Defending web services against denial of service attacks using client puzzles

The interoperable and loosely-coupled web services architecture, while beneficial, can be resource-intensive, and is thus susceptible to denial of service (DoS) attacks in which an attacker can use a relatively insignificant amount of resources to exhaust the computational resources of a web service. We investigate the effectiveness of defending web services from DoS attacks using client puzzles, a cryptographic countermeasure which provides a form of gradual authentication by requiring the client to solve some computationally difficult problems before access is granted. In particular, we describe a mechanism for integrating a hash-based puzzle into existing web services frameworks and analyze the effectiveness of the countermeasure using a variety of scenarios on a network testbed. Client puzzles are an effective defence against flooding attacks. They can also mitigate certain types of semantic-based attacks, although they may not be the optimal solution.

Composing services for third-party service delivery

This paper proposes a model-based technique for lowering the entrance barrier for service providers to register services with a marketplace broker, such that the service is rapidly configured to utilize the brokerpsilas local service delivery management components. Specifically, it uses process modeling for supporting the execution steps of a service and shows how service delivery functions (e.g. payment points) ldquolocalrdquo to a service broker can be correctly configured into the process model. By formalizing the different operations in a service delivery function (like payment or settlement) and their allowable execution sequences (full payments must follow partial payments), including cross-function dependencies, it shows how through tool support, the non-technical user can quickly configure service delivery functions in a consistent and complete way.

Efficient Multi-Granularity Service Composition

Dynamic composition of services provides the ability to build complex distributed applications at run time by combining existing services, thus coping with a large variety of complex requirements that cannot be met by individual services alone. However, with the increasing amount of available services that differ in granularity (amount of functionality provided) and qualities, selecting the best combination of services becomes very complex. In response, this paper addresses the challenges of service selection, and makes a twofold contribution. First, a rich representation of compositional planning knowledge is provided, allowing the expression of multiple decompositions of tasks at arbitrary levels of granularity. Second, two distinct search space reduction techniques are introduced, the application of which, prior to performing service selection, results in significant improvement in selection performance in terms of execution time, which is demonstrated via experimental results.

Publishing dynamic state changes of resources through state aware WSDL

A common architecture in today's development of distributed systems is the service-oriented architecture (SOA) implemented using Web services. Until recently, it was difficult to build a SOA based grid/distributed system using Web services due to the inability to learn the state of services. The state of a Web service could only be accessed through specialized clients and/or services. Should the specialized client or service fail, the state can't be accessed. This paper shows the innovative resources via Web instances (RVWI) framework. RVWI grants to web services the ability to show the state of dynamic resources in their WSDL. This was achieved via software components called connectors which watch for any changes in a resource and updates the web service. The significance of this report is the support for resources which can change state between requests and the innovation is the improvement of state updates between the service and discovery services.

Toward exposing and accessing HPC applications in a SaaS cloud

The cost and time of deploying HPC applications on clouds is a problem. Instead of conducting their research discipline specialists are forced to carry out activities for application deployment, publication and ease of access. In response, a new approach for HPC application deployment and access in clouds is proposed. The major innovations are a new approach to deploying and executing HPC applications on IaaS and PaaS clouds, and exposing HPC applications as services. Through three case studies this paper demonstrates the feasibility and effectiveness of the proposed approach that could lead to the building of a SaaS library of discipline-oriented services evocable through user friendly, discipline specific interfaces. The new approach will reduce the time and money needed to deploy and expose discipline HPC applications.

Determinants and economic consequences of voluntary disclosure of internal control weaknesses in China

This paper investigates the determinants and economic consequences of disclosure of internal control weaknesses (ICWs) by Chinese listed firms under the voluntary disclosure regime over 2010-2011. We find that the probability of firms disclosing ICWs is not only associated with firm characteristics such as profitability, age and business complexity, but is also strongly related to the unique attributes of corporate governance and ownership structure in Chinese listed firms, e.g. the independence of the supervisory board, political connections, concentration of the top 3 shareholders' ownership and tradability of shares.Our results show that the severity of the ICWs disclosed is negatively and significantly associated with earnings response coefficients (ERCs), and audit assurance of ICRs has a significant moderating effect on the relationship between ICWs and ERCs. Our research adds further evidence to support the implementation of SOX-type regulations globally.

Self-adaptive volunteered services composition through stimulus-and time-awareness

Volunteered Service Composition (VSC) refers to the process of composing volunteered services and resources. These services are typically published to a pool of voluntary resources. Selection and composition decisions tend to encounter numerous uncertainties: service consumers and applications have little control of these services and tend to be uncertain about their level of support for the desired functionalities and non-functionalities. In this paper, we contribute to a self-awareness framework that implements two levels of awareness, Stimulus-awareness and Time-awareness. The former responds to basic changes in the environment while the latter takes into consideration the historical performance of the services. We have used volunteer service computing as an example to demonstrate the benefits that self-awareness can introduce to self-adaptation. We have compared the Stimulus-and Time-awareness approaches with a recent Ranking approach from the literature. The results show that the Time-awareness level has the advantage of satisfying higher number of requests with lower time cost.

Internal control weakness and accounting conservatism in China

Purpose: The purpose of this study is to investigate the impact of internal control weaknesses on accounting conservatism in Chinese listed firms. It also investigates the relationship between the demand for external audit and accounting conservatism, and whether additional assurance of internal control reports (ICRs) can mitigate the negative impact of ICWs on accounting conservatism.

Design/methodology/approach: An empirical research approach is taken through the use of ordinary least squares (OLS) models and hand-collected internal control weakness data from ICRs released by Chinese listed firms.

Findings: The results of this paper show that the existence of ICWs has a negative effect on accounting conservatism in China. Further, the results demonstrate that both accounting-related and non-accounting-related ICWs affect accounting conservatism. The authors also find that there is a complementary relationship between accounting conservatism and the demand for additional assurance of ICRs, and additional assurance of ICRs can mitigate the negative impact of ICWs on accounting conservatism.

Practical Implications: This study provides timely evidence to Chinese regulators of the possible economic consequences of the official implementation of internal control standard in China from 2012. The findings of this paper can also benefit regulators around the world and, in particular, the regulators in emerging markets that are considering implement regulations similar to the US SOX.

Originality/value: The paper demonstrates that a wider scope of ICWs, including non-accounting-related ICWs, also has a significant impact on accounting conservatism. Therefore, this research provides a more general evidence on the relationship between internal control quality and accounting conservatism.

Exploring the effectiveness of true abnormal data elimination in context-aware web services recommendation

Recent years have witnessed a growing interest in context-aware recommender system (CARS), which explores the impact of context factors on personalized Web services recommendation. Basically, the general idea of CARS methods is to mine historical service invocation records through the process of context-aware similarity computation. It is observed that traditional similarity mining process would very likely generate relatively big deviations of QoS values, due to the dynamic change of contexts. As a consequence, including a considerable amount of deviated QoS values in the similarity calculation would probably result in a poor accuracy for predicting unknown QoS values. In allusion to this problem, this paper first distinguishes two definitions of Abnormal Data and True Abnormal Data, the latter of which should be eliminated. Second, we propose a novel CASR-TADE method by incorporating the effectiveness of True Abnormal Data Elimination into context-aware Web services recommendation. Finally, the experimental evaluations on a real-world Web services dataset show that the proposed CASR-TADE method significantly outperforms other existing approaches.