Solving the Linda multiple rd problem using the copy-collect primitive

AbstractLinda is a mature co-ordination language that has been in use for several years. However, as a result of recent work on the model we have found a simple class of operation that is widely used in many different algorithms which the Linda model is unable to express in a viable fashion. An example algorithm which uses this operation is the composition of two binary relations. By examining how to implement this in parallel using Linda we demonstrate that the approaches possible using the current Linda primitives are unsatisfactory. This paper demonstrates how this “multiple rd problem” can be overcome by the addition of a primitive to the Linda model, copy-collect. This builds on previous work on another primitive called collect (Butcher et al., 1994). The parallel composition of two binary relations using the copy-collect primitive can be achieved with maximal parallelism

Orchestrating Tuple-based Languages

The World Wide Web can be thought of as a global computing architecture supporting the deployment of distributed networked applications. Currently, such applications can be programmed by resorting mainly to two distinct paradigms: one devised for orchestrating distributed services, and the other designed for coordinating distributed (possibly mobile) agents. In this paper, the issue of designing a pro- gramming language aiming at reconciling orchestration and coordination is investigated. Taking as starting point the orchestration calculus Orc and the tuple-based coordination language Klaim, a new formalism is introduced combining concepts and primitives of the original calculi. To demonstrate feasibility and effectiveness of the proposed approach, a prototype implementation of the new formalism is described and it is then used to tackle a case study dealing with a simplified but realistic electronic marketplace, where a number of on-line stores allow client applications to access information about their goods and to place orders

Analysis of Peer-to-Peer protocolsperformance for establishing a decentralized desktop Grid middleware

International audienceThe Desktop Grid technology consists mainly in exploiting personal computer, geographically dispersed, to deliver massive compute power to investigate complex and demanding problems in a variety of different scientific fields. However, as resources number increases, the need for scalability and decentralization becomes more and more essential. Since such properties are exhibited by Peer-to-Peer systems, we aim at using them to create a decentralized desktop grid middleware. Nevertheless, in order to judge the efficiency of such P2P library, an experimental performance evaluation of the provided functionalities is unavoidable. Very few analysis of this kind have been reported, as most evaluations are limited to complexity analysis and to simulations. Such experimental analysis are important, especially when using P2P tools in grid computing context, when applications may have precise efficiency requirement. In this paper, we focus on three libraries: Bonjour, Avahi and Pastry, which provide generic API intended to serve as basis for specialized P2P applications. We perform a performance evaluation of the scalability and their capacity to register and browse an important number of services over 300 hosts in Grid'5000 for recent versions of Pastry, Avahi and Bonjour. We provide detailed analysis explaining the behavior of each library related to two criteria: the elapsed time for registration services and the needed time to discover services. Our aim is to choose the most adequate protocol for creating a decentralized middleware for desktop grid