1,721,556 research outputs found
Implementing a replicated service with group communication
No full textDistributed computing systems are quickly pervading many aspects of everyday life. The public demand for high reliability of these systems can only grow, together with their penetration in critical application domains. Group communication is a technology that may greatly simplifying the deployment of reliable distributed applications, even in environments composed of off-the-shelf hardware and software components. In this paper we attempt to provide an introductory and unified view to group communication. To make the presentation concrete, we shall analyze in detail how group communication may help in implementing a highly-available service based on replication. We shall consider a service whose interface allows determining the outcome of a non-idempotent operation previously submitted to the service, e.g., an update, that returned prematurely at the client because of a communication error - a key practical problem. We shall also provide a discussion of the performance that can be obtained in practice with group communication platforms. © 2003 Published by Elsevier B.V
Network architecture and ROA protection of government mail domains: A case study
Full text linkEmail is a crucial technology used in daily interactions of citizens, enterprises and organizations with their respective governments. In this work we are concerned with the country-wide network architecture of mail domains of public administrations. We analyze a dataset of government mail domains in Italy, Germany, the United Kingdom and the United States of America in order to investigate the opportunities for a network attacker to violate security properties of email communication, including availability, in large portions of a country. Issues of this kind are particularly relevant in times of high international tension and in which every country should treat its networks as a potential target for other countries.
We define a framework for describing the opportunities for a network attacker in the resolution of mail domain names, resolution of mail server names, access to a mail server. Based on this framework, we investigate in detail a number of issues related to redundancy and distribution of dependencies among networks and autonomous systems. We also analyze the usage in the access to mail domains of Route Origin Authorization (ROA), an important defensive technology for detecting attacks at the IP routing level. Our analysis allows gaining important insights into the actual network architecture of such an important piece of critical infrastructure as government mail domains
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
DIALOGO SU FARM CULTURAL PARK
No full textFarm Cultural Park è oggi un esempio di rigenerazione urbana riconosciuto in tutto il mondo, che si arricchisce ogni giorno di nuovi progetti e iniziative e a cui aderiscono sempre più artisti, professionisti e creativi. Proprio in virtù di questa unicità, l'UdR di Palermo del PRIN "Re-cycle Italy. Nuovi cicli di vita per architetture e infrastrutture della città e del paesaggio", ha voluto presentare questa buona pratica - caso esemplare di "re-cycle" - all'interno della ricerca di interesse nazionale, descrivendola attraverso le parole del suo stesso fondatore. Il contributo, pertanto, sotto forma di dialogo, racconta l'idea, il processo e i futuri di Farm Cultural Park
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