基于动态匹配网络的制造服务组合自适应方法

云制造（cloud manufacturing,CMfg）模式下,制造任务和制造服务都处于动态变化的环境中,制造服务组合的动态适应能力问题亟待解决.针对这一问题,以制造任务和制造服务的匹配关系为基础,构建了制造任务-制造服务动态匹配网络（dynamic matching network,DMN）理论模型,在此基础上提出了一种三阶段的制造服务组合自适应方法（three-phase manufacturing service composition self-adaptive approach,TPMSCSAA）.第一阶段通过负载队列模型对QoS进行动态评估,以负载和动态QoS为优化目标,将最优制造服务组合问题转化为制造服务网络中最短路径的搜索,实现制造服务的动态调度;第二阶段对不同类型的制造任务和制造服务变更进行实时获取,同步更新制造任务网络和制造服务网络;第三阶段触发动态调度算法,完成动态匹配边的重构.最后,通过对电梯设计服务组合的实验仿真,验证了方法的可行性和有效性.     

Self-adaptation of mobile systems driven by the Common Variability Language

The execution context in which pervasive systems or mobile computing run changes continually. Hence, applications for these systems require support for self-adaptation to the continual context changes. Most of the approaches for self-adaptive systems implement a reconfiguration service that receives as input the list of all possible configurations and the plans to switch between them. In this paper we present an alternative approach for the automatic generation of application configurations and the reconfiguration plans at runtime. With our approach, the generated configurations are optimal as regards different criteria, such as functionality or resource consumption (e.g. battery or memory). This is achieved by: (1) modelling architectural variability at design-time using the Common Variability Language (CVL), and (2) using a genetic algorithm that finds nearly-optimal configurations at run-time using the information provided by the variability model. We also specify a case study and we use it to evaluate our approach, showing that it is efficient and suitable for devices with scarce resources.     

Dynamic web service composition based on OWL-S

Composing existing web services for enterprise applications may enable higher level of reuse. However the composition processes are mostly static and lack of support for runtime redesign. In this paper, we describe our approach to the extension of the OWL-S ontology framework for dynamic web service composition. We raise the level of abstraction and propose an abstract service layer so that web services can be com- posed at the abstract service level instead of the concrete level. Each abstract service is attached with an instance pool including all instances of the abstract service to facilitate fail-over and dynamic compositions.     

Toward effective service composition for real-time SOA-based systems

Many application domains are increasingly leveraging service-oriented architecture (SOA) techniques to facilitate rapid system deployment. Many of these applications are time-critical and, hence, real-time assurance is an essential step in the service composition process. However, there are gaps in existing service composition techniques for real-time systems. First, admission control is an essential technique to assure the time bound for service execution, but most of the service composition techniques for real-time systems do not take admission control into account. A service may be selected for a workflow during the composition phase, but then during the grounding phase, the concrete service may not be able to admit the workload. Thus, the entire composition process may have to be repeated. Second, communication time is an important factor in real-time SOA, but most of the existing works do not consider how to obtain the communication latencies between services during the composition phase. It is clear that maintaining a full table of communication latencies for all pairs of services is infeasible. Obtaining communication latencies between candidate services during the composition phase can also be costly, since many candidate services may not be used for grounding. Thus, some mechanism is needed for estimating the communication latency for composite services. In this paper, we propose a three-phase composition approach to address the above issues. In this approach, we first use a highly efficient but moderately accurate algorithm to eliminate most of the candidate compositions based on estimated communication latencies and assured service response latency. Then, a more accurate timing prediction is performed on a small number of selected compositions in the second phase based on confirmed admission and actual communication latency. In the third phase, specific concrete services are selected for grounding, and admissions are actually performed. The approach is scalable and can effectively achieve service composition for satisfying real-time requirements. Experimental studies show that the three-phase approach does improve the effectiveness and time for service composition in SOA real-time systems. In order to support the new composition approach, it is necessary to effectively specify the needed information. In this paper, we also present the specification model for timing-related information and the extension of OWL-S to support this specification model.     

Autonomic Computing through Reuse of Variability Models at Runtime: The Case of Smart Homes

Our research shows that autonomic behavior can be achieved by leveraging variability models at runtime. In this way, the modeling effort made at design time is not only useful for producing the system but also provides a richer semantic base for autonomic behavior during execution. The use of variability models at runtime brings new opportunities for autonomic capabilities by reutilizing the efforts invested at design time. Our proposed approach has two aspects: reuse of design knowledge to achieve AC and reuse of existing model-management technologies at runtime. We developed the Model-Based Reconfiguration Engine (MoRE) to implement model-management operations. Our research demonstrates the approach's feasibility for smart homes, especially for self-healing and -configuring capabilities.     

A framework for the deployment of adaptable web service compositions

The basic paradigm of service-oriented architectures—publication, discovery, and use—can be interpreted in different ways. Current technologies assume a static and rigid approach: UDDI was conceived with the idea of a centralized repository for service publication and BPEL only supports design–time bindings between the orchestrated workflow and the external services. The trend, however, is towards more flexibility and dynamism. The single centralized repository is being substituted by dedicated repositories that cooperate and exchange information about stored services on demand. Design–time compositions are complemented by mechanisms to allow for the selection and binding of services at runtime. This paper presents the research results of our group in delivering a framework for the deployment of adaptable Web service compositions. The publication infrastructure integrates existing heterogeneous repositories and makes them cooperate for service discovery. The deployment infrastructure supports BPEL-like compositions that can select services dynamically, and also adjust their behavior in response to detected changes and unforeseen events. The framework also provides a monitoring-based validation of running compositions: we provide suitable probes to oversee the execution of deployed compositions. The various parts of the framework are exemplified on a common case study taken from the automotive domain. This research is partially supported by the European IST project SeCSE (Service Centric System Engineering) and the Italian FIRB project ARTDECO (Adaptive infRasTructures for DECentralized Organizations).     

Unifying design and runtime software adaptation using aspect models

Software systems are seen more and more as evolutive systems. At the design phase, software is constantly in adaptation by the building process itself, and at runtime, it can be adapted in response to changing conditions in the executing environment such as location or resources. Adaptation is generally difficult to specify because of its cross-cutting impact on software. This article introduces an approach to unify adaptation at design and at runtime based on Aspect Oriented Modeling. Our approach proposes a unified aspect metamodel and a platform that realizes two different weaving processes to achieve design and runtime adaptations. This approach is used in a Dynamic Software Product Line which derives products that can be configured at design time and adapted at runtime in order to dynamically fit new requirements or resource changes. Such products are implemented using the Service Component Architecture and Java. Finally, we illustrate the use of our approach based on an adaptive e-shopping scenario. The main advantages of this unification are: a clear separation of concerns, the self-contained aspect model that can be weaved during the design and execution, and the platform independence guaranteed by two different types of weaving.     

Unifying design and runtime software adaptation using aspect models

Software systems are seen more and more as evolutive systems. At the design phase, software is constantly in adaptation by the building process itself, and at runtime, it can be adapted in response to changing conditions in the executing environment such as location or resources. Adaptation is generally difficult to specify because of its cross-cutting impact on software. This article introduces an approach to unify adaptation at design and at runtime based on Aspect Oriented Modeling. Our approach proposes a unified aspect metamodel and a platform that realizes two different weaving processes to achieve design and runtime adaptations. This approach is used in a Dynamic Software Product Line which derives products that can be configured at design time and adapted at runtime in order to dynamically fit new requirements or resource changes. Such products are implemented using the Service Component Architecture and Java. Finally, we illustrate the use of our approach based on an adaptive e-shopping scenario. The main advantages of this unification are: a clear separation of concerns, the self-contained aspect model that can be weaved during the design and execution, and the platform independence guaranteed by two different types of weaving.     

A policy enforcement framework for verification and control of service collaboration

This paper proposes a policy enforcement framework to dynamically verify and control the collaboration process in Service-Oriented Architecture (SOA). Dynamic SOA collaboration is different from traditional service collaboration where the workflow is pre-defined at design time while the services used can be discovered at runtime. In dynamic collaboration, both the workflows and services can be determined at runtime. As they will be determined at runtime, many verification activities can be performed at runtime. This paper proposes a dynamic policy enforcement framework that follows the dynamic SOA collaboration process to ensure that various system constraints can be enforced at runtime. The framework includes a policy specification language, a policy completeness and consistency checking, and distributed policy enforcement. Finally, this paper presents the construction of a sample example to illustrate these features with quantitative performance data.     

QoS-aware web services composition using GRASP with Path Relinking

In service oriented scenarios, applications are created by composing atomic services and exposing the resulting added value logic as a service. When several alternative service providers are available for composition, quality of service (QoS) properties such as execution time, cost, or availability are taken into account to make the choice, leading to the creation of QoS-aware composite web services. Finding the set of service providers that result in the best QoS is a NP-hard optimization problem. This paper presents QoS-Gasp, a metaheuristic algorithm for performing QoS-aware web service composition at runtime. QoS-Gasp is an hybrid approach that combines GRASP with Path Relinking. For the evaluation of our approach we compared it with related metaheuristic algorithms found in the literature. Experiments show that when results must be available in seconds, QoS-Gasp improves the results of previous proposals up to 40%. Beside this, QoS-Gasp found better solutions than any of the compared techniques in a 92% of the runs when results must be available in 100 ms; i.e., it provides compositions with a better QoS, implying cost savings, increased availability and reduced execution times for the end-user.     

Towards runtime discovery, selection and composition of semantic services

Service-orientation is gaining momentum in distributed software applications, mainly because it facilitates interoperability and allows application designers to abstract from underlying implementation technologies. Service composition has been acknowledged as a promising approach to create composite services that are capable of supporting service user needs, possibly by personalising the service delivery through the use of context information or user preferences. In this paper we discuss the challenges of automatic service composition, and present DynamiCoS, which is a novel framework that aims at supporting service composition on-demand and at runtime for the benefit of service end-users. We define the DynamiCoS framework based on a service composition life-cycle. Framework mechanisms are introduced to tackle each of the phases and requirements of this life-cycle. Semantic services are used in our framework to enable reasoning on the service requests issued by end-users, making it possible to automate service discovery, selection and composition. We validate our framework with a prototype that we have built in order to experiment with the mechanisms we have designed. The prototype was evaluated in a testing environment using some use case scenarios. The results of our evaluation give evidences of the feasibility of our approach to support runtime service composition. We also show the benefits of semantic-based frameworks for service composition, particularly for end-users who will be able to have more control on the service composition process.     

Self-adapting workflow reconfiguration

Because web services are highly interoperable, they are capable of providing uniform access to underlying technologies, allowing developers to choose between competing services. Workflow languages, such as BPEL, compose and sequence Web service invocations resulting in meaningful, and sometimes, repeated tasks. Their prevalence means there may be multiple Web services that perform the same operation with some better than others depending on the situation. Their potential for being unavailable at critical workflow execution times forces a reliance on such redundant services. One remedy for unavailability and situational awareness constraints is using quality of service factors and user-directed preferences to assign priorities to workflows and services to perform run-time replacement. In this paper we describe a novel approach to self-adapting workflow reconfiguration. We discuss the implementation of our approach embodied by the Next-generation Workflow Toolkit that supports runtime workflow reconfiguration using BPEL with a commercial workflow engine. A key design feature is the decoupling of user-directed changes regarding service priority from the actual workflow execution, allowing NeWT to effectively manage and recover from workflow changes at any time. We evaluate NeWT by comparing the same example across multiple commercial systems that claim reconfiguration capabilities.     

面向环境与需求不确定性的系统自适应决策

软件系统在运行时会与其他软硬件系统、设备和用户发生密切交互.软件运行环境呈现出不稳定的特点,同时软件需求也可能会发生变化.由于难以准确预测和描述软件运行时的环境及需求,两者的变化具有不确定性.为提供持续服务,软件需要通过自适应能力,根据环境和自身的变化来调节其行为.不确定性给软件的自适应过程带来很大挑战.现有相关工作主要关注环境变化给需求带来的影响,以及环境变化时如何调节软件行为来满足固定的需求.这些方法难以处理需求不确定时自适应过程中的变化性和复杂性.针对该问题,提出一种基于模糊控制的自适应决策方法,以应对运行时环境与需求的不确定性.首先通过模糊逻辑建模与规约环境和软件中的变化要素,并构建要素间的推理规则;其次基于前馈-反馈控制结构和模糊控制器设计自适应机制;最后通过模糊推理和遗传算法实现决策求解.不同环境和约束下的自适应结果表明：软件能够通过自适应机制和算法求得优化决策.为验证方法的可行性和有效性,通过一个移动端比特币采矿机案例进行了评估.     

A comprehensive engineering framework for guaranteeing component compatibility

Despite advances in software engineering methods and tools, understanding what software components do and ensuring that they work well together remains difficult. This is chiefly due to the lack of support for specifying component interfaces and software compositions formally. Due to these shortcomings, composed systems are subject to incompatibility errors, and software developers struggle to retrieve and understand relevant reusable entities. Constructs recently added to the Unified Modeling Language (UML) supported by validation tools can detect and solve behavioural incompatibility issues, while integrated support for characterisation using ontological techniques can describe what a component does. This paper presents a comprehensive software engineering framework that supports software composition at design time and runtime with compatibility guarantees. Our main contributions are (a) a model-driven development approach that combines UML modelling and ontology techniques for the specification of component properties, their validation and their transformation to code, (b) a middleware platform that supports component discovery, compatibility checking and deployment. Following the proposed approach gives benefits for software engineering, in particular in settings where multiple stakeholders are involved.     

QoS aggregation for service orchestrations based on workflow pattern rules and MCDM method: evaluation at design time and runtime

Service consumers satisfaction is considered today as one of the main concern to be ensured by service providers, especially with the spread of concurrency and the increase of functionally equivalent services. This satisfaction is closely related to quality of service (QoS) perceived by service consumers. In this context, we propose an approach to determine the satisfaction degree corresponding to the QoS of service-based applications, with regard to service consumers’ QoS expectations. Our approach is based on a preference model, which is built only on the basis of service consumer’s provided information. This preference model is also based on the 2-additive Choquet operator that takes into account preferential dependencies. In this paper, we target both design time and runtime aggregation of QoS of service-based applications.     

The Fractal Nature of Web Services

Conventional wisdom holds that the service-oriented architecture approach is the silver bullet for all IT problems nowadays. According to this view, SOA leads to near-perfect applications in which every function is implemented as a service, and a service can call any other service to implement its functionality. This includes not only services that provide business functionality, but also nonfunctional services for logging, monitoring, data transformation, and so on. Services that exist as independent concepts at design time are implemented as independent execution entities at runtime. Assuming that the conceptual system structure is equally useful during execution is a naive and potentially dangerous mistake. Instead, applying high-performance transaction system design criteria that optimize for runtime properties like performance, throughput, and resiliency should be paramount     

Automated maintenance of service compositions with SLA violation detection and dynamic binding

Web service compositions need to adapt to changes in their constituent web services, in order to maintain functionality and performance. Therefore, service compositions must be able to detect web service failure and performance degradation resulting in the violation of service-level agreements. Automated diagnosis and repair are equally important. However, existing standards and languages for service compositions, such as BPEL, lack constructs for web service monitoring and runtime adaptability, which are pre-requisites for diagnosis and repair. We present a solution for transparent runtime monitoring, as well as automated performance degradation detection, diagnosis, and repair for service compositions expressed as BPEL processes. Our solution uses lightweight monitoring techniques, supports customizable diagnosis and repair strategies, and is compatible with any standards-compliant BPEL engine.     

XrML-RBLicensing approach adapted to the BPEL process of composite web services

Web service orchestration represents an open and standards-based approach for connecting web services together leading to higher level of business processes. Business Process Execution Language (BPEL) engines are designed to handle this orchestration. However, web service compositions into BPEL suffer from several non-functional requirements such as security. To address this problem, we propose in this paper a novel approach that is based on a harmony between the licensing concept offered by eXtensible rights Markup Language (XrML), aspect-oriented programming (AOP), and web service compositions in BPEL. Our proposed approach, based on XrML, offers the ability to associate security licenses with activities offered by the composite web services. It allows to automatically generate BPEL aspects depending on the developed licenses, to separate between crosscutting concerns of the composed web services, and provides an easy way to include and update the non-functional requirements (e.g., security) into a BPEL process. It offers also the ability to validate the licenses, at runtime and without affecting the business logic of this model. To evaluate our approach, we have developed an inventory control system (ICS) sample that is composed of several web services. Case study and performance analysis are presented to demonstrate its feasibility as well.     

Declarative Web services composition using proofs

Over the last decade, Web services composition has become a thriving area of research and development endeavors for application integration and interoperability. Although Web services composition has been heavily investigated, several issues still need to be addressed. In this paper, we mainly discuss two major bottlenecks in the current process of modeling compositions. The first bottleneck is related to the level of expertise required to achieve a composition process. Typical procedural style of modeling, inspired by workflow/business process paradigm, do not provide the required abstractions. Therefore, they fail to support dynamic and self-managed compositions able to adapt to unpredictable changes. The second bottleneck in current service compositions concerns their life cycle and their management, also called their governance. In this context, we propose a declarative proof-based approach to Web service composition. Based on the three stages of pre-composition, abstraction, and composition, our solution provides an easy way to specify functional and non-functional requirements of composite services in a precise and declarative manner. It guides the user through the composition process while allowing detection and recovery of violations at both design and run-time using proofs and planning. Experiment results clearly show the added value of the proof-based solution as a viable strategy to improve the composition process.