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The population of the elderly people has kept increasing rapidly over the world in the past decades. Solutions that are able to effectively support the elderly people to live independently at their home are thus urgently needed. Ambient assisted living (AAL) aims to provide products and services with ambient intelligence to build a safe environment around people in need. With the high prevalence of multiple chronic diseases, the elderly people often need different levels of care management to prolong independent living at home. An effective AAL system should provide the required clinical support as an extension to the services provided in hospitals. Following the rapid growth of available data, together with the wide application of machine learning technologies, we are now able to build intelligent ambient assisted systems to fulfil such a request. This paper discusses different levels of intelligence in AAL. We also introduce our solution for building an intelligent AAL system with the discussed technologies. Taking semantic web technology as its backbone, such an AAL system is able to aggregate information from different sources, solve the semantic gap between different data sources, and perform adaptive and personalized carepath management based on the ambient environment.

When programming resource-scarce embedded smart devices, the designer often requires both the low-level system programming features of a language such as C and higher level capability typical of a language like Java. The choice of a particular language typically implies trade offs between conflicting design goals such as performance, costs, and overheads. The large variety of languages, virtual machines, and translators provides the designer with a dense trade off space, ranging from minimalistic to rich full-fledged approaches, but once a choice is made it is often difficult for the designer to revise it. In this work we propose a system of light-weighted and modular extensions as a method to flexibly reshape the target programming language as needed, adding only those application layer features that match the current design goals. In so doing complexity is made transparent, but not hidden: While the programmer can benefit of higher level constructs, the designer can deal with modular building blocks each characterized by a certain algorithmic complexity and therefore each accountable for a given share of the overhead. As a result the designer is given a finer control on the amount of resources that are consumed by the run-time executive of the chosen programming language., Comment: Appeared in Proc. of the 3rd Int.l Conference on Advanced Communication and Networking (ACN 2011), Lecture Notes in Computer Science. Springer

This paper describes a novel approach for the flexible development of dependable automation services applied to a case study taken from requirements of energy automation systems. It shows first how the use of a custom compositional recovery language can be exploited to achieve a flexible and dependable functionality in software. Then it is shown how modeling techniques based on Petri nets can be used to assess the properties that different configurations of the addressed service can achieve., Comment: The final version of this paper appeared in the Proceedings of the 2002 Conference on the Engineering of Computer Based Systems (ECBS-2002). arXiv admin note: text overlap with arXiv:1611.02273

Traditional social organizations such as those for the management of healthcare are the result of designs that matched well with an operational context considerably different from the one we are experiencing today. The new context reveals all the fragility of our societies. In this paper, a platform is introduced by combining social-oriented communities and complex-event processing concepts: SELFSERV. Its aim is to complement the "old recipes" with smarter forms of social organization based on the self-service paradigm and by exploring culture-specific aspects and technological challenges., Comment: Final version of a paper published in the Proceedings of International Conference on Software Development and Technologies for Enhancing Accessibility and Fighting Info-exclusion (DSAI'16), special track on Emergent Technologies for Ambient Assisted Living (ETAAL)

The central topic of this book is application-level fault-tolerance, that is the methods, architectures, and tools that allow to express a fault-tolerant system in the application software of our computers. Application-level fault-tolerance is a sub-class of software fault-tolerance that focuses on the problems of expressing the problems and solutions of fault-tolerance in the top layer of the hierarchy of virtual machines that constitutes our computers. This book shows that application-level fault-tolerance is a key ingredient to craft truly dependable computer systems--other approaches, such as hardware fault-tolerance, operating system fault-tolerance, or fault-tolerant middleware, are also important ingredients to achieve resiliency, but they are not enough. Failing to address the application layer means leaving a backdoor open to problems such as design faults, interaction faults, or malicious attacks, whose consequences on the quality of service could be as unfortunate as, e.g., a physical fault affecting the system platform. In other words, in most cases it is simply not possible to achieve complete coverage against a given set of faults or erroneous conditions without embedding fault-tolerance provisions also in the application layer., Comment: Preprint of "Application-layer Fault-Tolerance Protocols", De Florio V., IGI Global, Hershey, PA 17033, USA, January 2009. ISBN: 978-1-60566-182-7. 378 pages. arXiv admin note: substantial text overlap with arXiv:1611.01690

The structures for the expression of fault-tolerance provisions into the application software are the central topic of this dissertation. Structuring techniques 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. A first contribution of this dissertation is the definition of 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 need. This result is then used to provide an elaborated survey of the state-of-the-art of software fault-tolerance structures. The key contribution of this work is a novel structuring technique for the expression of the fault-tolerance design concerns in the application layer of those distributed software systems that are characterized by soft real-time requirements and with a number of processing nodes known at compile-time. The main thesis of this dissertation is that this new structuring technique is capable of exhibiting satisfactory values of the structural attributes in the domain of soft real-time, distributed and parallel applications. Following this novel approach, beside the conventional programming language addressing the functional design concerns, a special-purpose linguistic structure (the so-called "recovery language") is available to address error recovery and reconfiguration. This recovery language comes into play as soon as an error is detected by an underlying error detection layer, or when some erroneous condition is signaled by the application processes., Comment: Doctoral thesis, successfully defended on October 13, 2000

At our behest or otherwise, while our software is being executed, a huge variety of design assumptions is continuously matched with the truth of the current condition. While standards and tools exist to express and verify some of these assumptions, in practice most of them end up being either sifted off or hidden between the lines of our codes. Across the system layers, a complex and at times obscure web of assumptions determines the quality of the match of our software with its deployment platforms and run-time environments. Our position is that it becomes increasingly important being able to design software systems with architectural and structuring techniques that allow software to be decomposed to reduce its complexity, but without hiding in the process vital hypotheses and assumptions. In this paper we discuss this problem, introduce three potentially dangerous consequences of its denial, and propose three strategies to facilitate their treatment. Finally we propose our vision towards a new holistic approach to software development to overcome the shortcomings offered by fragmented views to the problem of assumption failures., Comment: In "Architecting Dependable Systems, Vol. 7" (Antonio Casimiro, Rog\'erio de Lemos, and Cristina Gacek, Eds.), Lecture Notes in Computer Science, Vol. 6420. Springer, 2010

This document describes a class of C functions implementing a distributed software voting mechanism for EPX or similar message passing multi-threaded environments. Such a tool may be used for example, to set up a restoring organ, i.e., an NMR (i.e., N-module redundant) system with N voters. In order to describe the tool we start defining its basic building block, the voter. A voter is defined as a software module connected to one user module and to a farm of fellow voters arranged into a clique. By means of the functions in the class the user module is able: to create a static "picture" of the voting farm, needed for the set up of the clique; to instantiate the local voter; to send input or control messages to that voter. No interlocutor is needed other than the local voter. The other user modules are supposed to create coherent pictures and instances of voters on other nodes of the machine and to manage consistently the task of their local intermediary. All technicalities concerning the set up of the clique and the exchange of messages between the voters are completely transparent to the user module. In the following the basic functionalities of the VotingFarm class will be discussed, namely how to set up a "passive farm", or a non-alive topological representation of a yet-to-be-activated voting farm; how to initiate the voting farm; how to control the farm., Comment: Revised version of Technical Report ESAT/ACCA/1997/3, ESAT Dept., University of Leuven, Belgium

This paper proposes a design tool to investigate the properties and emergent behaviours of a special class of Ambient Assisted Living systems, namely mutual assistance communities where the dwellers contribute to each other's well being. Purpose of our system is to understand how mutual assistance communities work, what consequences a design decision could ultimately bring about, and how to construct care communities providing timely and cost-effective service for elderly and disabled people. We prove that mutual assistance between dwellers can provide care in time, and decrease the requirement for professional medical service. The simulation results show that with the existing rules most of the requirements for help can be solved or promptly initiated inside the community before their members resort to external professionals., Comment: In Proc. of the 6th Int.l Conference on Intelligent Systems Design and Applications (ISDA'06), October 16-18, 2006, Jinan, Shandong, China

In the framework of the ESPRIT project 28620 "TIRAN" (tailorable fault tolerance frameworks for embedded applications), a toolset of error detection, isolation, and recovery components is being designed to serve as a basic means for orchestrating application-level fault tolerance. These tools will be used either as stand-alone components or as the peripheral components of a distributed application, that we call 'the backbone". The backbone is to run in the background of the user application. Its objectives include (1) gathering and maintaining error detection information produced by TIRAN components like watchdog timers, trap handlers, or by external detection services working at kernel or driver level, and (2) using this information at error recovery time. In particular, those TIRAN tools related to error detection and fault masking will forward their deductions to the backbone that, in turn, will make use of this information to orchestrate error recovery, requesting recovery and reconfiguration actions to those tools related to error isolation and recovery. Clearly a key point in this approach is guaranteeing that the backbone itself tolerates internal and external faults. In this article we describe one of the means that are used within the TIRAN backbone to fulfill this goal: a distributed algorithm for tolerating crash failures triggered by faults affecting at most all but one of the components of the backbone or at most all but one of the nodes of the system. We call this the algorithm of mutual suspicion., Comment: Appeared in the Proceedings of the 7th Annual IEEE Int.l Conference and Workshop on the Engineering of Computer Based Systems (ECBS 2000), Edinburgh, Scotland, April 3, 2000

An application-level technique is described for farmer-worker parallel applications which allows a worker to be added or removed from the computing farm at any moment of the run time without affecting the overall outcome of the computation. The technique is based on uncoupling the farmer from the workers by means of a separate module which asynchronously feeds these latter with new "units of work" on an on-demand basis, and on a special feeding strategy based on bookkeeping the status of each work-unit. An augmentation of the LINDA model is finally proposed to exploit the bookkeeping algorithm for tuple management., Comment: In LNCS 1225 (1997), Proc. of the High-Performance Computing and Networking Conference ISBN: 978-3-540-62898-9 (Print) 978-3-540-69041-2 (Online)

Pervasive social computing is a promising approach that promises to empower both the individual and the whole and thus candidates itself as a foundation to the "smarter" social organizations that our new turbulent and resource-scarce worlds so urgently requires. In this contribution we first identify those that we consider as the major requirements to be fulfilled in order to realize an effective pervasive social computing infrastructure. We then conjecture that our service-oriented community and fractal social organization fulfill those requirements and therefore constitute an effective strategy to design pervasive social computing infrastructures. In order to motivate our conjecture, in this paper we discuss a model of social translucence and discuss fractal social organization as a referral service empowering a social system's parts and whole., Comment: The paper makes use, in minimal part, of text and pictures from papers [18,19,20,21]. Figure 1 is (c) Copyright Okefenokee Glee & Perloo, Inc. It is used by permission

Are purely technological solutions the best answer we can get to the shortcomings our organizations are often experiencing today? The results we gathered in this work lead us to giving a negative answer to such question. Science and technology are powerful boosters, though when they are applied to the "local, static organization of an obsolete yesterday" they fail to translate in the solutions we need to our problems. Our stance here is that those boosters should be applied to novel, distributed, and dynamic models able to allow us to escape from the local minima our societies are currently locked in. One such model is simulated in this paper to demonstrate how it may be possible to tap into the vast basins of social energy of our human societies to realize ubiquitous computing sociotechnical services for the identification and timely response to falls., Comment: Submitted to the 17th Int.l Conf. on Information Integration and Web-based Applications & Services (iiWAS2015)

Nowadays, more and more applications require OSGi to have some form of real-time support, which is currently very limited. The resulting closed-system solutions lack of a standard management scheme which forbids standard, system-wide policies for real-time system's deployment, adaptation, and reconfiguration. In order to tackle this problem, this paper proposes a declarative real-time component model. In this model, the distinguishing real-time contract of each component is declaratively described, and a general component real-time management interface is designed. They are used to maintain an accurate view of existing real-time components' promised contracts. A real-time component runtime service is designed to control the whole lifecycle of the components. By using global information and general control interface, it can adjust the system continue to operate without impairing the deployed components' real-time contracts in the face of run-time changes. This system allows itself to be easily extended with other constraint resolving policies to fit different context. The prototype has been tested into a simulated control system. The result shows this framework can provide good real time performance while still provides real-time component dynamicity support as well. To the best of our knowledge, this is the first comprehensive solution providing explicit real-time support from design to execution in OSGi framework., Comment: Published in Proc. of the 7th workshop on Reflective and adaptive middleware (ARM-08). Authors' version

Classic approaches to General Systems Theory often adopt an individual perspective and a limited number of systemic classes. As a result, those classes include a wide number and variety of systems that result equivalent to each other. This paper introduces a different approach: First, systems belonging to a same class are further differentiated according to five major general characteristics. This introduces a "horizontal dimension" to system classification. A second component of our approach considers systems as nested compositional hierarchies of other sub-systems. The resulting "vertical dimension" further specializes the systemic classes and makes it easier to assess similarities and differences regarding properties such as resilience, performance, and quality-of-experience. Our approach is exemplified by considering a telemonitoring system designed in the framework of Flemish project "Little Sister". We show how our approach makes it possible to design intelligent environments able to closely follow a system's horizontal and vertical organization and to artificially augment its features by serving as crosscutting optimizers and as enablers of antifragile behaviors., Comment: Accepted for publication in the Journal of Reliable Intelligent Environments. Extends conference papers [10,12,15]. The final publication is available at Springer via http://dx.doi.org/10.1007/s40860-015-0006-2

The population of elderly people keeps increasing rapidly, which becomes a predominant aspect of our societies. As such, solutions both efficacious and cost-effective need to be sought. Ambient Assisted Living (AAL) is a new approach which promises to address the needs from elderly people. Ambient Intelligence technologies are widely developed in this domain aiming to construct safe environments around assisted peoples and help them maintain independent living. However, there are still many fundamental issues in AAL that remain open. Most of the current efforts still do not fully express the power of human being, and the importance of social connections and social activities is less noticed. Our conjecture is that such features are fundamental prerequisites towards truly effective AAL services. This paper reviews the current status of researches on AAL, discusses the promises and possible advantages of AAL, and also indicates the challenges we must meet in order to develop practical and efficient AAL systems for elderly people. In this paper, we also propose an approach to construct effective home-care system for the elderly people., Comment: Published in the Proc. of the 6th Int.l Conference on Information Technology: New Generations (ITNG 2009), April 27-29, 2009, Las Vegas, Nevada, USA. IEEE

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., Comment: Paper presented at the 20th Euromicro International Conference on Parallel, Distributed and Network-Based Processing

A number of elements towards a classification of the quality of emergence in emergent collective systems are provided. By using those elements, several classes of emergent systems are exemplified, ranging from simple aggregations of simple parts up to complex organizations of complex collective systems. In so doing, the factors likely to play a a significant role in the persistence of emergence and its opposite are highlighted. From this, new elements for discussion are identified also considering elements from the System of Leibniz., Comment: Paper accepted for publication in Mohammad Essaaidi, Mohamed Nemiche (Eds.) "Advances in Complex Societal, Environmental and Engineered Systems", Springer series "Nonlinear Systems and Complexity", Springer, 2016

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"., Comment: Draft of an invited paper for PEWET (1st Workshop on PErvasive WEb Technologies, trends and challenges), http://www.irpps.cnr.it/en/events/call-for-papers-pewet-pervasive-web-technologies-trends-and-challenges

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., Comment: Paper submitted for publication in the Proc. of SERENE 2015 (http://serene.disim.univaq.it/2015/)

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., Comment: This is a revision of Technical Report ESAT/ACCA/1998/1, Katholieke Universiteit Leuven, 1998

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., Comment: In Proc. of the Sixth IEEE Int.l Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM 2005)

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., Comment: Published in the Proc. of the 7th Int.l IET System Safety Conference, Edinburgh, UK, 15-18 October 2012. IET

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., Comment: Published in Int.l Journal of Business Intelligence and Data Mining, Vol. 3, No. 3 (2008). Inderscience. 20 pages

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., Comment: Published in IET Software, Vol. 4, No. 2, April 2010. Institution of Engineering and Technology (IET). 14 pages

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., Comment: Paper published in the Journal of Systems Architecture, Vol. 52 (2006). Elsevier

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., Comment: Paper appeared in ACM Computing Surveys, Vol. 40, No. 2 (April 2008)

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., Comment: The final publication is available at Springer via http://dx.doi.org/10.1007/s40860-015-0002-6 The paper considerably extends the results of two conference papers that are available at http://ow.ly/KWfkj and http://ow.ly/KWfgO. Text and formalism in those papers has been used or adapted in the herewith submitted paper

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., Comment: Draft version of a paper accepted for publication in the Proceedings of to ANTIFRAGILE 2015 (2nd International Workshop on Computational Antifragility and Antifragile Engineering, https://sites.google.com/site/antifragile15/)

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., Comment: Preliminary version of a chapter to appear in a forthcoming book edited by Robert Macdougall and to be published by Lexington in 2015

Aim of this paper is to provide preliminary elements for discussion about the implications of the Hierarchy Theory of Evolution on the design and evolution of artificial systems and socio-technical organizations. In order to achieve this goal, a number of analogies are drawn between the System of Leibniz; the socio-technical architecture known as Fractal Social Organization; resilience and related disciplines; and Hierarchy Theory. In so doing we hope to provide elements for reflection and, hopefully, enrich the discussion on the above topics with considerations pertaining to related fields and disciplines, including computer science, management science, cybernetics, social systems, and general systems theory., Comment: To appear in the Proceedings of ANTIFRAGILE'17, 4th International Workshop on Computational Antifragility and Antifragile Engineering

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., Comment: Pre-camera-ready paper to appear in the Proceedings of WCCS 2014 (2nd World Conference on Complex Systems)

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., Comment: Paper appeared in the Proc. of the IEEE Conference "Wiener in the 21st Century". Companion paper of http://arxiv.org/abs/1403.0339

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., Comment: Draft submitted for publication in the Proceedings of the IEEE 2014 Conference on Norbert Wiener in the 21st Century

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., Comment: In submission(revised version) to Technological Forecasting & Social Change

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., Comment: Preliminary version submitted to the 1st International Workshop "From Dependable to Resilient, from Resilient to Antifragile Ambients and Systems" (ANTIFRAGILE 2014), https://sites.google.com/site/resilience2antifragile/

The embedding of fault tolerance provisions into the application layer of a programming language is a non-trivial task that has not found a satisfactory solution yet. Such a solution is very important, and the lack of a simple, coherent and effective structuring technique for fault tolerance has been termed by researchers in this field as the "software bottleneck of system development". The aim of this paper is to report on the current status of a novel fault tolerance linguistic structure for distributed applications characterized by soft real-time requirements. A compliant prototype architecture is also described. The key aspect of this structure is that it allows to decompose the target fault-tolerant application into three distinct components, respectively responsible for (1) the functional service, (2) the management of the fault tolerance provisions, and (3) the adaptation to the current environmental conditions. The paper also briefly mentions a few case studies and preliminary results obtained exercising the prototype., Comment: Proc. of the 9th IEEE Conf. and Workshop on Engineering of Computer-Based Systems (ECBS-2002), Lund, Sweden, 8-11 April, 2002; pp. 51-58

Elder people are becoming a predominant aspect of our societies. As such, solutions both efficacious and cost-effective need to be sought. This paper proposes a service-oriented infrastructure approach to this problem. We propose an open and integrated service infrastructure to orchestrate the available resources (smart devices, professional carers, informal carers) to help elder or disabled people. Main characteristic of our design is the explicitly support of dynamically available service providers such as informal carers. By modeling the service description as Semantic Web Services, the service request can automatically be discovered, reasoned about and mapped onto the pool of heterogeneous service providers. We expect our approach to be able to efficiently utilize the available service resources, enrich the service options, and best match the requirements of the requesters., Comment: Proc. of the First IEEE WoWMoM Workshop on Adaptive and DependAble Mission- and bUsiness-critical mobile Systems (ADAMUS'07), Helsinki, Finland, June 18, 2007

With the increase of the populations, resources are becoming scarcer, and a smarter way to make use of them becomes a vital necessity of our societies. On the other hand, resource management is traditionally carried out through well established organizations, policies, and regulations that are often considered as impossible to restructure. Our position is that merely expanding the traditional approaches might not be enough. Systems must be radically rethought in order to achieve a truly effective and rational use of the available resources. Classical concepts such as demand and supply need to be rethought as well, as they operate artificial classifications that limit the true potential of systems and organizations. In what follows we propose our vision to future, "smarter" systems able to overcome the limitations of the status quo. Such systems require what Boulding called "gestalts," namely concepts able to "directing research towards the gaps which they reveal". In this paper we elaborate on this and show how such gestalts can pave the way towards novel reformulations of traditional services able to reach a better and more sensible management of the available resources and cope with their scarcity. Our vision of a Service-oriented Community is also introduced. We believe that such communities---in heterarchical coexistence with traditional systems---provide the necessary diversity and innovation orientation to prevent societal lock-ins such as the ones we are experiencing in assisting our elderly ones., Comment: Proc. of the Fifth Int.l Workshop on MObile and NEtworking Technologies for social applications (MONET 2010), Lecture Notes in Computer Science, Volume 6428/2010, pp. 319-328, October 25-29, 2010, Crete, Greece

We propose a simple and effective tool for the expression of tasks such as cross-layer optimization strategies or sensors-related applications. The approach is based on what we refer to as "reflective and refractive variables". Both types of variables are associated with external entities, e.g. sensors or actuators. A reflective variable is a volatile variable, that is, a variable that might be concurrently modified by multiple threads. A library of threads is made available, each of which interfaces a set of sensors and continuously update the value of a corresponding set of sensors. One such thread is "cpu", which exports the current level of usage of the local CPU as an integer between 0 and 100. This integer is reflected into the integer reflective variable cpu. A refractive variable is a reflective variable that can be modified. Each modification is caught and interpreted as a request to change the value of an actuator. For instance, setting variable "tcp_sendrate" would request a cross-layer adjustment to the thread interfacing the local TCP layer entity. This allows express in an easy way complex operations in the application layer of any programming language, e.g. plain old C. We describe our translator and the work we are carrying out within PATS to build simple and powerful libraries of scripts based on reflective and refractive variables, including robotics applications and RFID tags processing., Comment: Proc. of the 33rd Euromicro Conference on Software Engineering and Advanced Applications (SEEA 2007), L\"ubeck, Germany, August 27-31 2007

We describe the voting farm, a tool which implements a distributed software voting mechanism for a number of parallel message passing systems. The tool, developed in the framework of EFTOS (Embedded Fault-Tolerant Supercomputing), can be used in stand-alone mode or in conjunction with other EFTOS fault tolerance tools. In the former case, we describe how the mechanism can be exploited, e.g., to implement restoring organs ($N\!$-modular redundancy systems with $N\!$-replicated voters); in the latter case, we show how it is possible for the user to implement in an easy and effective way a number of different recovery strategies via a custom, high-level language. Combining such strategies with the basic fault masking capabilities of the voting tool makes it possible to set up complex fault-tolerant systems such as, for instance, $N$-and-$M$-spare systems or gracefully degrading voting farms. We also report about the impact that our tool can have on reliability, and we show how, besides structural design goals like fault transparency, our tool achieves replication transparency, a high degree of flexibility and ease-of-use, and good performance.

We describe a distributed, multimedia application which is being developed in the framework of the ESPRIT-IV Project 21012 EFTOS (Embedded Fault-Tolerant Supercomputing). The application dynamically sets up a hierarchy of HTML pages reflecting the current status of an EFTOS-compliant dependable application running on a Parsytec CC system. These pages are fed to a World-Wide Web browser playing the role of a hypermedia monitor. The adopted approach allows the user to concentrate on the high-level aspects of his/her application so to quickly assess the quality of its current fault-tolerance design. This view of the system lends itself well for being coupled with a tool to interactively inject software faults in the user application; this tool is currently under development., Comment: Proc. of the 6th Conf. on Parallel and Distributed Processing (PDP98)

We present a set of C functions implementing a distributed software voting mechanism for EPX or similar message passing environments, and we place it within the EFTOS framework (Embedded Fault-Tolerant Supercomputing, ESPRIT-IV Project 21012) of software tools for enhancing the dependability of a user application. The described mechanism can be used for instance to implement restoring organs i.e., N-modular redundancy systems with N-replicated voters. We show that, besides structural design goals like fault transparency, this tool achieves replication transparency, a high degree of flexibility and ease-of-use, and good performance., Comment: Proc. of the 24th EUROMICRO Conf. on Engineering Systems and Software for the next decade, Vaesteras, Sweden, August 25-27, 1998; pp. 379-386

Elder people are becoming a predominant aspect of our societies. As such, solutions both efficacious and cost-effective need to be sought. The approach pursued so far to solve this problem used to increase the number of people working in the health sector, e.g. doctors, nurses, etc. This increases the costs, which is becoming a big burden for countries. In this paper we propose a new concept in the health management of elder people, which we name as "participant". We propose the "participant" concept to encourage elder people to participate in those group activities that they are able to. Their roles in these activities are not passively requesting help, but actively participating to some healthcare processes. Characteristics of the participant approach are that medical resources are efficiently spared with this model, and the social network of the elder people is kept. A "virtual community" for mutual assistance is set up in this paper, and the simulations demonstrate that the "participant" model could fully utilize the community resources. Furthermore, the psychological health of the elder people will be improved., Comment: Twentieth IEEE International Symposium on Computer-Based Medical Systems, 2007. CBMS '07

The population of elderly people keeps increasing rapidly, which becomes a predominant aspect of our societies. As such, solutions both efficacious and cost-effective need to be sought. Ambient Assisted Living (AAL) is a new approach which promises to address the needs from elderly people. In this paper, we claim that human participation is a key ingredient towards effective AAL systems, which not only saves social resources, but also has positive relapses on the psychological health of the elderly people. Challenges in increasing the human participation in ambient assisted living are discussed in this paper and solutions to meet those challenges are also proposed. We use our proposed mutual assistance community, which is built with service oriented approach, as an example to demonstrate how to integrate human tasks in AAL systems. Our preliminary simulation results are presented, which support the effectiveness of human participation.