Design Patterns to Build Large Resilient and Predictable Systems

The complexity of large computer systems has raised unprecedented challenges for system management. In practice, operators often collect large volume of monitoring data from system components and set up many rules to check data and trigger alerts. However, the alerts from various rules usually have different problem reporting accuracy because their thresholds are often manually set based on operators' experience and intuition. Meantime, due to system dependencies, a single problem may trigger many alerts at the same time in large systems and the critical question is which alert should be analyzed first in the following problem determination process. In this paper, we propose a novel peer review mechanism to rank the importance of alerts and the top ranked alerts are more likely to be true positives. After comparing a metric value against its threshold to generate alerts, we also compare the value with the equivalent thresholds from many other rules to determine the importance of alerts. Our approach is evaluated with a real test bed system and experimental results are also included to demonstrate its effectiveness.

Biomolecules are the prime information processing elements of living matter. Most of these inanimate systems are polymers that compute their own structures and dynamics using as input seemingly random character strings of their sequence, following which they coalesce and perform integrated cellular functions. In large computational systems with finite interaction-codes, the appearance of conflicting goals is inevitable. Simple conflicting forces can lead to quite complex structures and behaviors, leading to the concept of frustration in condensed matter. We present here some basic ideas about frustration in biomolecules and how the frustration concept leads to a better appreciation of many aspects of the architecture of biomolecules, and especially how biomolecular structure connects to function by means of localized frustration. These ideas are simultaneously both seductively simple and perilously subtle to grasp completely. The energy landscape theory of protein folding provides a framework for quantifying frustration in large systems and has been implemented at many levels of description. We first review the notion of frustration from the areas of abstract logic and its uses in simple condensed matter systems. We discuss then how the frustration concept applies specifically to heteropolymers, testing folding landscape theory in computer simulations of protein models and in experimentally accessible systems. Studying the aspects of frustration averaged over many proteins provides ways to infer energy functions useful for reliable structure prediction. We discuss how frustration affects folding mechanisms. We review here how the biological functions of proteins are related to subtle local physical frustration effects and how frustration influences the appearance of metastable states, the nature of binding processes, catalysis and allosteric transitions. In this review, we also emphasize that frustration, far from being always a bad thing, is an essential feature of biomolecules that allows dynamics to be harnessed for function. In this way, we hope to illustrate how Frustration is a fundamental concept in molecular biology.

A robust information infrastructure is required to collect power quality measurements and to execute corrective actions. It is based on a software architecture, designed at middleware level, that makes use of Internet protocols for communication over different media. While the middleware detects the anomalies in the communication and computation system and reacts appropriately, the application functionality is maintained through system reconfiguration or graceful degradation. Such anomalies may come from dynamic changes in the topology of the underlying communication system, or the enabling/disabling of processing nodes on the network. The added value of this approach comes from the flexibility to deal with a dynamic environment based on an unbounded system model. The paper illustrates this approach in a power quality measurement and control system with compensation based on active filters.

Peer-to-Peer (P2P) techniques for multimedia streaming have been shown to be a good enhancement to the traditional client/server methods when trying to reduce costs and increase robustness. Due to the fact that P2P systems are highly dynamic, the main challenge that has to be addressed remains supporting the general resilience of the system. Various challenges arise when building a resilient P2P streaming system, such as network failures and system dynamics. In this paper, we first classify the different challenges that face P2P streaming and then present and analyze the possible countermeasures. We classify resilience mechanisms as either core mechanisms, which are part of the system, or as cross-layer mechanisms that use information from different communication layers, which might inflict additional costs. We analyze and present resilience mechanisms from an engineering point of view, such that a system engineer can use our analysis as a guide to build a resilient P2P streaming system with different mechanisms and for various application scenarios.

This paper outlines a software architecture where zero-copy operations are used comprehensively at every processing point from the Application layer to the Physical layer. The proposed architecture is being used during feasibility studies on advanced networking technologies for the CMS experiment at CERN. The design relies on a homogeneous peer-to-peer message passing system, which is built around memory pool caches allowing efficient and deterministic latency handling of messages of any size through the different software layers. In this scheme portable distributed applications can be programmed to process input to output operations by mere pointer arithmetic and DMA operations only. The approach combined with the open fabric protocol stack (OFED) allows one to attain near wire-speed message transfer at application level. The architecture supports full portability of user applications by encapsulating the protocol details and network into modular peer transport services whereas a transparent replacement of the underlying protocol facilitates deployment of several network technologies like Gigabit Ethernet, Myrinet, Infiniband etc. Therefore, this solution provides a protocol-independent communication framework and prevents having to deal with potentially difficult couplings when the underlying communication infrastructure is changed. We demonstrate the feasibility of this approach by giving efficiency and performance measurements of the software in the context of the CMS distributed event building studies.

This study explores some possibilities of social network analysis for studying adolescents’ communication patterns. A full network analysis was conducted on third-grade high school students (15 year olds, 137 students) in Belgium. The results pointed out that face-to-face communication was still the most prominent way for information to flow through the network. Interactions through communication media (e-mail, instant messaging, text messaging, mobile phone, and landline phone), however, supplemented this flow of information in a substantive way. Communication media use patterns were characterized by multiplexity and could be placed on a unidimensional scale indicating a media hierarchy. Close friends (strong ties) used all communication media at their disposal to connect with each other; students who were just friends (weak ties) preferred face-to-face communication and social network sites. In the discussion, some other possibilities of social network analysis for studying adolescents’ communication media are discussed.

There is a lot of talk about the ‘newness’ of mobile and wireless Information and Communication Technologies (ICTs) these days. What is so ‘new’ about them? And in what way will they solve the still unresolved problems of poverty, inequality and information divides in the world? This chapter takes a bird’s eye perspective and presents a number of observations regarding the role of ICTs within the field of Communication for Development and Social Change (CDSC). All those involved in the analysis and application of Communication for Development and Social Change would probably agree that in essence communication for social change is the sharing of knowledge aimed at reaching a consensus for action that takes into account the interests, needs and capacities of all concerned. It is thus a social process, which has as its ultimate objective sustainable development at distinct levels of society. Communication media and Information and Communication Technologies (ICTs) are important tools in achieving social change but their use is not an aim in itself—interpersonal communication and traditional group media must also play a fundamental role. This basic consensus on development communication has been interpreted and applied in different ways throughout the past century. Both at theory and research levels, as well as at the levels of policy and planning-making and implementation, divergent perspectives are on offer. In this chapter, the author presents a brief overview of the field of Communication for Development and Social Change (CDSC) and elaborates on the role and impact of Information and Communication Technologies (ICTs) for Development and Social Change.

Cyberphysical system is the integration of physical space (equipment, devices and people) with computing, communication and control systems (cyberspace). The National Institute of Standards and Terminology (NIST) has defined CFS as cyberphysical systems (CFS), which are designed systems built on the continuous integration of computational algorithms and physical components. Improving the CFS provides greater opportunities for performance, adaptability, scalability, stability, security and usability, far exceeding today's simple embedded systems. CFS technology will transform the interaction of people with the engineering system [1, 2]. Today, cyberphysical systems exist in various fields, such as automotive, aerospace, civil, railway, medical. Large productions seek to increase the availability of the asset, while reducing maintenance costs through cyberphysical systems. With the development of the industry and the use of systems in production, the proposed maintenance is used constantly to avoid failures. CFS maintenance is performed when certain indicators signal that the condition of the system has deteriorated. One way to solve this problem is to provide systems with resistance properties. Such systems are able to recover quickly and continue to function in changing conditions [3-9]. Therefore, the urgent task is to develop approaches that will predict the resilience of cyberphysical systems based on cloud computing. It is necessary to build methods and tools that will monitor the condition of the CFS and predict the timely replacement of their components that may fail. The application of the process of predicting the resilience of cyberphysical systems using cloud-oriented increases the effective reliability and availability of cyberphysical systems in its life cycle by identifying future failures and reducing unscheduled maintenance. The forecasting process involves the assessment of the useful life, and the implementation of a post-forecast decision on maintenance measures in accordance with the rules. The method of predicting the resilience of cloud-oriented cyberphysical systems allows to determine the state of the cyberphysical systems using cloud computing. The mechanism used to reduce the cost of maintenance and detailed planning of maintenance operations, the apparatus of genetic algorithms.

New radio technology suit very well to implement mobile positioning systems, because the future signals are wideband and software radio (SDR) defined platforms are used for implementation. If the used communication system is not sufficient for required positioning purposes, the SDR principle allows that the same platform is used or divided by a positioning system. These positioning systems function anywhere where the underlying communication systems have a sufficient coverage for positioning. Alternatively, a sufficient coverage can be guaranteed locally by establishing a positioning network. These local mobile positioning systems serve as a backup to or as a more robust alternative to global navigation satellite systems that are known to be rather vulnerable to interference. In this paper some design aspects of interference immune local mobile positioning systems are considered. The considered topics include a short introduction to the Finnish Software Defined Radio Programme, which covers both communications and positioning systems in the same platform. Topics considered herein include also positioning network design, delay estimation in frequency hopping systems with few samples and interference mitigation techniques both for single antenna and adaptive antenna receivers.

To estimate the potential to reinforce resilience in a power system under severe power deficit conditions, this study investigates the flexibility of space and water heating systems equipped with heat pumps in approximately one million single-family houses. The main contribution lies in the quantification of available power and corresponding duration of reduced power linked to the thermal comfort consequence of these resilience efforts. In this context, an integrated physics-based model is developed that involves a heat pump with space and water heating systems. For the power system with a dimensioning fault of 1.45 GW, the flexibility levels found range between 2.1 GW and 0.5 GW, at outdoor temperatures ranging between −10 °C and 10 °C respectively. An example result is that the power system can be relieved with 2.1 GW for 5 h and 0.8 GW for the next 12 h, with a consequence of the indoor and water temperatures dropping from 20 °C and 55 °C, to 15 °C and 44 °C, respectively at −10 °C outdoor temperature. Furthermore, the average electric power consumption increases to 2.9 GW during the recovery of indoor temperatures over 24 h. Finally, a modified Nordic-32 bus system with a large share of renewable power installations is proposed. In this system, the role of flexibility is demonstrated in limiting the instantaneous frequency deviation during the loss of a major generation. Thus, this study clearly shows the potential of single-family houses to reinforce resilience for a duration ranging from seconds to several hours. • Power support for disruptive grid events using flexibility from heat pumps. • Utilisation of physics based models for estimation of flexibility potential. • Flexibility quantification from space and water heating in about a million houses. • Flexibility potential for various time periods. • Flexibility potential range is 2.1-0.5 GW, at temperatures ranging from −10 °C to 10 °C.

The rapid growth of wireless communication systems and devices has increased global energy consumption in wireless communication networks. Therefore, wireless communication technologies are advancing towards the development of fifth-generation wireless communication systems and beyond, i.e., towards the development of sixth-generation wireless communication systems. It is important that the energy efficiency of wireless communication systems considered a significant parameter along with data rate, delay and reliability. Green wireless communication systems aim to reduce the power consumption of wireless communication systems minimize carbon emissions and make wireless communication systems environmentally sustainable. This paper presents a comprehensive review of sustainable wireless communication systems and energy-efficient protocols for green wireless communication systems. This study discusses various architectural strategies such as energy-efficient base stations, heterogeneous and ultra-dense networks, cloud radio access networks, adaptive networks, renewable energy and their role enables wireless networks to modify their behavior according to the nature of the data and availability of resources. Further, the paper discusses the role of sustainable wireless protocols in all layers of wireless communication, where techniques like power control, duty cycle, energy-efficient routing and transport protocols are playing a significant role in removing the unnecessary communication and utilizing resources efficiently. It also discusses enabling technologies that can be utilized in energy-efficient network operation including energy harvesting, cognitive radio, artificial intelligence, edge computing and network virtualization. Moreover, some of the major challenges in energy-efficient wireless communication including decisions, complexity, security, cost, and regulatory issues, are addressed. This study provides an sustainable wireless communication can be achieved based on recent developments and existing research gaps in wireless communication particularly in future 5G and 6G networks.

Networked control systems offer significant advantages in terms of reliability, commissioning and maintenance, especially for complex systems. They must be able to withstand delays and data corruption caused by the underlying communication network. Existing results in networked control systems provide varying degrees of robustness. However, cost is also an important factor for real world implementations, which further restricts the bandwidth of the underlying network and complexity of the communication protocol. In this paper we introduce a networked control system method, WMBPNCS, that we have previously proposed, and implement a control system using IEEE 802.15.4 (ZigBee) as its communication protocol, in an attempt to overcome these problems. We find through simulations that performance of our implementation is acceptable even under large amounts of random network delay and data loss.

Background: SNOMED CT is a large terminology system designed to represent all aspects of healthcare. Its current form and content result from decades of bottom-up evolution. Due to SNOMED CT’s formal descriptions, it can be considered an ontology. The Basic Formal Ontology (BFO) is a foundational ontology that proposes a small set of disjoint, hierarchically ordered classes, supported by relations and axioms. In contrast, as a typical top-down endeavor, BFO was designed as a foundational framework for domain ontologies in the natural sciences and related disciplines. Whereas it is mostly assumed that domain ontologies should be created as extensions of foundational ontologies, a post-hoc harmonization of consolidated domain ontologies in use, such as SNOMED CT, is known to be challenging. Methods: We explored the feasibility of harmonizing SNOMED CT with BFO, with a focus on the SNOMED CT Clinical Finding hierarchy. With more than 100,000 classes, it accounts for about one third of SNOMED CT’s content. In particular, we represented typical SNOMED CT finding/disorder concepts using description logics under BFO. Three representational patterns were created and the logical entailments analyzed. Results: Under a first scrutiny, the clinical intuition that diseases, disorders, signs and symptoms form a homogeneous ontological upper-level class appeared incompatible with BFO’s upper-level distinction into continuants and occurrents. The Clinical finding class seemed to be an umbrella for all kinds of entities of clinical interest, such as material entities, processes, states, dispositions, and qualities. This suggests the conclusion that Clinical finding would not be a suitable upper-level class from an BFO perspective. On closer inspection of the taxonomic links within this hierarchy and the implicit meaning derived thereof, it became clear that Clinical finding classes do not characterize the entity (e.g. a fracture, allergy, tumor, pain, hemorrhage, seizure, fever) in a literal sense but rather the condition of a patient having that fracture, allergy, pain etc. This gives sense to the current characteristic of the Clinical Finding hierarchy, in which complex classes are modeled as subclasses of their constituents. Most of these taxonomic links are inferred, as the consequence of the ‘role group’ design pattern, which is ubiquitous in SNOMED CT and has often been subject of controversy regarding its semantics. Conclusion: Our analyses resulted in the proposal of (i) equating SNOMED CT’s ‘role group’ property with the reflexive and transitive BFO relation ‘has occurrent part’; and (ii) reinterpreting Clinical Findings as Clinical Occurrents, i.e. temporally extended entities in an organism, having one or more occurrents as temporal parts that occur in continuants. This re-interpretation was corroborated by a manual analysis of classes under Clinical Finding, as well as the identification of similar modeling patterns in other ontologies. As a result, SNOMED CT does not require any content redesign to establish compatibility with BFO, apart from this re-interpretation, and a suggested re-labeling. Regarding the feasibility of harmonizing terminologies with principled foundational ontologies post-hoc, our results provide support to the assumption that this does not necessarily require major redesign efforts, but rather a careful analysis of the implicit assumptions of terminology curators and users.

Information Integrity(I*I) i.e. Accuracy, Consistency and Reliability of information is a fundamental requirement for strategic business advantage in complex and changing environment characterized by uncertainty. However, its implementation is a highly complex and costly activity. Software modeling and development techniques have by and large advocated divide and conquer as the typical approach to handle large and complex business systems. Object oriented modeling has been a major step towards building of large, flexible and evolving systems. Efforts and contributions to support flexibility have been made by database and programming language providers. The same can be witnessed if we trace down the evolution of databases and programming languages both now focusing on extensible and reusable patterns and components as main contributors to providing flexibility in otherwise statically designed software. Software patterns offer another area that has contributed significantly towards designing software with reasonable strengths and known weaknesses. Literature as well as practice has shown evidence of using design patterns, software patterns and business patterns for improved software quality. However, major focus of software and design patterns is still to meet functional and non-functional requirements of a software, whereas business patterns are largely implemented in a manual form. This paper adopts UML to define a framework built on I*I patterns that can be reused by system designers towards building systems that support I*I and its analysis. This paper is an attempt to further the knowledge area of I*I towards a way of implementing it in any size of software project thus reducing complexity as well as the cost of its implementation. Focus of the paper is not to offer a complete suite of I*I patterns but establish a guideline towards building one of such kind.

2. INTRODUCTION The context of this report is a project aimed at reengineering a large and high-entropy air defense system into a modern software architecture for achieving improved performance and better maintainability. A secondary objective of the project was to discover and create a set of reusable software components for use in future air defense projects[1,2]. This paper describes our experience in accomplishing this task. In implementing these components we used several design patterns [3] and took full advantage of the object-oriented features of Ada-95 [4]. All diagrams in this paper are in the Unified Modeling Language (UML) [5] notation.