The software quality challenges of service oriented architectures in e-commerce

Web Services technologies and their supporting collection of de facto standards are now reaching the point of maturity where they are appearing in production software systems. Service Oriented Architectures (SOAs) using Web Services as an enabling technology are also being discussed widely in the IT press. However, despite the numerous and real advantages of these architectural patterns there are still many software quality challenges that remain unresolved. This is particularly true as we consider more advanced architectures that exploit the technology to its maximum advantage: utility computing and on-demand service discovery and composition, grid computing and multi-agent systems will only become pervasive once the software quality challenges of real-world industrial applications have been addressed. In this paper potential quality issues such as performance, reliability and availability are addressed in terms of the quality assurances that might need to be provided to consumers of services. Proposed XML-based Service Level Agreement (SLA) languages are reviewed as a means of providing these quality assurances in machine-readable ways. We also discuss how SLAs might be automatically negotiated to enable automated, on-demand service discovery and composition. The next section of this paper addresses quality issues from a service provider's perspective. The providers of such services will need to ensure that SLA commitments are met and this poses interesting problems in terms of application management. Network quality of service is currently addressed through such means as IntServ and DiffServ. Research proposals to introduce similar techniques at an application level are described. From the service consumer's perspective, interesting research proposals for proactively ensuring that good quality of service is obtained are also reviewed. These could be particularly important for creating confidence, from a consumer's perspective, in these architectures. Finally, the paper evaluates the challenges and suggests areas where further research is most urgently required. Shelly Saunders MSc, BSc (Hons), MBCS (CITP) is an e-commerce Technical Architect, currently employed by ACE Group, a global insurance and reinsurance company. She is also studying part-time for a PhD with the Southampton Institute. She has 12 years experience in the software development industry and has provided the architecture for numerous e-commerce sites for global blue-chip clients. She also has another 5 years experience as a research scientist in the optical communications industry. She holds three patents. Margaret Ross is Professor of Software Quality at Southampton Solent University, She is an active member of the BCS, being on various Boards, Committees, and Working Parties including the BCS Council, the Quality Specialist Group (Vice Chair and Secretary); BCSWomen Specialist Group (Committee member) and the BCS Ethics Expert Panel. She is a Fellow of the BCS and also a Chartered Engineer and Chartered Scientist. Geoff Staples is the Chairman of the BCS Quality Specialist Group and a member of the BCS TickIT Committee. Geoff has been active in various aspects of computing, particularly quality. Geoff has been the Conference Chair or for the BCS Quality Specialist Groups international SQM and INSPIRE conferences are for many years. He is a Fellow of the BCS and Fellow of the Royal Statistical Society and also a Chartered Engineer Sean Wellington leads the Communications Engineering Subject Group (CESG) within the Faculty of Technology at Southampton Solent University. The group is responsible for programmes in computer systems and networks, web design, media technology and electronic engineering. Sean has a wide range of academic and research interests, including digital signal processing and multisensor fusion. He is an active member of the Institution of Electrical Engineering (Member 1993, Fellow 2002) and has served on numerous boards and committees.     

Reengineering for service oriented architectures: A strategic decision model for integration versus migration

Service Oriented Architecture (SOA) is a popular paradigm at present because it provides a standards-based conceptual framework for flexible and adaptable enterprise wide systems. This implies that most present systems need to be reengineered to become SOA compliant. However, SOA reengineering projects raise serious strategic as well as technical questions that require management oversight. This paper, based on practical experience with SOA projects, presents a decision model for SOA reengineering projects that combines strategic and technical factors with cost-benefit analysis for integration versus migration decisions. The paper identifies the key issues that need to be addressed in enterprise application reengineering projects for SOA, examines the strategic alternatives, explains how the alternatives can be evaluated based on architectural and cost-benefit considerations and illustrates the main ideas through a detailed case study.     

Visual understanding industrial workflows under uncertainty on distributed service oriented architectures

Service Oriented Architecture (SOA) is an evolution of distributed computing based on the request/reply design paradigm for synchronous and asynchronous applications. In such architectures, application developers or system integrators can build scenarios by composing one or more services without knowing the services’ underlying implementations. In this paper, we adopt a SOA framework for on-line scheduling complex industrial workflows. The proposed SOA consists of three main layers; the input layer, the benchmarking layer, the prediction layer and the scheduler. The main innovation of our SOA architecture is the prediction layer that supports computer vision tools able to visually observe how an industrial workflow is actually executed. This way, we can automatically estimate the actual execution time for a process. In particular a new self-initialized visual tracker algorithm is proposed in this paper to robustly trace workers’ trajectory in a plant via visual observations. Then, part-to-whole curve matching is presented so as to find correspondences among the traced curve and the ideal one and thus improving scheduler efficiency. The input layer interoperably describes industrial operations using the XPDL (an XML-based) format. The benchmarker evaluates much faster than real-time and in an off-line mode how long it takes for an industrial workflow to be executed on a given resource guaranteeing an almost real-time implementation of the video processing algorithms on the plant. The last component of the proposed SOA is the scheduler with the goal to assign the workflows to the available resources. In this paper, a Maximum Benefit First (MBF) scheduler is presented which maximizes the total gain received by the industry when completing execution of all the beneficial operations with minimum violations of their delivery deadlines (that is with the minimum compensations). Experiments have been conducted on a real-world industrial plant of Nissan Iberica automobile construction indicating the efficiency of the proposed system.     

Enterprise cloud service architectures

As a new computing paradigm, cloud computing has received a lot of attention from enterprises and has being integrated or applied to enterprise architectures. This paper surveys the state of the art of enterprise cloud service architectures. Specifically, this paper discusses enterprise cloud service architectural requirements, design approaches, architectural styles, emerging cloud service platforms, applications and related challenges in an enterprise context. This paper also identifies research trends and opportunities for researchers and practitioners in this fast moving field.     

OpenMP‐oriented applications for distributed shared memory architectures

The rapid rise of OpenMP as the preferred parallel programming paradigm for small‐to‐medium scale parallelism could slow unless OpenMP can show capabilities for becoming the model‐of‐choice for large scale high‐performance parallel computing in the coming decade. The main stumbling block for the adaptation of OpenMP to distributed shared memory (DSM) machines, which are based on architectures like cc‐NUMA, stems from the lack of capabilities for data placement among processors and threads for achieving data locality. The absence of such a mechanism causes remote memory accesses and inefficient cache memory use, both of which lead to poor performance. This paper presents a simple software programming approach called copy‐inside–copy‐back (CC) that exploits the data privatization mechanism of OpenMP for data placement and replacement. This technique enables one to distribute data manually without taking away control and flexibility from the programmer and is thus an alternative to the automat and implicit approaches. Moreover, the CC approach improves on the OpenMP‐SPMD style of programming that makes the development process of an OpenMP application more structured and simpler. The CC technique was tested and analyzed using the NAS Parallel Benchmarks on SGI Origin 2000 multiprocessor machines. This study shows that OpenMP improves performance of coarse‐grained parallelism, although a fast copy mechanism is essential. Copyright © 2004 John Wiley & Sons, Ltd.     

一种面向Web服务的分级服务模型*

以服务响应时间为QoS参数,提出了一种面向Web服务的分级QoS方法,该方法从预测请求响应时间入手,通过区分操作类型并采用优先级队列调度策略,进而保证请求响应时间.在ONCE平台内置SOAP引擎SOAPExpress的基础上进行了原型实现.实验表明,该方法能有效地保证不同级别用户的请求响应时间,实现服务分级.     

A reference requirements set for public service provision enterprise architectures

Electronic Government (eGov) is a political priority worldwide. One of the core objectives of eGov is the online public services provision (PSP). However, many of eGov PSP systems fail in realizing their objectives. Enterprise Architectures (EA) could contribute to overcome some of the relevant obstacles. The objective of this paper is to derive a reference requirements set for eGov PSP that can be used in EA development. Aiming at capitalizing on existing knowledge, we conduct a systematic literature review on eGov PSP systems requirements. This results in identifying a unified requirements set, i.e. 186 requirements, and stakeholders set, i.e. 19 stakeholders, for eGov PSP systems. Based on these findings, we determine 16 overview use cases demonstrating the basic functionality of such systems. Our findings are modeled using ArchiMate 2.0 notation. The identified requirements set can be used by virtually any public organization providing public services for developing its own EA. As a result, it can lead to the reduction of eGov PSP project failures, the decrease of software development costs and the improvement of its effectiveness and quality. Furthermore, it can be used as a basis to develop a complete reference EA for the eGov PSP domain.     

Linking market uncertainty to VoIP service architectures

The flexibility of packet-switching technologies, coupled with the economic benefits of sending voice over IP networks, is accelerating the convergence of data and voice. It remains unclear, however, which voice-over-IP (VoIP) architecture will best meet user needs, which services will be most successful, and where in the network these services should reside. The question of where to place services in IP telephone networks depends on many variables, including the end systems' capabilities, the amount of interaction the service requires with the end user, and the network infrastructure's architecture. The limited ability of dumb end devices, such as the telephones in the public switched telephone network (PSTN), force service providers to implement services within the network. Smart end systems allow providers more choice in where to locate services. This article describes the main architectural options for VOW and discusses their associated economic effects. By focusing on the relationship between architecture and market uncertainty, the author demonstrates how high uncertainty enhances the value of architectures that allow distributed network services.     

面向服务簇的服务流程构建

为了减少服务流程的构建时间,优化流程的服务质量,增强流程响应自适应性,提出一种面向服务簇的流程构建方法。采用服务簇作为组成服务流程的基本单位,将服务流程的构建划分为面向簇的流程服务推荐和最优服务流程质量计算两个阶段,并给出具体实现方案。仿真实验以10000个Web服务和不同的流程模式作为测试源,与面向原子服务组建的服务流程相比,面向簇构建服务流程及服务失效时的流程重构时间均至少降低50%,而构建的服务流程质量至少提高10%。仿真结果表明该方法可以有效缩减流程组建时间,提高构建流程的服务质量,增强流程响应自适应性。     

Viewpoints of DSP software and service architectures

The software architecture of a future mobile telecommunication system consists of three main parts: system infrastructure services, middleware services and application services. Infrastructure services provide access technologies and networking services for the middleware services that again provide richer capabilities for wireless applications through mobile Internet. Architecture describes the organization of software systems, components, their internal relationships and connections to the environment. Reusing architectural structures benefits companies, because the architecture is a pivotal part of any system, and a costly one to construct. Architecture is documented and reused through architectural views that describe identified stakeholders and concerns, e.g. the purpose of a system, and the feasibility of constructing, deploying, evolving and maintaining it. Views conform to special viewpoints defined for the domain. This paper describes the viewpoints selected for developing the architecture of middleware services and digital signal processing software and provides a general framework for comparing viewpoints. Comparison and analysis of the defined viewpoints show that domain and system size are the dominant issues to be considered when architectural viewpoints are being selected.     

Service oriented architectures: approaches,technologies and research issues

Service-oriented architectures (SOA) is an emerging approach that addresses the requirements of loosely coupled, standards-based, and protocol- independent distributed computing. Typically business operations running in an SOA comprise a number of invocations of these different components, often in an event-driven or asynchronous fashion that reflects the underlying business process needs. To build an SOA a highly distributable communications and integration backbone is required. This functionality is provided by the Enterprise Service Bus (ESB) that is an integration platform that utilizes Web services standards to support a wide variety of communications patterns over multiple transport protocols and deliver value-added capabilities for SOA applications. This paper reviews technologies and approaches that unify the principles and concepts of SOA with those of event-based programing. The paper also focuses on the ESB and describes a range of functions that are designed to offer a manageable, standards-based SOA backbone that extends middleware functionality throughout by connecting heterogeneous components and systems and offers integration services. Finally, the paper proposes an approach to extend the conventional SOA to cater for essential ESB requirements that include capabilities such as service orchestration, “intelligent” routing, provisioning, integrity and security of message as well as service management. The layers in this extended SOA, in short xSOA, are used to classify research issues and current research activities.     

面向服务簇的服务体系结构及服务发现

为了缩减服务查找空间,提高服务发现效率,提出服务簇的概念。将具有相似或相同服务功能的Web服务封装为一个服务簇,构建基于服务簇的服务请求/响应模式。给出了服务簇的形式化定义、面向服务簇的服务体系结构以及服务簇模式下的最优服务发现算法。仿真实验以10000个Web服务作为测试源,在服务簇数目不大于1000时,服务簇模式下的服务查找时间以及服务再查找时间均小于600ms,而当前服务响应模式下,上述时间均大于900ms。实验结果表明：基于服务簇的服务请求/响应模式可以显著提高服务发现效率,并能大幅度降低服务再查找的时间。     

一种基于软件定义网络的服务功能链优化部署机制

针对软件定义网络环境下现有服务链部署方法未能充分考虑全网资源利用率的问题,提出了一种基于高效启发式算法的服务链优化部署机制。首先,给出了服务链部署的总体结构,并引入了整数线性规划模型对其进行数学建模;其次,提出了一种高效启发式的模型求解算法,该算法以先排序后贪心的方式,能够在满足资源和时延约束下有效利用网络资源和均衡负载。仿真结果表明,与其他部署算法相比,该算法在降低负载均衡度和时间复杂度的同时提高了请求接受率。     

一种面向服务体系结构的服务组合方案求解方法*

面向服务体系结构的出现为分布式应用集成提供了一种解决方案,如何快速准确地指定具体服务或求解出服务的组合方案的问题尚待解决。根据对抽象服务的输入/输出等功能性属性的描述,完成了抽象服务组合流程建模,为了对抽象层粗粒度服务的求精,提出了一种基于语义Web服务和图规划技术的服务自动组合机制,该方法将Web服务映射为规划动作的形式化描述,形式化推理得出Web服务的组合方案。在具体的服务或方案选择上,利用服务相似度优化服务或服务组合方案的选取。最后通过模拟实验验证了该方法的有效性。     

End-to-end reliability of service oriented applications

As organizations move towards adopting a service oriented architecture that permits the coexistence of multiple technology environments, an increasing number of applications will be developed through the assembly of existing software components with standard web service interfaces. These components with web service interfaces may be available in-house, or may be supplied or hosted by external vendors. The use of multiple services, possibly utilizing different technologies, providers, locations, and sources, has implications for the end-to-end reliability of these applications to support a business process. Selecting the best service for individual tasks in a business process does not guarantee the most effective overall solution, particularly if criteria other than functional characteristics are employed. This paper examines reliability issues associated with applications developed within service oriented architecture. It develops a measure for deriving end-to-end application reliability, and develops a model to help select appropriate services for tasks in the business process which accommodate the redundant and overlapping functionality of available services and planned redundancy in task support to satisfy the reliability requirement of the resulting application. A genetic algorithm approach is adopted to select promising services to assemble the application using end-to-end reliability as the criterion of interest. An application to a real-world business process illustrates the effectiveness of the approach.     

Evaluation models for service oriented process in spare parts management

Maintenance, repair, operation (MRO) and spare parts supply is a critical issue for expensive repairable items such as cutting tool in the metal cutting industry. A new type of servicization model in the cutting tool supply chain reveals that most research has focused on local optimization of operational issues such as tool monitoring, spare parts management, logistics, and scheduling problems in isolation. The innovation in technologies, such as radio frequency identification and web services, for information sharing provides the ability to plan and schedule the tool requirement cross different layers in the MRO supply chain. However, their impact on the, technology complexity and performance is uncertain. In order to provide evaluation approach at the design phase, this paper analyzes the service oriented process from two dimensions that evaluate technology complexity, and system performance. Implementation of these evaluation models helps organizations analyze the business processes and further improve them through the analysis.     

Self-scalable services in service oriented software for cost-effective data farming

Software maintenance is one of the major concerns in service oriented ecosystem with an ever-increasing importance. In many cases, the cost of software maintenance is higher than the cost of software development. In particular, long-lasting services, which operate in a dynamically changing environment, require continuous management and administration. One of the important administration actions is scaling management. The problem lies in responding to workload changes of the hosted services as fast as possible. This is especially important in regard to (but not limited to) cloud environments where unnecessary resource usage leads to unnecessary costs. In this paper, we are introducing the self-scalable services and scaling rules, which are intended to support development of self-scalable systems based on Service Oriented Architecture. We propose a design of a self-scalable service based on some of the well-known software development practices along with a definition of scaling rules, which express scaling policy for the service. Both concepts were evaluated in the context of a massively scalable platform for data farming. The evaluation demonstrates advantages of utilizing the proposed concepts to manage the platform in comparison with traditional platform management strategies based on fulfilling peak load.     

Ontological map of service oriented architecture for shared services management

Service oriented architecture (SOA) and shared services (SS) have been widely studied in the information technology literature. However, there is a lack of tools for shared services management (SSM) to apply SOA. This paper proposes an ontological map for SSM to apply SOA. This mapping approach, based on the well-known Zachman framework of information architecture, specifies the ontological perspective of SOA for SSM. The ontological map semantically links all aspects of SOA for SSM. Through a case study, a design artifact of computerized ontological map of SOA demonstrates the usability of the artifact for SSM.