performance., Comment: Proc. of the 15th International Conference on Control Systems and Computer Science (CSCS-15), Bucharest, Romania, 2005, pp. 127-130, ISBN: 973-8449-89-8

This paper discusses the latest generation of the MONARC (MOdels of Networked Analysis at Regional Centers) simulation framework, as a design and modelling tool for large scale distributed systems applied to HEP experiments. A process-oriented approach for discrete event simulation is well-suited for describing concurrent running programs, as well as the stochastic arrival patterns that characterize how such systems are used. The simulation engine is based on Threaded Objects (or Active Objects), which offer great flexibility in simulating the complex behavior of distributed data processing programs. The engine provides an appropriate scheduling mechanism for the Active objects with support for interrupts. This approach offers a natural way of describing complex running programs that are data dependent and which concurrently compete for shared resources as well as large numbers of concurrent data transfers on shared resources. The framework provides a complete set of basic components (processing nodes, data servers, network components) together with dynamically loadable decision units (scheduling or data replication modules) for easily building complex Computing Model simulations. Examples of simulating complex data processing systems are presented, and the way the framework is used to compare different decision making algorithms or to optimize the overall Grid architecture and/or the policies that govern the Grid's use., Comment: Buletinul Stiintific al Universitatii "Politehnica" din Timisoara, Romania, Seria Automatica si Calculatoare, Periodica Politechnica, Transactions on Automatic Control and Computer Science Vol.49 (63), 2004, ISSN 1224-600X Special issue on 3rd Edition of RoEduNet International Conference, Timisoara, Romania, 2004

This paper discusses the latest generation of the MONARC (MOdels of Networked Analysis at Regional Centers) simulation framework, as a design and modeling tool for large scale distributed systems applied to HEP experiments. The simulation of Grid architectures has a vital importance in the future deployment of Grid systems for providing the users an appropriate feed-back. We present here an example of simulating complex data processing systems and the way the framework is used to optimize the overall Grid architecture and/or the policies that govern the Grid's use., Comment: in Proc. of 15th International Conference on Control Systems and Computer Science (CSCS-15), pp. 131-135, 2005, Bucharest, Romania, Ed. Politehnica Press, ISBN: 973-8449-89-8

Distributed computing is increasingly being viewed as the next phase of Large Scale Distributed Systems (LSDSs). However, the vision of large scale resource sharing is not yet a reality in many areas - Grid computing is an evolving area of computing, where standards and technology are still being developed to enable this new paradigm. Hence, in this paper we analyze the current development of middleware tools for LSDS, from multiple perspectives: architecture, applications and market research. For each perspective we are interested in relevant technologies used in undergoing projects, existing products or services and useful design issues. In the end, based on this approach, we draw some conclusions regarding the future research directions in this area.

Workflow management systems allow the users to develop complex applications at a higher level, by orchestrating functional components without handling the implementation details. Although a wide range of workflow engines are developed in enterprise environments, the open source engines available for scientific applications lack some functionalities or are too difficult to use for non-specialists. Our purpose is to develop a workflow management platform for distributed systems, that will provide features like an intuitive way to describe workflows, efficient data handling mechanisms and flexible fault tolerance support. We introduce here an architectural model for the workflow platform, based on the ActiveBPEL workflow engine, which we propose to augment with an additional set of components.