arXiv subjects

Vincenzo De Florio

Publications and source records attributed to Vincenzo De Florio.

At least 37 records · Page 2Linked to original sources

arXiv2015

Robust and Tuneable Family of Gossiping Algorithms

We present a family of gossiping algorithms whose members share the same structure though they vary their performance in function of a combinatorial parameter. We show that such parameter may be considered as a "knob" controlling the amount of communication parallelism characterizing the algorithms. After this we introduce procedures to operate the knob and choose parameters matching the amount of communication channels currently provided by the available communication system(s). In so doing we provide a robust mechanism to tune the production of requests for communication after the current operational conditions of the consumers of such requests. This can be used to achieve high performance and programmatic avoidance of undesirable events such as message collisions.

cs.DC↗

arXiv2015

Reflections on organization, emergence, and control in sociotechnical systems

Human and artificial organizations may be described as networks of interacting parts. Those parts exchange data and control information and, as a result of these interactions, organizations produce emergent behaviors and purposes -- traits the characterize "the whole" as "greater than the sum of its parts". In this chapter it is argued that, rather than a static and immutable property, emergence should be interpreted as the result of dynamic interactions between forces of opposite sign: centripetal (positive) forces strengthening emergence by consolidating the whole and centrifugal (negative) forces that weaken the social persona and as such are detrimental to emergence. The result of this interaction is called in this chapter as "quality of emergence". This problem is discussed in the context of a particular class of organizations: conventional hierarchies. We highlight how traditional designs produce behaviors that may severely impact the quality of emergence. Finally we discuss a particular class of organizations that do not suffer from the limitations typical of strict hierarchies and result in greater quality of emergence. In some case, however, these enhancements are counterweighted by a reduced degree of controllability and verifiability.

cs.CY↗

arXiv2015

Behavior, Organization, Substance: Three Gestalts of General Systems Theory

The term gestalt, when used in the context of general systems theory, assumes the value of "systemic touchstone", namely a figure of reference used to categorize the properties or qualities of a set of systems. Typical gestalts used in biology are those based on anatomical or physiological characteristics, which correspond respectively to architectural and organizational design choices in natural and artificial systems. In this paper we discuss three gestalts of general systems theory: behavior, organization, and substance, which refer respectively to the works of Wiener, Boulding, and Leibniz. Our major focus here is the system introduced by the latter. Through a discussion of some of the elements of the Leibnitian System, and by means of several novel interpretations of those elements in terms of today's computer science, we highlight the debt that contemporary research still has with this Giant among the giant scholars of the past.

cs.OH↗

arXiv2015

Fractally-organized Connectionist Networks: Conjectures and Preliminary Results

A strict interpretation of connectionism mandates complex networks of simple components. The question here is, is this simplicity to be interpreted in absolute terms? I conjecture that absolute simplicity might not be an essential attribute of connectionism, and that it may be effectively exchanged with a requirement for relative simplicity, namely simplicity with respect to the current organizational level. In this paper I provide some elements to the analysis of the above question. In particular I conjecture that fractally organized connectionist networks may provide a convenient means to achive what Leibniz calls an "art of complication", namely an effective way to encapsulate complexity and practically extend the applicability of connectionism to domains such as sociotechnical system modeling and design. Preliminary evidence to my claim is brought by considering the design of the software architecture designed for the telemonitoring service of Flemish project "Little Sister".

cs.NE↗

arXiv2015

How Resilient Are Our Societies? Analyses, Models, and Preliminary Results

Traditional social organizations such as those for the management of healthcare and civil defence are the result of designs and realizations that matched well with an operational context considerably different from the one we are experiencing today: A simpler world, characterized by a greater amount of resources to match less users producing lower peaks of requests. The new context reveals all the fragility of our societies: unmanageability is just around the corner unless we do not complement the "old recipes" with smarter forms of social organization. Here we analyze this problem and propose a refinement to our fractal social organizations as a model for resilient cyber-physical societies. Evidence to our claims is provided by simulating our model in terms of multi-agent systems.

cs.OH↗

arXiv2015

The DIR Net: A Distributed System for Detection, Isolation, and Recovery

This document describes the DIR net, a distributed environment which is part of the EFTOS fault tolerance framework. The DIR net is a system consisting of two components, called DIR Manager (or, shortly, the manager) and DIR Backup Agent (shortly, the backup). One manager and a set of backups is located in the system to be `guarded', one component per node. At this point the DIR net weaves a web which substantially does two things: 1) makes itself tolerant to a number of possible faults, and 2) gathers information pertaining the run of the user application. As soon as an error occurs within the DIR net, the system executes built-in recovery actions that allow itself to continue processing despite a number of hardware/software faults, possibly doing a graceful degradation of its features; when an error occurs in the user application, the DIR net, by means of custom- and user-defined detection tools, is informed of such events and runs one or more recovery strategies, both built-in and coded by the user using an ancillary compile-time tool, the rl translator. Such tools translates the user-defined strategies into a binary `R-code', i.e., a pseudo-code interpreted by a special component of the DIR net, the Recovery Interpreter, rint (in a sense, rint is a r-code virtual machine.) This document describes the generic component of the DIR net, a function which can behave either as manager or as backup.

cs.DC↗

arXiv2015

A System Structure for Adaptive Mobile Applications

A system structure for adaptive mobile applications is introduced and discussed, together with a compliant architecture and a prototypic implementation. A methodology is also introduced, which exploits our structure to decompose the behavior of non stable systems into a set of quasi-stable scenarios. Within each of these scenarios we can exploit the knowledge of the available QoS figures to express simpler and better adaptation strategies.

cs.SE↗

arXiv2015

On the Requirements of New Software Development

Changes, they use to say, are the only constant in life. Everything changes rapidly around us, and more and more key to survival is the ability to rapidly adapt to changes. This consideration applies to many aspects of our lives. Strangely enough, this nearly self-evident truth is not always considered by software engineers with the seriousness that it calls for: The assumptions we draw for our systems often do not take into due account that e.g., the run-time environments, the operational conditions, or the available resources will vary. Software is especially vulnerable to this threat, and with today's software-dominated systems controlling crucial services in nuclear plants, airborne equipments, health care systems and so forth, it becomes clear how this situation may potentially lead to catastrophes. This paper discusses this problem and defines some of the requirements towards its effective solution, which we call "New Software Development" as a software equivalent of the well-known concept of New Product Development. The paper also introduces and discusses a practical example of a software tool designed taking those requirements into account --- an adaptive data integrity provision in which the degree of redundancy is not fixed once and for all at design time, but rather it changes dynamically with respect to the disturbances experienced during the run time.

cs.SE↗

arXiv2015

Safety enhancement through situation-aware user interfaces

Due to their privileged position halfway between the physical and the cyber universes, user interfaces may play an important role in preventing, tolerating, and learning from scenarios potentially affecting mission safety and the user's quality of experience. This vision is embodied here in the main ideas and a proof-of-concepts implementation of user interfaces that combine dynamic profiling with context- and situation-awareness and autonomic software adaptation.

cs.HC↗

arXiv2015

Design Tool To Express Failure Detection Protocols

Failure detection protocols---a fundamental building block for crafting fault-tolerant distributed systems---are in many cases described by their authors making use of informal pseudo-codes of their conception. Often these pseudo-codes use syntactical constructs that are not available in COTS programming languages such as C or C++. This translates into informal descriptions that call for ad hoc interpretations and implementations. Being informal, these descriptions cannot be tested by their authors, which may translate into insufficiently detailed or even faulty specifications. This paper tackles this problem introducing a formal syntax for those constructs and a C library that implements them---a tool-set to express and reason about failure detection protocols. The resulting specifications are longer but non ambiguous, and eligible for becoming a standard form.

cs.DC↗

arXiv2015

A Survey of Linguistic Structures for Application-level Fault-Tolerance

The structures for the expression of fault-tolerance provisions into the application software are the central topic of this paper. Structuring techniques answer the questions "How to incorporate fault-tolerance in the application layer of a computer program" and "How to manage the fault-tolerant code". As such, they provide means to control complexity, the latter being a relevant factor for the introduction of design faults. This fact and the ever increasing complexity of today's distributed software justify the need for simple, coherent, and effective structures for the expression of fault-tolerance in the application software. In this text we first define a "base" of structural attributes with which application-level fault-tolerance structures can be qualitatively assessed and compared with each other and with respect to the above mentioned needs. This result is then used to provide an elaborated survey of the state-of-the-art of application-level fault-tolerance structures.

cs.SE↗

arXiv2015

The Algorithm of Pipelined Gossiping

A family of gossiping algorithms depending on a parameter permutation is introduced, formalized, and discussed. Several of its members are analyzed and their asymptotic behaviour is revealed, including a member whose model and performance closely follows the one of hardware pipelined processors. This similarity is exposed. An optimizing algorithm is finally proposed and discussed as a general strategy to increase the performance of the base algorithms.

cs.DC↗

arXiv2015

On Resilient Behaviors in Computational Systems and Environments

The present article introduces a reference framework for discussing resilience of computational systems. Rather than a property that may or may not be exhibited by a system, resilience is interpreted here as the emerging result of a dynamic process. Said process represents the dynamic interplay between the behaviors exercised by a system and those of the environment it is set to operate in. As a result of this interpretation, coherent definitions of several aspects of resilience can be derived and proposed, including elasticity, change tolerance, and antifragility. Definitions are also provided for measures of the risk of unresilience as well as for the optimal match of a given resilient design with respect to the current environmental conditions. Finally, a resilience strategy based on our model is exemplified through a simple scenario.

eess.SY↗

arXiv2015

A framework for trustworthiness assessment based on fidelity in cyber and physical domains

We introduce a method for the assessment of trust for n-open systems based on a measurement of fidelity and present a prototypic implementation of a complaint architecture. We construct a MAPE loop which monitors the compliance between corresponding figures of interest in cyber- and physical domains; derive measures of the system's trustworthiness; and use them to plan and execute actions aiming at guaranteeing system safety and resilience. We conclude with a view on our future work.

cs.CR↗

arXiv2014

Mutualistic Relationships in Service-Oriented Communities and Fractal Social Organizations

In this paper we consider two social organizations -- service-oriented communities and fractal organizations -- and discuss how their main characteristics provide an answer to several shortcomings of traditional organizations. In particular, we highlight their ability to tap into the vast basins of "social energy" of our societies. This is done through the establishing of mutualistic relationships among the organizational components. The paper also introduces a mathematical model of said mutualistic processes as well as its translation in terms of semantic service description and matching. Preliminary investigations of the resilience of fractal social organizations are reported. Simulations show that fractal organizations outperform non-fractal organizations and are able to quickly recover from disruptions and changes characterizing dynamic environments.

cs.CY↗

arXiv2014

On the Behavioral Interpretation of System-Environment Fit and Auto-Resilience

Already 71 years ago Rosenblueth, Wiener, and Bigelow introduced the concept of the "behavioristic study of natural events" and proposed a classification of systems according to the quality of the behaviors they are able to exercise. In this paper we consider the problem of the resilience of a system when deployed in a changing environment, which we tackle by considering the behaviors both the system organs and the environment mutually exercise. We then introduce a partial order and a metric space for those behaviors, and we use them to define a behavioral interpretation of the concept of system-environment fit. Moreover we suggest that behaviors based on the extrapolation of future environmental requirements would allow systems to proactively improve their own system-environment fit and optimally evolve their resilience. Finally we describe how we plan to express a complex optimization strategy in terms of the concepts introduced in this paper.

cs.OH↗

arXiv2014

Quality Indicators for Collective Systems Resilience

Resilience is widely recognized as an important design goal though it is one that seems to escape a general and consensual understanding. Often mixed up with other system attributes; traditionally used with different meanings in as many different disciplines; sought or applied through diverse approaches in various application domains, resilience in fact is a multi-attribute property that implies a number of constitutive abilities. To further complicate the matter, resilience is not an absolute property but rather it is the result of the match between a system, its current condition, and the environment it is set to operate in. In this paper we discuss this problem and provide a definition of resilience as a property measurable as a system-environment fit. This brings to the foreground the dynamic nature of resilience as well as its hard dependence on the context. A major problem becomes then that, being a dynamic figure, resilience cannot be assessed in absolute terms. As a way to partially overcome this obstacle, in this paper we provide a number of indicators of the quality of resilience. Our focus here is that of collective systems, namely those systems resulting from the union of multiple individual parts, sub-systems, or organs. Through several examples of such systems we observe how our indicators provide insight, at least in the cases at hand, on design flaws potentially affecting the efficiency of the resilience strategies. A number of conjectures are finally put forward to associate our indicators with factors affecting the quality of resilience.

cs.CY↗

arXiv2014

Antifragility = Elasticity + Resilience + Machine Learning: Models and Algorithms for Open System Fidelity

We introduce a model of the fidelity of open systems - fidelity being interpreted here as the compliance between corresponding figures of interest in two separate but communicating domains. A special case of fidelity is given by real-timeliness and synchrony, in which the figure of interest is the physical and the system's notion of time. Our model covers two orthogonal aspects of fidelity, the first one focusing on a system's steady state and the second one capturing that system's dynamic and behavioural characteristics. We discuss how the two aspects correspond respectively to elasticity and resilience and we highlight each aspect's qualities and limitations. Finally we sketch the elements of a new model coupling both of the first model's aspects and complementing them with machine learning. Finally, a conjecture is put forward that the new model may represent a first step towards compositional criteria for antifragile systems.

cs.OH↗