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Services Computing, IEEE Transactions on

Issue 2 • Date April-June 2014

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Displaying Results 1 - 15 of 15
  • A Novel Time-Obfuscated Algorithm for Trajectory Privacy Protection

    Page(s): 126 - 139
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (806 KB) |  | HTML iconHTML  

    Location-based services (LBS) which bring so much convenience to our daily life have been intensively studied over the years. Generally, an LBS query processing can be categorized into snapshot and continuous queries which access user location information and return search results to the users. An LBS has full control of the location information, causing user privacy concerns. If an LBS provider has a malicious intention to breach the user privacy by tracking the users' routes to their destinations, it incurs a serious threat. Most existing techniques have addressed privacy protection mainly for snapshot queries. However, providing privacy protection for continuous queries is of importance, since a malicious LBS can easily obtain complete user privacy information by observing a sequence of successive query requests. In this paper, we propose a comprehensive trajectory privacy technique and combine ambient conditions to cloak location information based on the user privacy profile to avoid a malicious LBS reconstructing a user trajectory. We first propose an r-anonymity mechanism which preprocesses a set of similar trajectories R to blur the actual trajectory of a service user. We then combine k-anonymity with s road segments to protect the user's privacy. We introduce a novel time-obfuscated technique which breaks the sequence of the query issuing time for a service user to confuse the LBS so it does not know the user trajectory, by sending a query randomly from a set of locations residing at the different trajectories in R. Despite the randomness incurred from the obfuscation process for providing strong trajectory privacy protection, the experimental results show that our trajectory privacy technique maintains the correctness of the query results at a competitive computational cost. View full abstract»

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  • An Empirical Study of Error Patterns in Industrial Business Process Models

    Page(s): 140 - 153
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB) |  | HTML iconHTML  

    Business processes play an important role in organizations; however, not enough attention is given to analyzing and modeling errors in them. In this paper, we study syntactic and control flow error frequencies in business processes from real industry projects. Our samples come from a number of application domains such as Banking and Capital Markets, Insurance and Healthcare, and Retail. We consider industrial business processes modeled in Business Process Modeling Notation (BPMN) and use graph-theoretic techniques and Petri net-based analyses to detect syntactic and control flow-related errors, respectively. We then use a set of metrics that capture different network characteristics of the models and study the empirical relations between the metrics and process errors. The major results of the empirical investigation are: 1) multiple edges to or from tasks as well as hanging nodes are the predominant forms of syntactic errors, 2) syntactic errors occur frequently in Retail & Logistics domain and significantly less in the Insurance and Healthcare domain, and 3) the probability of error occurrence can be modeled as a function of node size and coefficient of connectivity through a logistic regression model which correctly classified 97.6 percent of the cases. View full abstract»

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  • Commitments to Regulate Social Web Services Operation

    Page(s): 154 - 167
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (663 KB) |  | HTML iconHTML  

    This paper discusses how social Web services are held responsible for the actions they take at run time. Compared to (regular) Web services, social Web services perform different actions, for instance establishing and maintaining networks of contacts and forming with some privileged contacts strong and long lasting collaborative groups. Assessing these actions' outcomes, to avoid any violation, occurs through commitments that the social Web services are required to bind to. Two types of commitments are identified: social commitments that guarantee the proper use of the social networks in which the social Web services sign up, and business commitments that guarantee the proper development of composite Web services in response to users' requests. Detecting commitment violation and action prohibition using monitoring results in imposing sanctions on the “guilty” social Web services and taking corrective actions. A system for commitment management in terms of definition, binding, monitoring, and violation detection is also discussed in this paper. View full abstract»

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  • Comprehensive Explanation of SLA Violations at Runtime

    Page(s): 168 - 183
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2319 KB)  

    Service Level Agreements (SLAs) establish the Quality of Service (QoS) agreed between service-based systems consumers and providers. Since the violation of such SLAs may involve penalties, quality assurance techniques have been developed to supervise the SLAs fulfillment at runtime. However, existing proposals present some drawbacks: 1) the SLAs they support are not expressive enough to model real-world scenarios, 2) they couple the monitoring configuration to a given SLA specification, 3) the explanations of the violations are difficult to understand and even potentially inaccurate, 4) some proposals either do not provide an architecture, or present low cohesion within their elements. In this paper, we propose a comprehensive solution, from a conceptual reference model to its design and implementation, that overcomes these drawbacks. The resulting platform, SALMonADA, receives the SLA agreed between the parties as input and reports timely and comprehensive explanations of SLA violations. SALMonADA performs an automated monitoring configuration and it analyses highly expressive SLAs by means of a constraint satisfaction problems based technique. We have evaluated the impact of SALMonADA over the resulting service consumption time performance. The results are satisfactory enough to consider SALMonADA for SLA supervision because of its low intrusiveness. View full abstract»

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  • Decentralized Enactment of BPEL Processes

    Page(s): 184 - 197
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (988 KB) |  | HTML iconHTML  

    This article presents BPELcube, a framework comprising a scalable architecture and a set of distributed algorithms, which support the decentralized enactment of BPEL processes. In many application domains, BPEL processes are long-running, involve the exchange of voluminous data with external Web services, and are concurrently accessed by large numbers of users. In such context, centralized BPEL process execution engines pose considerable limitations in terms of scalability and performance. To overcome such problems, a scalable hypercube peer-to-peer topology is employed by BPELcube in order to organize an arbitrary number of nodes, which can then collaborate in the decentralized execution and monitoring of BPEL processes. Contrary to traditional clustering approaches, each node does not fully take charge of executing the whole process; rather, it contributes to the overall process execution by running a subset of the process activities and maintaining a subset of the process variables. Hence, the hypercube-based infrastructure acts as a single execution engine, where workload is evenly distributed among the participating nodes in a fine-grained manner. An experimental evaluation of BPELcube and a comparison with centralized and clustered BPEL engine architectures demonstrate that the decentralized approach yields improved process execution times and throughput. View full abstract»

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  • Introducing Replaceability into Web Service Composition

    Page(s): 198 - 209
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (705 KB) |  | HTML iconHTML  

    By discovering and reusing relevant web services, an organization can select and compose those services that most closely meet its business and Quality of Service (QoS) needs. As the number of available web services increases, selecting the best fit services for a given task becomes more challenging. QoS attributes play a significant role in the selection process by directing service composition constraints to a workflow plan that has the best QoS values. Two major problems arise at runtime when undesirable events necessitate the need to reselect services and replan the service bindings. First, if the reselection process consumes additional time, it can impact a temporal QoS constraint. Second, the newly generated composition might not comply with other QoS constraints imposed on the plan. This paper proposes an approach to composing web services that both performs reselection and avoids the violation of QoS constraints after replanning by defining and evaluating a replaceability property. Replaceability factors directly into the algorithm's original service selection process considering all QoS constraints. View full abstract»

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  • Privacy-Enhanced Web Service Composition

    Page(s): 210 - 222
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (856 KB) |  | HTML iconHTML  

    Data as a Service (DaaS) builds on service-oriented technologies to enable fast access to data resources on the Web. However, this paradigm raises several new privacy concerns that traditional privacy models do not handle. In addition, DaaS composition may reveal privacy-sensitive information. In this paper, we propose a formal privacy model in order to extend DaaS descriptions with privacy capabilities. The privacy model allows a service to define a privacy policy and a set of privacy requirements. We also propose a privacy-preserving DaaS composition approach allowing to verify the compatibility between privacy requirements and policies in DaaS composition. We propose a negotiation mechanism that makes it possible to dynamically reconcile the privacy capabilities of services when incompatibilities arise in a composition. We validate the applicability of our proposal through a prototype implementation and a set of experiments. View full abstract»

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  • Reliability-Based Design Optimization for Cloud Migration

    Page(s): 223 - 236
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (726 KB) |  | HTML iconHTML  

    The on-demand use, high scalability, and low maintenance cost nature of cloud computing have attracted more and more enterprises to migrate their legacy applications to the cloud environment. Although the cloud platform itself promises high reliability, ensuring high quality of service is still one of the major concerns, since the enterprise applications are usually complicated and consist of a large number of distributed components. Thus, improving the reliability of an application during cloud migration is a challenging and critical research problem. To address this problem, we propose a reliability-based optimization framework, named ROCloud, to improve the application reliability by fault tolerance. ROCloud includes two ranking algorithms. The first algorithm ranks components for the applications that all their components will be migrated to the cloud. The second algorithm ranks components for hybrid applications that only part of their components are migrated to the cloud. Both algorithms employ the application structure information as well as the historical reliability information for component ranking. Based on the ranking result, optimal fault-tolerant strategy will be selected automatically for the most significant components with respect to their predefined constraints. The experimental results show that by refactoring a small number of error-prone components and tolerating faults of the most significant components, the reliability of the application can be greatly improved. View full abstract»

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  • Satisfiability Analysis of Workflows with Control-Flow Patterns and Authorization Constraints

    Page(s): 237 - 251
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (730 KB) |  | HTML iconHTML  

    Workflow security has become increasingly important and challenging in today's open service world. While much research has been conducted on various security issues of workflow systems, the workflow satisfiability problem, which asks whether a set of users together can complete a workflow, is recently identified as an important research problem that needs more investigation. In this paper, we study the computational complexity of the problem along two directions: one is by considering either one path or all paths of a workflow, and the other is by considering the possible patterns in a workflow. We have shown that the general workflow satisfiability analysis problem is intractable. This result motivates us to consider restrictions on workflow control-flow patterns and access control policies, and to identify tractable cases of practical interest. View full abstract»

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  • Scalable and Accurate Prediction of Availability of Atomic Web Services

    Page(s): 252 - 264
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (665 KB) |  | HTML iconHTML  

    The modern information systems on the Internet are often implemented as composite services built from multiple atomic services. These atomic services have their interfaces publicly available while their inner structure is unknown. The quality of the composite service is dependent on both the availability of each atomic service and their appropriate orchestration. In this paper, we present LUCS, a formal model for predicting the availability of atomic web services that enhances the current state-of-the-art models used in service recommendation systems. LUCS estimates the service availability for an ongoing request by considering its similarity to prior requests according to the following dimensions: the user's and service's geographic location, the service load, and the service's computational requirements. In order to evaluate our model, we conducted experiments on services deployed in different regions of the Amazon cloud. For each service, we varied the geographic origin of its incoming requests as well as the request frequency. The evaluation results suggest that our model significantly improves availability prediction when all of the LUCS input parameters are available, reducing the prediction error by 71 percent compared to the current state-of-the-art. View full abstract»

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  • Service Identification in Interorganizational Process Design

    Page(s): 265 - 278
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1048 KB) |  | HTML iconHTML  

    Service identification is one of the main phases in the design of a service-oriented application. The way in which services are identified may influence the effectiveness of the SOA architecture. More specifically, the granularity of the services is very important in reaching flexibility and reusing them. Such properties are crucial in interorganizational interactions based on collaborative business processes. In fact, collaboration is facilitated by ensuring a homogeneous description of services at the right level of granularity. In this paper, we provide a detailed description of P2S (Process-to-Services), a computer-aided methodology to enable the identification of services that compose a collaborative business process. The methodology is based on metrics defined to setup service granularity, cohesion, coupling, and reuse. A prototype tool based on the methodology is also described with reference to a real case scenario. View full abstract»

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  • Towards Efficient Virtual Appliance Delivery with Minimal Manageable Virtual Appliances

    Page(s): 279 - 292
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (747 KB) |  | HTML iconHTML  

    Infrastructure as a Service systems use virtual appliances to initiate virtual machines. As virtual appliances encapsulate applications and services with their support environment, their delivery is the most expensive task of the virtual machine creation. Virtual appliance delivery is a well-discussed topic in the field of cloud computing. However, for high efficiency, current techniques require the modification of the underlying IaaS systems. To target the wider adoptability of these delivery solutions, this article proposes the concept of minimal manageable virtual appliances (MMVA) that are capable of updating and configuring their virtual machines without the need to modify IaaS systems. To create MMVAs, we propose to reduce manageable virtual appliances until they become MMVAs. This research also reveals a methodology for appliance developers to incorporate MMVAs in their own appliances to enable their efficient delivery and wider adoptability. Finally, the article evaluates the positive effects of MMVAs on an already existing delivery solution: the Automated Virtual appliance creation Service (AVS). Through experimental evaluation, we present that the application of MMVAs not only increases the adoptability of a delivery solution but it also significantly improves its performance in highly dynamic systems. View full abstract»

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  • Variations in Performance and Scalability: An Experimental Study in IaaS Clouds Using Multi-Tier Workloads

    Page(s): 293 - 306
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (757 KB) |  | HTML iconHTML  

    The increasing popularity of clouds drives researchers to find answers to a large variety of new and challenging questions. Through extensive experimental measurements, we show variance in performance and scalability of clouds for two non-trivial scenarios. In the first scenario, we target the public Infrastructure as a Service (IaaS) clouds, and study the case when a multi-tier application is migrated from a traditional datacenter to one of the three IaaS clouds. To validate our findings in the first scenario, we conduct similar study with three private clouds built using three mainstream hypervisors. We used the RUBBoS benchmark application and compared its performance and scalability when hosted in Amazon EC2, Open Cirrus, and Emulab. Our results show that a best-performing configuration in one cloud can become the worst-performing configuration in another cloud. Subsequently, we identified several system level bottlenecks such as high context switching and network driver processing overheads that degraded the performance. We experimentally evaluate concrete alternative approaches as practical solutions to address these problems. We then built the three private clouds using a commercial hypervisor (CVM), Xen, and KVM respectively and evaluated performance characteristics using both RUBBoS and Cloudstone benchmark applications. The three clouds show significant performance variations; for instance, Xen outperforms CVM by 75 percent on the read-write RUBBoS workload and CVM outperforms Xen by over 10 percent on the Cloudstone workload. These observed problems were confirmed at a finer granularity through micro-benchmark experiments that measure component performance directly. View full abstract»

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  • Workload Analysis, Implications, and Optimization on a Production Hadoop Cluster: A Case Study on Taobao

    Page(s): 307 - 321
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1013 KB) |  | HTML iconHTML  

    Understanding the characteristics of MapReduce workloads in a Hadoop cluster is the key to making optimal configuration decisions and improving the system efficiency and throughput. However, workload analysis on a Hadoop cluster, particularly in a large-scale e-commerce production environment, has not been well studied yet. In this paper, we performed a comprehensive workload analysis using the trace collected from a 2000-node Hadoop cluster at Taobao, which is the biggest online e-commerce enterprise in Asia, ranked 10th in the world as reported by Alexa. The results of the workload analysis are representative and generally consistent with the data warehouses for e-commerce web sites, which can help researchers and engineers understand the workload characteristics of Hadoop in their production environments. Based on the observations and implications derived from the trace, we designed a workload generator Ankus, to expedite the performance evaluation and debugging of new mechanisms. Ankus supports synthesizing an e-commerce style MapReduce workload at a low cost. Furthermore, we proposed and implemented a job scheduling algorithm, Fair4S , which is designed to be biased towards small jobs. Small jobs account for the majority of the workload, and most of them require instant and interactive responses, which is an important phenomenon at production Hadoop systems. The inefficiency of Hadoop fair scheduler for handling small jobs motivates us to design the Fair4S, which introduces pool weights and extends job priorities to guarantee the rapid responses for small jobs. Experimental evaluation verified that the Fair4S accelerates the average waiting times of small jobs by a factor of 7 compared with the fair scheduler. View full abstract»

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  • Some Complexity Results for the Soundness Problem of Workflow Nets

    Page(s): 322 - 328
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (353 KB) |  | HTML iconHTML  

    Workflow nets (WF-nets) are widely used to model and verify the business process management systems and composite web services. The (weak) soundness of WF-nets is an important criterion for the correctness of these systems. This paper focuses on the complexity of solving the (weak) soundness problem. Aalst et al. have proven that the (weak) soundness problem is decidable. Our previous work has proven that the soundness problem for bounded WF-nets is PSPACE-complete. This paper shows that the weak soundness problem for bounded WF-nets is also PSPACE-complete. Aalst et al. has proven that the soundness problem is polynomially solvable for free-choice WF-nets (FCWF-nets). This paper discovers that the weak soundness problem is equivalent to the soundness problem for FCWF-nets. Therefore, the weak soundness problem for FCWF-nets is also polynomially solvable. Unfortunately, many composite web services are not modeled by FCWF-nets. Lots of them can be modeled by asymmetric-choice WF-nets (ACWF-nets). This paper proves that the soundness problem is co-NP-hard for ACWF-nets even when they are three-bounded. Additionally, this paper proves that the k-soundness problem is equivalent to the weak soundness problem for WF-nets, which implies that the k-soundness problem for bounded WF-nets is also PSPACE-complete. View full abstract»

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Aims & Scope

The scope covers all computing and software aspects of the science and technology of services innovation research and development. IEEE Transactions on Services Computing emphasizes the algorithmic, mathematical, statistical and computational methods that are central in services computing, the emerging field of Service Oriented Architecture, Web Services, Business Process Integration, Solution Performance Management, Services Operations and Management. Specifically, the transactions covers but is not limited to the following topics: Mathematical foundation of Services Computing, Service-Oriented Architecture (SOA), Service creation, development, and management, Linkage between IT services and business services, Web services security and privacy, Web services agreement and contract, Web services discovery and negotiation, Web services management, Web services collaboration, Quality of Service for Web services, Web services modeling and performance management, Solution frameworks for building service-oriented applications, Composite Web service creation and enabling infrastructures, Business and scientific applications using Web services and SOA, Business process integration and management using Web services, Standards and specifications of Services Computing, Utility models and solution architectures, Resource acquisition models in Utility Computing, Mathematical foundation of business process modeling, integration and management, Business process modeling, integration, and collaboration.

Additional Information:

TSC is a scholarly, archival journal published quarterly. 

It is noted that only service-oriented grid computing topics will be covered by TSC. 

Please be sure to visit the TSC Taxonomy List. [Link to http://www.computer.org/portal/web/tsc/taxonomy]

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Ling Liu
Georgia Institute of Technology
lingliu@cc.gatech.edu