Some of my papers on grid computing

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Grid systems and technologies have evolved over nearly a decade; yet, there is still no widely accepted definition for Grids. In particular, the essential attributes that distinguish Grids from other distributed computing environments have not been articulated. Most approaches to definition adopt a static view and consider only the properties and components of, or the applications supported by, Grids. The definition proposed in this paper is based on the runtime semantics of distributed systems. Rather than attempt to simply compare static characteristics of Grids and other distributed computing environments, this paper analyzes operational differences, from the viewpoint of an application executing in both environments. Our definition is expressed formally as an Abstract State Machine that facilitates the analysis of existing Grid systems or the design of new ones with rigor and precision. This new, semantical approach proposes an alternative to the currently accepted models for determining whether or not a distributed system is a Grid.

Keywords: grid computing, distributed computing, formal grid definition, differences between grid and other distributed computing, grid computing model, abstract state machines

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Although, there are attempts to create grid systems, there is no clear definition for grids. In this paper a formal approach is presented for defining elementary functionalities of grid systems. A comparative analysis with conventional distributed systems shows that there are semantical differences not just technical ones. The resulted highly abstract working model for grids can serve as a framework for defining new systems or analysing existing ones.

Keywords: grid computing, distributed computing, grid definition, formal model, differences between grid and other distributed computing, grid computing model, abstract state machines

Ever since the grid was conceptualized, many attempts have been made to reveal the real essence of grid computing. These models have converged towards the notion of virtualization. This paper is aimed at analyzing the semantics of virtualization. It is shown that resource abstraction is necessary for harnessing numerous diverse distributed resources whereas user abstraction is required for realizing resource sharing. Resource and user abstraction together form the cornerstones of virtualization and define a clear separation between grids and other distributed systems.

Keywords: semantics for grid computing, distributed computing, grid definition, formal model, differences between grid and other distributed computing, grid computing model, abstract state machines

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Executing workflows on large-scale heterogeneous distributed computing systems is a challenging task. Albeit, there have been many well elaborated approaches, they are often motivated by a certain class of applications and focus on some implementation specific problems. The work presented in this paper aimed at establishing a highly abstract coordination model for distributed workflow enactment where decentralized control, autonomy, adaptation to high dynamics and partial lack of information are of primary concerns. The model is based on a nature metaphor and envisioned as a chemical reaction where molecules react autonomously according to local and actual conditions. The execution model of such chemical workflow enactment is formalized using the gamma-calculus. In the gamma-calculus control, scheduling, dependencies, errors and the state of the computation are all represented in a single uniform declarative formalism that has a mathematically founded clear semantics. The paper shows that the abstract coordination model expressed in gamma-calculus is able to grasp all aspects of such a chemical enactment, provides a more complex and adaptive framework than most current approaches, and actual realizations may be founded on it.

Keywords: workflow enactment, coordination model, gamma-calculus, nature inspired distributed computing, grid workflow