Papers by Ian Stokes-Rees
Proceedings of the 5th …, Jan 1, 2004
Control) has been developed by the CERN LHCb physics experiment to facilitate large scale simulat... more Control) has been developed by the CERN LHCb physics experiment to facilitate large scale simulation and user analysis tasks spread across both grid and non-grid computing resources. It consists of a small set of distributed stateless Core Services, which are centrally managed, and Agents which are managed by each computing site. DIRAC utilizes concepts from existing distributed computing models to provide a lightweight, robust, and flexible system. This paper will discuss the architecture, performance, and implementation of the DIRAC system which has recently been used for an intensive physics simulation involving more than forty sites, 90 TB of data, and in excess of one thousand 1 GHz processor-years.
Journal of Grid …, Jan 1, 2009
Carrier-grade networks of the future are currently being standardized and designed under the umbr... more Carrier-grade networks of the future are currently being standardized and designed under the umbrella name of Next Generation Network (NGN). The goal of NGN is to provide a more flexible network infrastructure that supports not just data and voice traffic routing, but also higher level services and interfaces for thirdparty enhancements. Within this paper, opportunities to integrate grid and cloud computing strategies and standards into NGN are considered. The importance of standardized interfaces and interoperability testing demanded by carrier-grade networks are discussed. Finally, a proposal how the testing methods developed at the European Telecommunications Standards Institute (ETSI) can be applied to improve the quality of standards and implementations is presented.
Professional XML schemas
In order to leverage XML's power as a self-describing and extensible language, we need a way... more In order to leverage XML's power as a self-describing and extensible language, we need a way to define and describe the allowable content of any type of XML document. In the past, this has been achieved with DTDs, but these have in many ways fallen short in the requirements ...
Concurrency and …, Jan 1, 2007
The LHCb grid software has been used for two Physics Data Challenges, the most recent of which wi... more The LHCb grid software has been used for two Physics Data Challenges, the most recent of which will have produced 90 TB of data and required over 400 processor-years of computing power. This paper discusses the group's experience with developing Grid Services, interfacing to the LCG, running LHCb experiment software on the grid, and the integration of a number of new technologies into the LHCb grid software. Our experience and utilisation of the following core technologies will be discussed: OGSI, XML-RPC, grid services, LCG middle-ware, and instant messaging.
… and Computers in …, Jan 1, 2010
In this paper we present two parallel Monte Carlo based algorithms for pricing multi-dimensional ... more In this paper we present two parallel Monte Carlo based algorithms for pricing multi-dimensional Bermudan/American options. First approach relies on computation of the optimal exercise boundary while the second relies on classification of continuation and exercise values. We also evaluate the performance of both the algorithms in a desktop grid environment. We show the effectiveness of the proposed approaches in a heterogeneous computing environment, and identify scalability constraints due to the algorithmic structure.
Current grid computing architectures have been based on cluster management and batch queuing syst... more Current grid computing architectures have been based on cluster management and batch queuing systems, extended to a distributed, federated domain. These have shown shortcomings in terms of scalability, stability, and modularity. To address these problems, this dissertation applies architectural styles from the Internet and Web to the domain of generic computational grids. Using the REST style, a flexible model for grid resource interaction is developed which removes the need for any centralised services or specific protocols, thereby allowing a range of implementations and layering of further functionality. The context for resource interaction is a generalisation and formalisation of the Condor ClassAd match-making mechanism. This set theoretic model is described in depth, including the advantages and features which it realises. This RESTful style is also motivated by operational experience with existing grid infrastructures, and the design, operation, and performance of a proto-RESTful grid middleware package named DIRAC. This package was designed to provide for the LHCb particle physics experiment's "off-line" computational infrastructure, and was first exercised during a 6 month data challenge which utilised over 670 years of CPU time and produced 98 TB of data through 300,000 tasks executed at computing centres around the world. The design of DIRAC and performance measures from the data challenge are reported. The main contribution of this work is the development of a REST model for grid resource interaction. In particular, it allows resource templating for scheduling queues which provide a novel distributed and scalable approach to resource scheduling on the grid.
HEP Applications and their Experience with the use of DataGrid Middleware
Journal of Grid …, Jan 1, 2004
S. Burke1, F. Harris2, I. Stokes-Rees2, I. Augustin3, F. Carminati3, J. Closier3, E. van Herwij-n... more S. Burke1, F. Harris2, I. Stokes-Rees2, I. Augustin3, F. Carminati3, J. Closier3, E. van Herwij-nen3, A. Sciaba3, D. Boutigny4, JJ Blaising4, V. Garonne5, A. Tsaregorodtsev5, P. Capiluppi6, A. Fanfani6, C. Grandi6, R. Barbera7, E. Luppi8, G. Negri9, L. Perini9, S. ...
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Papers by Ian Stokes-Rees