Events injected by publishers into a publish/subscribe system may reach users through a variety of devices: a stationary desktop, a laptop, a mobile phone, etc. We argue that the "last hop" -- from the network to the output device -- has unique properties, owing to the mobile nature of these devices, and as such demands special consideration. In particular, user's preferences and location may limit ...

Transactional middleware platforms must accommodate an increasingly diverse range of requirements from both applications and the underlying systems. It is clear that applications have characteristics and requirements that vary a lot, and that transactional middleware must be able to support the potential variety in transaction execution requirements. In this paper we describe ReflecTS, a reflective ...

In this position paper, we focus on issues related to middleware support for software mobility in ad hoc and pervasive systems. In particular, we are interested in moving the computational environment of a mobile user following his trajectory. We present details of WAIFARER, a prototype implementation that automatically saves and restores application level state to support this mobility. Security, ...

This exstended abstract presents an asymmetric and programmable (extensible) approach to pervasive computing. The idea is to off-load computations from light portable clients into a back-bone of seamlessly integrated servers. This way, a user can extend and personalize his pervasive computational environment by installing computations following his trajectory throughout the day. Focus on this extended ...

The performance of the collective operations provided by a communication library is important for many applications run on clusters. The communication structure of collective operations can be organized as a tree. Performance can be improved by configuring and mapping the tree to the clusters in use. We describe and demonstrate an approach for evaluating the performance of different configurations ...

This paper proposes an external sorting algorithm for large data as an alternative to the widely used merge-sort algorithm. The algorithm we present is an application of the widely known quick-sort algorithm to large sequences of data stored externally on a disk device. The problem with the merge-sort algorithm is not its time complexity but the large amount of time it requires to output its first ...

A large class of linear recursive queries compute the bill-of-materials of database relations.This paper presents a novel algorithm that computes the bill-of-materials of its argument's (database) relation. The algorithm uses a special join operation that accumulates the cost of composite parts, without constructing the transitive closure of the argument relation, thus saving time and space. We ...

We have developed EventSpace, a configurable data collecting, management and observation system for monitoring low-level synchronization and communication events with the purpose of understanding the behavior of parallel applications on clusters and multi-clusters. Applications are instrumented by adding data collecting code in the form of event collectors to an applications communication paths. ...

Pesto aims at providing highly available and secure storage for longlived data to mobile users roaming into untrusted environments. Security in Pesto encompasses the following three aspects: availability, safety, and privacy. A mechanism supporting one aspect may adversely affect another. For example, replication may increase availability but complicates supporting confidentiality, and simply ...

The Pesto distributed storage platform is geared towards a computing model where private machines play a pivotal r ˆ ole. We argue that no centralized solutions are acceptable in its design and that it supports allocation of separate tasks to separate system components found in its target environment. Hence, Pesto separates trust from responsibility, storage from access control policy, and ...