Enabling cost-aware and adaptive elasticity of multi-tier cloud applications

Elasticity (on-demand scaling) of applications is one of the most important features of cloud computing. This elasticity is the ability to adaptively scale resources up and down in order to meet varying application demands. To date, most existing scaling techniques can maintain applications’ Quality of Service (QoS) but do not adequately address issues relating to minimizing the costs of using the service. In this paper, we propose an elastic scaling approach that makes use of cost-aware criteria to detect and analyse the bottlenecks within multi-tier cloud-based applications. We present an adaptive scaling algorithm that reduces the costs incurred by users of cloud infrastructure services, allowing them to scale their applications only at bottleneck tiers, and present the design of an intelligent platform that automates the scaling process. Our approach is generic for a wide class of multi-tier applications, and we demonstrate its effectiveness against other approaches by studying the behaviour of an example e-commerce application using a standard workload benchmark.     

Compositional reasoning for weighted Markov decision processes

Weighted Markov decision processes (MDPs) have long been used to model quantitative aspects of systems in the presence of uncertainty. However, much of the literature on such MDPs takes a monolithic approach, by modelling a system as a particular MDP; properties of the system are then inferred by analysis of that particular MDP. In contrast in this paper we develop compositional methods for reasoning about weighted MDPs, as a possible basis for compositional reasoning about their quantitative behaviour. In particular we approach these systems from a process algebraic point of view. For these we define a coinductive simulation-based behavioural preorder which is compositional in the sense that it is preserved by structural operators for constructing weighted MDPs from components.     

A verification environment for bigraphs

We present the BigMC tool for bigraphical reactive systems that may be instantiated as a verification tool for any formalism or domain-specific modelling language encoded as a bigraphical reactive system. We introduce the syntax and use of BigMC, and exemplify its use with two small examples: a textbook “philosophers” example, and an example motivated by a ubiquitous computing application. We give a tractable heuristic with which to approximate interference between reaction rules, and prove this analysis to be safe. We provide a mechanism for state reachability checking of bigraphical reactive systems, based upon properties expressed in terms of matching, and describe a checking algorithm that makes use of the causation heuristic.     

Matching of Bigraphs

We analyze the matching problem for bigraphs. In particular, we present a sound and complete inductive characterization of matching of binding bigraphs. Our results pave the way for a provably correct matching algorithm, as needed for an implementation of bigraphical reactive systems.     

普适环境中上下文感知的带演算的Bigraphs描述

针对普适环境中上下文感知系统的形式化建模问题,讨论了Bigraphs理论的扩展模型———柏拉图图形模型在此问题中的适用性及不足。在此基础上,利用带演算的Bigraphs反应系统对上下文感知系统进行描述,并给出了与柏拉图图形模型之间的比较。     

An efficient resource provisioning approach for analyzing cloud workloads: a metaheuristic-based clustering approach

With the recent advancements in Internet-based computing models, the usage of cloud-based applications to facilitate daily activities is significantly increasing and is expected to grow further. Since the submitted workloads by users to use the cloud-based applications are different in terms of quality of service (QoS) metrics, it requires the analysis and identification of these heterogeneous cloud workloads to provide an efficient resource provisioning solution as one of the challenging issues to be addressed. In this study, we present an efficient resource provisioning solution using metaheuristic-based clustering mechanism to analyze cloud workloads. The proposed workload clustering approach used a combination of the genetic algorithm and fuzzy C-means technique to find similar clusters according to the user’s QoS requirements. Then, we used a gray wolf optimizer technique to make an appropriate scaling decision to provide the cloud resources for serving of cloud workloads. Besides, we design an extended framework to show interaction between users, cloud providers, and resource provisioning broker in the workload clustering process. The simulation results obtained under real workloads indicate that the proposed approach is efficient in terms of CPU utilization, elasticity, and the response time compared with the other approaches.

     

基于嵌套赋类的Bigraph反应系统模型

针对Bigraph反应系统中位置图控制间的嵌套关系问题,提出了一个赋类的Bigraph扩展模型。在利用标签范畴Scat(K)给出嵌套赋类位置图定义的基础上,讨论了嵌套赋类位置图的相关性质,给出了嵌套赋类位置图中RPO的构建、证明,以及同前推出IPO的一致性条件的定义、证明。     

A framework for specifying and verifying the behaviour of open systems

Coding no longer represents the main issue in developing software applications. It is the design and verification of complex software systems that require to be addressed at the architectural level, following methodologies which permit us to clearly identify and design the components of a system, to understand precisely their interactions, and to formally verify the properties of the systems. Moreover, this process is made even more complicated by the advent of the “network-centric” model of computation, where open systems dynamically interact with each other in a highly volatile environment. Many of the techniques traditionally used for closed systems are inadequate in this context.We illustrate how the problem of modeling and verifying behavioural properties of open system is addressed by different research fields and how their results may contribute to a common solution. Building on this, we propose a methodology for modeling and verifying behavioural aspects of open systems. We introduce the IP-calculus, derived from the π-calculas process algebra so as to describe behavioural features of open systems. We define a notion of partial correctness, acceptability, in order to deal with the intrinsic indeterminacy of open systems, and we provide an algorithmic procedure for its effective verification.     

Disturbance decoupled estimation for linear differential-algebraic systems

We study the disturbance decoupled estimation problem for linear differential-algebraic systems which are not necessarily regular. We introduce the notion of partial state observers following a recent approach to observer design motivated by considerations for behavioural systems. In our framework, a partial state observer is itself a differential-algebraic system. We derive a characterisation for the existence of (asymptotic) partial state observers. Exploiting the freedom in the proposed observer design, we derive a solution of the disturbance decoupled estimation problem. The characterisation of solvability is obtained via geometric conditions in terms of the generalised Wong sequences.     

Computer-aided manufacturing systems: Work-psychological aspects and empirical findings from case studies

In this paper, findings from a research project on work-psychological concepts for the design of computer-aided integrated manufacturing systems are presented. The work-psychological point of view is that concepts which focus not only on technical aspects, but also on the design of work organization and the use and development of skills and qualifications not only contribute to humane work conditions but are also associated with economics efficiency. Results gained from 60 small and medium size Swiss companies in the capital-goods industry show that very few companies have holistic manufacturing structures in terms of decentralization, functional integration, work group autonomy and complete and challenging tasks. Furthermore, skills and qualifications are not made use of to their fullest extent in most companies. Although technical support in terms of implementation of computer-aided manufacturing systems and technical integration is noticeably high, economic efficiency could not be exclusively attributed to the implementation of technical systems. The attainment of efficiency goals associated with the implementation of technical systems turned out to be higher in companies pursuing a holistic approach to the design of computer-aided manufacturing systems encompassing technical aspects, organizational design and use and development of skills and qualifications.

Relevance to industry

In many companies, the implementation and utilization of computer-aided manufacturing systems is considered an appropriate means for meeting increased market demand. Yet, a growing body of empirical findings indicates that computer-aided manufacturing systems per se will not guarantee that companies perform successfully. Data gained from case studies indicate that a comprehensive approach directed at the joint consideration and optimization of technical systems, organizational design and qualifications will contribute to a successful implementation of computer-aided manufacturing systems in terms of humane working conditions and economic efficiency. The data can be used for the work-psychologically founded design of computer-aided integrated manufacturing systems.     

Multidimensional behaviours: an algebraic approach to control theory for PDE

This paper gives an overview of the algebraic theory of multidimensional behaviours, and it contains some new aspects as well. Some known results are restated with a new proof. After a short introduction to behavioural systems theory, we briefly describe the mathematical background of the algebraic approach. Then we study structural properties such as autonomy and over-determined systems on the one hand, and controllability and flat systems on the other.     

SYSTEMS PERSPECTIVES IN APPLIED MECHANICS

In this work a General Systems view of Applied Mechanics is presented. First, the main concepts and principles related to systems outlook are reviewed. Then, in the framework of systems thinking, the classical and current developments in thermodynamics are discussed. A section is also devoted to the study of mathematical isomorphisms among various mechanical systems/phenomena. A subsequent part of the work deals with the systems approach to mechanics including comparative study of elementalistic-holistic principles and methodologies together with a system approach to the Hamiltonian mechanics. A later section of the work is devoted to the application of systemic concepts in structural engineering. In this section, a systemic as well as reductionistic interpretation of structural analysis and design aspects is presented. The last section of this work deals with a discussion of instability phenomena in solids and fluids from a systemic viewpoint.     

Cloud security technologies

You may have heard a new term that started making rounds very recently – “cloud-based security”. In this paper we describe past and contemporary security technologies based on the knowledge provided from the servers in the Internet “cloud”. We discuss how cloud-based malware scanners can simbiotically coexist with traditional scanning technologies, what are the advantages and limitations of the new approach. We also touch on the privacy aspects and challenges related to testing (especially comparative testing) of the cloud security solutions.     

Communications-oriented development of component-based vehicular distributed real-time embedded systems

We propose a novel model- and component-based technique to support communications-oriented development of software for vehicular distributed real-time embedded systems. The proposed technique supports modeling of legacy nodes and communication protocols by encapsulating and abstracting the internal implementation details and protocols. It also allows modeling and performing timing analysis of the applications that contain network traffic originating from outside of the system such as vehicle-to-vehicle, vehicle-to-infrastructure, and cloud-based applications. Furthermore, we present a method to extract end-to-end timing models to support end-to-end timing analysis. We also discuss and solve the issues involved during the extraction of these models. As a proof of concept, we implement our technique in the Rubus Component Model which is used for the development of software for vehicular embedded systems by several international companies. We also conduct an application-case study to validate our approach.     

Toward a cloud-based manufacturing execution system for distributed manufacturing

This paper illustrates the needs and challenges for the management of distributed manufacturing in a multi-company supply chain and processes these further as features of new IT systems. Requirements are collected from manufacturing companies and combined with insights from literature in the field of current ERP/MES system drawbacks, advantages, needs and challenges. The findings show that the needs and challenges in data integration inside SME networks are closely related to the limitations of current supply chain solutions. Current ERP-solutions lack extended enterprise support and a shared cloud-based approach. On the other hand, current MES solutions can operate the manufacturing process, but not for distributed manufacturing. As an answer to the requirements, we made a proposal for the core of architecture for next generation of MES solution in this position paper. Moreover, a pilot software tool has been developed to support the needs related to real time, cloud-based, light weight operation.     

An element-based displacement preconditioner for linear elasticity problems

Finite element analysis of problems in structural and geotechnical engineering results in linear systems where the unknowns are displacements and rotations at nodes. Although the solution of these systems can be carried out using either direct or iterative methods, in practice the matrices involved are usually very large and sparse (particularly for 3D problems) so an iterative approach is often advantageous in terms of both computational time and memory requirements. This memory saving can be further enhanced if the method used does not require assembly of the full coefficient matrix during the solution procedure. One disadvantage of iterative methods is the need to apply preconditioning to improve convergence. In this paper, we review a range of established element-based preconditioning methods for linear elastic problems and compare their performance with a new method based on preconditioning with element displacement components. This new method appears to offer a significant improvement in performance.     

Reconstructibility of time-invariant and periodic behavioural systems

In this article, the properties of behavioural reconstructibility and forward-observability for systems over the whole time axis ? are introduced. These properties are characterised in terms of appropriate rank conditions, for the time-invariant case. A comparison is made with the existing results in the behavioural setting as well as in the classical state space framework. In the particular case of a periodic system, it is shown that there exists an equivalence between the reconstructibility of the periodic system and its associated lifted system, which is time-invariant. Furthermore, we prove that, for a classical state space system, state reconstructibility is equivalent to behavioural reconstructibility, regardless of the time varying or time-invariant nature of the system. This allows deriving rank tests for the cases of time-invariant and of periodic systems, rediscovering the already known results for state reconstructibility from an alternative perspective. The obtained results contribute to establishing links between two different settings, thus providing a better insight into the considered systems properties.