Roberto Beraldi

Learn More
The completely decoupled interaction model offered by the publish/subscribe communication paradigm perfectly suits the interoperability needs of todays large-scale, dynamic, peer-to-peer applications. The unmanaged environments, where these applications are expected to work, pose a series of problems (potentially wide number of partipants, low-reliability(More)
Recently many scalable and efficient solutions for event dissemination in publish/subscribe (pub/sub) systems have appeared in the literature. This dissemination is usually done over an overlay network of brokers and its cost can be measured as the number of messages sent over the overlay to allow the event to reach all intended subscribers. Efficient(More)
An in-depth review of service discovery protocols (SDPs) in multihop mobile ad hoc networks analyzes SDP building blocks and determines SDP suitability based on architecture, mobility, and network size. Mobile ad hoc networks (manets) include a variety of devices, such as cell phones, PDAs, laptops, and other relatively larger devices. These devices can(More)
Point-to-point transmissions represent a fundamental primitive in any communication network. Despite many proposals have appeared in the literature, providing an efficient implementation of such an abstraction in mobile ad hoc networks still remains an open issue. This paper proposes a probabilistic protocol for unicast packet delivery in a MANET. Unlike(More)
In this paper, we propose the hierarchical daisy architecture, which provides causal delivery of messages sent to any subset of processes. The architecture provides fault tolerance and maintains the amount of control information within a reasonable size. It divides processes into logical groups. Messages inside a logical group are sent directly, while(More)
In this paper we outline a novel approach for enhancing content-based routing performance in publish/subscribe systems composed by an application-level network of event brokers. We present an algorithm which aim is to logically place close (in terms of TCP hops) brokers that manage subscribers with similar interests. We show how this algorithm allows the(More)
Low-latency data delivery is an important requirement for achieving effective monitoring through wireless sensor networks. When sensor nodes employ duty cycling, sending a message along the shortest path, however, does not necessarily result in minimum delay. In this paper, we first study the lowest latency path problem, i.e., the characteristics of a path(More)
In this paper we present a novel probabilistic protocol for path discovery in Mobile Ad Hoc Networks (MANETs). The protocol implements what we call a polarized gossiping algorithm. While in the classical gossip algorithm each node forwards a message with the same probability, our proposal is characterized by a variable gossiping probability, which is high(More)
The decoupling and asynchrony properties of the content-based publish-subscribe paradigm makes it very appealing for dynamic wireless networks, like those that often occur in pervasive computing scenarios. Unfortunately, most of the currently available content-based publish-subscribe middleware do not fit the requirements of such extreme scenarios, in which(More)
The notion of temporal uncertainty, expressed as the possibility for an event to occur in an interval of simulation time, rather than at a specific instant, has been recently proposed and exploited in order to enhance the performance of parallel/distributed simulation systems. In this paper we propose the concept of "spatial uncertainty" expressed as the(More)