Self-adaptive software with decentralised control loops explained

On patterns for decentralized control in selfadaptive systems. Also, little is known about the stability of systems built this way and more work remains to be done in this area. All living organisms have a highly developed capacity for adaptation. We present decide, a rigorous approach to decentralising the control loops of distributed selfadaptive software used in mission. Toward self adaptive software employing model predictive control nii shonan meeting on controlled adaptation of self adaptive systems casas shonan, japan, april 2428, 2016. In a large scale distributed system a centralized approach proves infeasible due to issues of scalability as well as the controller being a. Thechoicesdependonthe structure of the system and the complexity of the adaptation goals. The mapek monitoranalyzeplanexecute over a shared knowledge feedback loop is the most influential reference control model for autonomic and selfadaptive systems. Formal design and verification of selfadaptive systems with. A conflict resolution control architecture for selfadaptive. Meng 8 proposed a control system for self adaptive software based on a descriptive model of a self adaptive control system, which employs the. Decide decentralised control in distributed selfadaptive software. Moos provides a core autonomy middleware capability and the moos project additionally provides a set of ubiquitous infrastructure utilities.

On patterns for decentralized control in selfadaptive systems, software engineering for selfadaptive systems ii, lncs vol. Holvoet, architecturecentric support for adaptive service collaborations, acm transactions on software engineering and methodology 231. Modeldriven engineering of selfadaptive software with. One prominent approach for organizing a control loop in selfadaptive systems is by means of four components that are responsible for the primary functions of selfadaptation. Lncs 7475 software engineering for selfadaptive systems. Control theory is an established formal discipline typically used to control the behavior of physical systems, such as production lines, aircrafts, etc. Selfadaptive software evaluates its own behavior and changes behavior when the evaluation indicates that it is not accomplishing what the software is intended to do, or when better functionality or performance is possible. Find out more on the decide website, watch the demo below, or read.

As in 36, with decentralization, we refer to how control decisions in a selfadaptive software system are coordinated among different components, regardless of how those control. Citeseerx document details isaac councill, lee giles, pradeep teregowda. Darpa board agency in 1997 as selfadaptive software. Feedback control loop an overview sciencedirect topics. Selfadaptive software needs quantitative veri cation at runtime. According to this article, the essence of selfadaptive software is aligned with. Weyns, in managing tradeoffs in adaptable software architectures, 2017. Decentralization of control typically increases both the importance and the complexity of coordination in the application 11.

A exemplar can be quite generic such as an artifact or rather specific such as a model problem in self adaptive systems. Z using quantitative analysis to implement autonomic it systems. Selfadaptive software is a response to these demands. This paper complements and extends a previous roadmap on software engineering for selfadaptive. While self adaptive software systems are being adopted in more domains, it is imperative to reformulate, or evolve current methods and tools related to feedback loops. Selfadaptive decentralized monitoring in softwaredefined. Exemplars software engineering for selfadaptive systems. In fact, selfadaptivity is linked to what lehman has discussed on feedback and feedback control in the context of the software process for evolution lehman 1996. Currently a lot of the work on selfadaptive systems focus on centralized control 1. The goal is to provide a repository of examples, challenge problems, and solutions that the software. Control strategies for selfadaptive software systems 24. On interacting control loops in selfadaptive systems.

Feedback control loops 20 from the control theory area have been identified as vital elements in engineering selfadaptive software systems. Modeling and analyzing mapek feedback loops for selfadaptation abstract. Software engineering for selfadaptive systems lecture notes. Control loops can be composed in series, parallel, multilevel hierarchical, nested, or independent patterns. A control strategies for selfadaptive software systems. Modeling and analyzing mapek feedback loops for self. Constituent parts of a self adaptive software system to support adaptations, the managed subsystem has to provide support for. From the set of studies identified in stage 1, the first author has extracted the approaches supporting the engineering of collaborative andor decentralized sass control loops i. The software defined networking sdn paradigm can allow network management solutions to automatically and frequently reconfigure network resources. To deal with these uncertainties, a selfadaptive system continuously monitors. Aspects of uncertainty include changing systems goals, changing resource availability and dynamic operating conditions. This paper is about tools for the development and maintenance of selfadaptive software. We present decide, a rigorous approach to decentralising the control loops of distributed self adaptive software used in missioncritical applications.

Villegas1,2 engineering adaptive software systems nii shonan meeting seminar 027 eassy 20 shonan village center, japan september 912, 20 1department of ict, icesi university, cali, colombia 2department of computer science, university of victoria, canada. Selfadaptive software with decentralised control loops. When developing sdnbased management architectures, it is of paramount importance to design a monitoring system that. Pdf on interacting control loops in selfadaptive systems. It is also valuable for image6,7 and signal processing applications. Monitor, analyze, plan, and execute, together forming a mape loop. Introduction the majority of the existing work in the literature agrees 1 2 that self adaptivity in software systems is the ability of a software system to adjust its behaviour during run time to handle. A controller synthesis tool for mdps with multiple meanpayoff objectives tb, kc, vf, ak, pp. Steps in the design and development of a controlbased mechanism for selfadaptive systems.

International seminar, dagstuhl castle, germany, october 2429, 2010 revised selected and invited papers, springer, 20, p. Control strategies for selfadaptive software systems. On patterns for decentralized control in self adaptive systems 79 fig. Design patterns for self adaptive systems engineering. The authors in 43 use core function to refer to the man. Decide is a rigorous approach to decentralising the control loops of distributed selfadaptive software used in missioncritical applications. Selfadaptive system an overview sciencedirect topics.

Self adaptive system an automatic control system that preserves its operational capability under conditions of unforeseen change in the properties of the controlled system, in. It differs from the centralized control system wherein a single controller at central location handles the control function, but in dcs each process element or machine. We continue to apply the self adaptive apporach to resource rich, perceptually enabled environments, such as the mit intelligent room 5, including resource management 8 and face recognition 7. Control loops in selfadaptive systems are typically conceived as a sequence of four computations. Control loops in self adaptive systems are typically conceived as a sequence of four computations. These changes may stem from the software systems self internal causes, e. An adaptive control system is a control system containing a controller which can use the information it gathers online to change itself and improve its performance. Pdf selfadaptive software with decentralised control loops. A conflict resolution control architecture for self adaptive.

Selfadaptive software is generally considered as one of the most promising ap. Selfadaptive software is a very active field of research. Selfadaptive system article about selfadaptive system by. Building selfadaptive software systems costeffectively and in a predictable. Feedback control loops that monitor and adapt managed parts of a software. Motor control systems can help reduce energy consumption and complexity within your facility learn about centralized and decentralized systems, and how they can improve your operations. We present decide, a rigorous approach to decentralising the control loops of distributed selfadaptive software used in missioncritical applications. Self adaptation is typically realized using a control loop. Decentralised control of a quadruple tank plant with a.

One prominent approach for organizing a control loop in self adaptive systems is by means of four components that are responsible for the primary functions of self adaptation. For example, as an aircraft flies, its mass will slowly decrease as a result of fuel consumption. Selfadaptive decentralized monitoring in soft waredefined networks abstract. A scalable architecture for adaptive and distributed. Software engineering for selfadaptive systems the imdea. To reduce the e ect of the interactions, a decoupling network has been added to the output of the controllers. Oneprominent approach for organizing a control loop in selfadaptive. In software engineering for selfadaptive systems ii, pages 76107, 2010. Toward selfadaptive software employing model predictive control.

Adaptive control is the control method used by a controller which must adapt to a controlled system with parameters which vary, or are initially uncertain. Dagstuhl seminars software engineering for selfadaptive. For each topic, we present an overview, suggest future directions, and focus on selected challenges. Many projects also sponsored by the european commission ec have been funded with the goal of providing techniques and tools for selfadaptive and autonomous programs.

Pdf control loops in selfadaptive systems are typically conceived as a sequence of. In the illustrative case study there are no dependencies since there is a single goal. We argue a selfadaptive systems behaviour needs to be explained in terms of satisfaction of its requirements. Moosivp is comprised of two opensource software projects.

This paper considers the development of control architecture for selfadaptive software, which combines conflict resolution and control strategies to. This includes robotics1, manufacturing plants, avionics, vehicle control 3, sensor systems5, and others. Self adaptive system s, decentralized control loops, machine learning, requirements. The self controlling software model supports three levels of control. In 2015 ieee international conference on cyber technology in automation, control, and intelligent systems cyber, pages 2530, june 2015. A dcs is used for continuous, complex controls, have an integrated control center much like a scada, which is the core of the system versus the. Decentralized control is crucial for quality re quirements such as resilience, robustness, and scalability.

Engineering selfadaptive systems through feedback loops. Although noteworthy successes have been achieved in many do mains, there is a lack of understanding on how to engineer dis tributed selfadaptive software systems in which central control is not possible 2, 4. Timos antonopoulos, paul hunter, shahab raza, and james worrell three variables suffice for realtime logic. The impact of architectural styles on self adaptive. For instance, a robotic software system is often adaptive. This paper presents a conceptual and methodological framework for formal modeling, validating, and. Since selfadaptive system requirements may themselves be emergent, a means needs to be found to explain the current behaviour of the. A clear target is therefore to hybridize concepts and method from control engineering, artificial intelligence, computer science and cybernetics, to be jointly adapted and. Software quality, modeldriven software, self adaptive software systems, casebased reasoning, runtime uncertainty 1.

Selfadaptive systems, decentralized control loops, machine learning, requirements engineering, contextual requirements, requirements adaptation 1. Self adaptive systems artifacts and model problems. This chapter describes the moosivp autonomy software for unmanned marine vehicles and its use in largescale ocean sensing systems. Selfadaptive software withdecentralised control loops radu calinescu1, simos gerasimou1, and alec banks2 1 department of computer science, university of york, uk 2 defence science and technology laboratory, ministry of defence, uk abstract. Feedback control loops have been recognized as vital elements for engineering selfadaptive systems. A foundation for engineering decentralized selfadaptive.

Introduction nowadays, software systems are extremely capable, mimicking natural systems characteristics such as. For example, the feedback loops at every stage in royces waterfall model 18 or the risk feedback loop in boehms spiral model 19 are well known. Control design process this section discusses the design of a control loop for an existing software system. Decide uses quantitative verification at runtime, first to agree individual component contributions to meeting systemlevel qualityofservice requirements, and then to ensure that components. One key challenge is to assure the required quality properties in decentralized. This paper complements and extends a previous roadmap on software engineering for selfadaptive systems published in 2009 covering a di erent set of topics, and re. A selfadaptive software system consists of a managed system and a feedback loop that monitors and adapts a managed system when needed to realize some quality goals. Also, we identify a set of challenges for control of self adaptive software sec. Selfadaptive system an automatic control system that preserves its operational capability under conditions of unforeseen change in the properties of the controlled system, in the control goal, or in the environment by changing its operation algorithm or searching for optimal states. Selfadaptive system article about selfadaptive system. Hence there is a need for these systems to be selfadaptive and manage themselves at runtime. Sep 01, 2014 the proposed adaptation system is designed according to the classical autonomic control loop mape k monitoring, analysis, planning and execution 3, which is the most common approach for self adaptive systems 5, 33.

Decentralized control is crucial for quality re quirements. Selfadaptation can also be explained with reference to autonomic computing 20, which employs a monitoranalyseplanexecute mape closed control loop to achieve selfmanagement within computer systems. The ivp helm is the primary component of an additional set of. Qualityaware approach for engineering self adaptive. Autonomy for unmanned marine vehicles with moosivp. The design of complex distributed selfadaptive systems having decentralized. Self adaptation has been proposed to overcome the complexity of todays software systems which results from the uncertainty issue. That is, multiple control loops have to know the adaptation decisions of one another to work collaboratively. Despite substantial achievements in the field, important challenges remain open for future research. Selfadaptive decentralized monitoring in softwarede.

An outcome of this seminar is the seams 2015 paper software engineering meets control theory openaccess version and its extension control strategies for selfadaptive software systems openaccess version published in acm taas journal in 2017. Selfadaptive software with decentralised control loops rc, sg, ab, pp. During the development of a traffic monitoring system with. Selfadaptation is typically realized using a control loop. Selfadaptive software with decentralised control loops core. As illustrated in figure 3, te supports self control or selfdispatch, usually automated, of generation, load, and storage devices in facilities owned or controlled by parties that receive the benefits and pay the costs of their operation. Decentralized control an overview sciencedirect topics. Automated multiobjective control for selfadaptive software design antonio filieri university of stuttgart stuttgart, germany. Engineering selfadaptive systems through feedback loops 51 feedback loops have been recognized as important factors in software process management and improvement or software evolution. Software engineering for self adaptive systems lecture notes in computer science programming and software engineering lecture notes in computer science 5525 cheng, betty h.

Such control loops are typically organized by means of four components that are responsible for the fundamental functions of selfadaptation. Calinescu, radu, gerasimou, simos, banks, alec, selfadaptive software with decentralised control loops, international conference on fundamental approaches to software engineering, 235. For example, in the rainbow framework 17, the managedsubsystemmaps to the systemlayerand the managingsubsystem to the architecture layer. Pdf we present decide, a rigorous approach to decentralising the control loops of distributed selfadaptive software used in missioncritical. The distinction between adaptive and selfadaptive software lies in the feedback control loop. Designing software systems that have to deal with dynamic operating conditions, such as changing availability of resources and faults that are difficult to predict, is complex.

In addition, the proposed adaptive monitoring method achieves signi. In 23, we have proposed and devised a set of design patterns for modeling the possible different interactions between the components in one feedback control loop as well as components from different control loops. In air defense, the normal mode whereby a higher echelon monitors unit actions, making direct target assignments to units only when necessary to ensure. An increasingly important concern of software engineers is handling uncertainties at design time, such as environment dynamics that may be difficult to predict or requirements tha. The evaluation results provide empirical evidence about the applicability of sacre in real and complex software system domains. A distributed control system dcs is a specially designed automated control system that consists of geographically distributed control elements over the plant or control area. The decentralized selfadaptive systems face more dynamism as multiple control loops need to coordinate continuously. Software from components selfadaptive software systems. Rqv rqv based decentralised control ensures that distributed systems dev eloped using our. The different levels group steps into activities with tighter coupling.

On patterns for decentralized control in selfadaptive. The next step is to analyze the closed loop system and to prove that its behavior. This site contains a set of exemplars for self adaptive systems. Automated multiobjective control for selfadaptive software. Ideally, with this component the quadruple tank plant can be seen as two noninteracting processes, and therefore the two control loops are independent. A controlbased approach for selfadaptive software systems. For example, uls systems embody both topdown and bottomup selfadaptive characteristics e. In this reference model, core to the operation ofthecomponent that. Although noteworthy successes have been achieved in many do mains, there is a lack of understanding on how to engineer dis tributed self adaptive software systems in which central control is not possible 2, 4. Mapek formal templates to rigorously design behaviors for self adaptive systems. It is a decentralized control where each input is paired with one output. Pdf control strategies for selfadaptive software systems. For example, in the rainbow framework 17, monitoring and execution are del. An adaptive software has an external feedback control loop, that is, between the software and the domain environment in which it is deployed.