Abstract
This paper presents a distributed algorithm to simultaneously compute the diameter, radius and node eccentricity in all nodes of a synchronous network. Such topological information may be useful as input to configure other algorithms. Previous approaches have been modular, progressing in sequential phases using building blocks such as BFS tree construction, thus incurring longer executions than strictly required. We present an algorithm that, by timely propagation of available estimations, achieves a faster convergence to the correct values. We show local criteria for detecting convergence in each node. The algorithm avoids the creation of BFS trees and simply manipulates sets of node ids and hop counts. For the worst scenario of variable start times, each node i with eccentricity ecc(i) can compute: the node eccentricity in diam(G)+ecc(i)+2 rounds; the diameter in 2 diam(G)+ecc(i)+ 2 rounds; and the radius in diam(G) + ecc(i) + 2 radius(G) rounds.

Abstract
The distributed aggregation of simple aggregates such as minima/maxima, counts, sums and averages have been studied in the past and are important tools for distributed algorithms and network coordination. Nonetheless, this kind of aggregates may not be comprehensive enough to characterize biased data distributions or when in presence of outliers, making the case for richer estimates. This work presents Spectra, a distributed algorithm for the estimation of distribution functions over large scale networks. The estimate is available at all nodes and the technique depicts important properties: robustness when exposed to high levels of message loss, fast convergence speed and fine precision in the estimate. It can also dynamically cope with changes of the sampled local property and with churn, without requiring restarts. The proposed approach is experimentally evaluated and contrasted to a competing state of the art distribution aggregation technique. © 2012 IFIP International Federation for Information Processing.

Abstract

Abstract
Version vectors (VV) are used pervasively to track dependencies between replica versions in multi-version distributed storage systems. In these systems, VV tend to have a dual functionality: identify a version and encode causal dependencies. In this paper, we show that by maintaining the identifier of the version separate from the causal past, it is possible to verify causality in constant time (instead of O(n) for VV) and to precisely track causality with information with size bounded by the degree of replication, and not by the number of concurrent writers. © 2012 Authors.

Abstract
Quality assessment of open source software is becoming an important and active research area. One of the reasons for this recent interest is the consequence of Internet popularity. Nowadays, programming also involves looking for the large set of open source libraries and tools that may be reused when developing our software applications. In order to reuse such open source software artifacts, programmers not only need the guarantee that the reused artifact is certified, but also that independently developed artifacts can be easily combined into a coherent piece of software. In this paper we describe a domain specific language that allows programmers to describe in an abstract level how software artifacts can be combined into powerful software certification processes. This domain specific language is the building block of a web-based, open-source software certification portal. This paper introduces the embedding of such domain specific language as combinator library written in the Haskell programming language. The semantics of this language is expressed via attribute grammars that are embedded in Haskell, which provide a modular and incremental setting to define the combination of software artifacts.

Abstract
This paper presents a web portal for the certification of open source software. The portal aims at helping programmers in the internet age, when there are (too) many open source reusable libraries and tools available. Our portal offers programmers a web-based and easy setting to analyze and certify open source software, which is a crucial step to help programmers choosing among many available alternatives, and to get some guarantees before using one piece of software. The paper presents our first prototype of such web portal. It also describes in detail a domain specific language that allows programmers to describe with a high degree of abstraction specific open source software certifications. The design and implementation of this language is the core of the web portal. © Springer-Verlag Berlin Heidelberg 2014.