Munin is a distributed shared memory (DSM) system that allows shared memory parallel programs to be executed efficiently on distributed memory multiprocessors. Munin is unique among existing DSM systems in its use of multiple consistency protocols and in its use of release consistency. In Munin, shared program variables are annotated with their expected access pattern, and these annotations are then used by the runtime system to choose a consistency protocol best suited to that access pattern. Release consistency allows Munin to mask network latency and reduce the number of messages required to keep memory consistent. Munin's multiprotocol release consistency is implemented in software using a delayed update queue that buffers and merges pending outgoing writes. A sixteen-processor prototype of Munin is currently operational. We evaluate its implementation and describe the execution of two Munin programs that achieve performance within ten percent of message passing implementations of the same programs. Munin achieves this level of performance with only minor annotations to the shared memory programs.

This paper factors out the common denominator underlying these variants: full decoupling of the communicating entities in time, space, and synchronization. We use these three decoupling dimensions to better identify commonalities and divergences with traditional interaction paradigms. The many variations on the theme of publish/subscribe are classified and synthesized. In particular, their respective benefits and shortcomings are discussed both in terms of interfaces and implementations

The deep symmetry of Linear Logic [18] makes it suitable for providing abstract models of computation, free from implementation details which are, by nature, oriented and non symmetrical. I propose here one such model, in the area of Logic Programming, where the basic computational principle is Computation = Proof search.

When distributed systems first appeared, they were programmed in traditional sequential languages, usually with the addition of a few library procedures for sending and receiving messages. As distributed applications became more commonplace and more sophisticated, this ad hoc approach became less satisfactory. Researchers all over the world began designing new programming languages specifically for implementing distributed applications. These languages and their history, their underlying principles, their design, and their use are the subject of this paper. We begin by giving our view of what a distributed system is, illustrating with examples to avoid confusion on this important and controversial point. We then describe the three main characteristics that distinguish distributed programming languages from traditional sequential languages, namely, how they deal with parallelism, communication, and partial failures. Finally, we discuss 15 representative distributed languages to give the flavor of each. These examples include languages based on message passing, rendezvous, remote procedure call, objects, and atomic transactions, as well as functional languages, logic languages, and distributed data structure languages. The paper concludes with a comprehensive bibliography listing over 200 papers on nearly 100 distributed programming languages.

We investigate the issue of designing a kernel programming language for Mobile Computing and describe Klaim, a language that supports a programming paradigm where processes, like data, can be moved from one computing environment to another. The language consists of a core Linda with multiple tuple spaces and of a set of operators for building processes. Klaim naturally supports programming with explicit localities. Localities are first-class data (they can be manipulated like any other data), but the language provides coordination mechanisms to control the interaction protocols among located processes. The formal operational semantics is useful for discussing the design of the language and provides guidelines for implementations. Klaim is equipped with a type system that statically checks access rights violations of mobile agents. Types are used to describe the intentions (read, write, execute, etc.) of processes in relation to the various localities. The type system is used...

Gamma is a minimal language based on local multiset rewriting with an elegant chemical reaction metaphor. The virtues of this paradigm in terms of systematic program construction and design of parallel programs have been argued in previous papers. Gamma can also be seen as a notation for coordinating independent programs in a larger application. In this paper, we study a notion of refinement for programs involving parallel and sequential composition operators, and derive a number of programming laws. The calculus thus obtained is applied in the development of a generic "pipelining" transformation, which enables certain sequential compositions to be refined into parallel compositions. Keywords: Gamma, Multiset Rewriting, Program Transformation. 1 Introduction We first describe the general motivation of the work presented here before summarising the main results developed in the body of the paper. 1.1 Motivation The notion of sequential computation has played a central role in the des...

Scheduling in the context of parallel systems is often thought of in terms of assigning tasks in a program to processors, so as to minimize the makespan. This formulation assumes that the processors are dedicated to the program in question. But when the parallel system is shared by a number of users, this is not necessarily the case. In the context of multiprogrammed parallel machines, scheduling refers to the execution of threads from competing programs. This is an operating system issue, involved with resource allocation, not a program development issue. Scheduling schemes for multiprogrammed parallel systems can be classified as one or two leveled. Single-level scheduling combines the allocation of processing power with the decision of which thread will use it. Two level scheduling decouples the two issues: first, processors are allocated to the job, and then the job's threads are scheduled using this pool of processors. The processors of a parallel system can be shared i...

Abstract. We present PlanetP, a peer-to-peer (P2P) content search and retrieval infrastructure targeting communities wishing to share large sets of text documents. P2P computing is an attractive model for information sharing between ad hoc groups of users because of its low cost of entry and explicit model for resource scaling. As communities grow, however, a key challenge becomes finding relevant information. To address this challenge, our design centers around indexing, content search, and retrieval rather than scalable name-based object location, which has been the focus of recent P2P systems. PlanetP takes the novel approach of replicating the global directory and a compact summary index at every peer using gossiping. PlanetP then leverages this information to approximate a state-of-the-art document ranking algorithm to help users locate relevant information within the large communal data set. Using a prototype implementation together with simulation, we show: (i) it is possible to design a gossiping algorithm that reliably maintains a copy of communal state at each peer yet requires only a modest amount of bandwidth, (ii) our content search and retrieval algorithm tracks the performance of the original ranking algorithm very closely, giving P2P communities a search and retrieval algorithm as good as that possible assuming a centralized server, and (iii) PlanetP’s gossiping and search and retrieval algorithms both scale well to communities of at least several thousand peers. 1

Lime is a system designed to assist in the rapid development of dependable mobile applications over both wired and ad hoc networks. Mobile agents reside on mobile hosts and all communication takes place via transiently shared tuple spaces distributed across the mobile hosts. The decoupled style of computing characterizing the Linda model is extended to the mobile environment. At the application level, both agents and hosts perceive movement as a sudden change of context. The set of tuples accessible by a particular agent residing on a given host is altered transparently in response to changes in the connectivity pattern among the mobile hosts. In this paper we present the key design concepts behind the Lime system. 1 INTRODUCTION Today's users demand ubiquitous network access independent of their physical location. This style of computation, often referred to as mobile computing, is enabled by rapid advances in the wireless communication technology. The networking scenarios enabled ...

. In this paper, we propose ICrafter, a framework for services