Roberto Baldoni

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Today we are witnessing a dramatic shift toward a data-driven economy, where the ability to efficiently and timely analyze huge amounts of data marks the difference between industrial success stories and catastrophic failures. In this scenario Storm, an open source distributed realtime computation system, represents a disruptive technology that is quickly(More)
Considering an application in which processes take local checkpoints independently (called basic checkpoints), this paper develops a protocol that forces them to take some additional local checkpoints (called forced checkpoints) in order that the resulting checkpoint and communication pattern satisfies the Rollback Dependency Trackability (RDT) property.(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)
This paper introduces a novel architecture for implementing content-based pub/sub communications on top of structured overlay networks. This architecture overcomes some well-known limitations of existing infrastructures, i.e. lack of self-configuration and of adaptiveness to dynamic changes. This is achieved by devising a mediator stratum between the rich(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)
In cooperative information systems, the quality of data exchanged and provided by different data sources is extremely important. A lack of attention to data quality can imply data of low quality to spread all over the cooperative system. At the same time, improvement can be based on comparing data, correcting them and thus disseminating high quality data.(More)
This paper presents an index based checkpointing algorithm for distributed systems with the aim of reducing the total number of checkpoints while ensuring that each checkpoint belongs to at least one consistent global checkpoint or recovery line The algorithm is based on an equivalence relation de ned between pairs of successive checkpoints of a process(More)
This paper presents a consensus protocol resilient to Byzantine failures. It uses signed and certified messages and is based on two underlying failure detection modules. The first is an unreliable failure detector module of the class 3S(bz). The second is a reliable arbitrary behavior detection module. More precisely, the first module detects processes that(More)
Considering a checkpoint and communication pattern, the rollback-dependency trackability (RDT) property stipulates that there is no hidden dependency between local checkpoints. In other words, if there is a dependency between two checkpoints due to a noncausal sequence of messages (Z-path), then there exists a causal sequence of messages (C-path) that(More)
A useless checkpoint corresponds to the occurrence of a checkpoint and communication pattern called Z-cycle. A recent result shows that ensuring a computation without Z-cycles is a particular application of a property, namely Virtual Precedence (VP), defined on an interval-based abstraction of a computation. In this paper we first propose a taxonomy of(More)