Service selection algorithms for Web services with end-to-end QoS constraints
Web services are new forms of Internet software that can be universally deployed and invoked using standard protocols. Services from different providers can be integrated into a composite service regardless of their locations, platforms, and/or execution speeds to implement complex business processes and transactions. In this paper, we study the end-to-end QoS issues of composite services by utilizing a QoS broker that is responsible for selecting and coordinating the individual service component. We design the service selection algorithms used by QoS brokers to construct the optimal composite service. The objective of the algorithms is to maximize the user-defined utility function value while meeting the end-to-end delay constraint. We propose two solution approaches to the service selection problem: the combinatorial approach, by modeling the problem as the Multiple Choice Knapsack Problem (MCKP), and the graph approach, by modeling the problem as the constrained shortest path problem in the graph theory. We study efficient solutions for each approach.

title: Modeling and Measuring Privacy Risks in QoS Web Services
abstract: The privacy issue for QoS Web services is considered. As more Web services are constructed and deployed, many of our personal needs may be served by more than one service providers regardless of their platforms and implementation technologies. Service selection is performed by comparing the QoS attributes of all candidate services. Releasing private data without due control may raise the risk of allowing potential adversaries to collect, reveal or utilize one's data in undesirable ways. We propose a QoS model that quantifies a user's privacy risk in order to make the service selection process manageable. The privacy risk is derived using the percentage of the private data set to be released, and user-defined context-oriented weights that quantify the potential damage of privacy leaking in a specific context. We have included privacy risk cost as one of the QoS parameters by extending the end-to-end QoS composition algorithms developed previously

title: QCWS: an implementation of QoS-capable multimedia web services
abstract: QoS (Quality of Service), which defines service quality such as latency, availability, timeliness and reliability, is important for web applications that provide real-time information, multimedia content, or time-critical services. Many web applications are best implemented by servers with a guaranteed server processing capacity. In this research, we study the QoS control issues using the current Web services standards. We propose a QoS-capable Web service architecture, QCWS, by deploying a QoS broker between Web service clients and providers. The functions of the QoS broker module include tracking QoS information about servers, making selection decisions for clients, and negotiating with servers to get QoS agreements. We have implemented a QCWS prototype using IBM WSDK, enhanced with simple QoS capabilities. We have measured the performance running under different service priorities.

title: Service Selection Algorithms for Web Services with End-to-End QoS Constraints
abstract: Web services are new forms of Internet software that can be universally deployed and invoked using standard protocol. Services from different providers can be integrated to provide composite services. In this paper, we study the end-to-end QoS issues of composite service by utilizing a QoS broker that is responsible for coordinating the individual service component to meet the quality constraint. We design the service selection algorithms used by QoS brokers to meet end-to-end QoS constraints. The objective of the algorithms is to maximize the user-defined utility while meeting the end-to-end delay constraint. We model the problem as the multiple choice knapsack problem (MCKP) and provide efficient solutions. The algorithms are tested for their performance.

title: Service Selection Algorithms for Composing Complex Services with Multiple QoS Constraints
abstract: One of the promises of the service-oriented architecture (SOA) is that complex services can be composed using individual services. Individual services can be selected and integrated either statically or dynamically based on the service functionalities and performance constraints. For many distributed applications, the runtime performance (e.g. end-to-end delay, cost, reliability and availability) of complex services are very important. In our earlier work, we have studied the service selection problem for complex services with only one QoS constraint. This paper extends the service selection problem to multiple QoS constraints. The problem can be modelled in two ways: the combinatorial model and the graph model. The combinatorial model defines the problem as the multi-dimension multi-choice 0-1 knapsack problem (MMKP). The graph model defines the problem as the multi-constraint optimal path (MCOP) problem. We propose algorithms for both models and study their performances by test cases. We also compare the pros & cons between the two models.

title: Limiting the Disclosure of Access Control Policies during Automated Trust Negotiation
abstract: Automated trust negotiation is a new approach to establishing trust between strangers through the exchange of property-based digital credentials, and the use of mobile access control policies that specify what combinations of credentials a stranger must supply in order to gain access to each local service or credential. In this paper, we show that access control policies can also contain sensitive information that should be protected from inappropriate access by strangers during negotiation. We present and analyze two automated trust negotiation strategies that support protection for access control policies. The first is the relevant credentials set strategy, which does not directly disclose access control policies and has a fast running time, but may disclose more credentials than strictly necessary. The second strategy is the all relevant policies strategy, which freely discloses all relevant access control policies that the other negotiating party has earned access to during negotiation, and offers the possibility of disclosing fewer credentials

title: Tracking articulated body by dynamic Markov network
abstract: A new method for visual tracking of articulated objects is presented. Analyzing articulated motion is challenging because the dimensionality increase potentially demands tremendous increase of computation. To ease this problem, we propose an approach that analyzes subparts locally while reinforcing the structural constraints at the mean time. The computational model of the proposed approach is based on a dynamic Markov network, a generative model which characterizes the dynamics and the image observations of each individual subpart as well as the motion constraints among different subparts. Probabilistic variational analysis of the model reveals a mean field approximation to the posterior densities of each subparts given visual evidence, and provides a computationally efficient way for such a difficult Bayesian inference problem. In addition, we design mean field Monte Carlo (MFMC) algorithms, in which a set of low dimensional particle filters interact with each other and solve the high dimensional problem collaboratively. Extensive experiments on tracking human body parts demonstrate the effectiveness, significance and computational efficiency of the proposed method.

title: Policy migration for sensitive credentials in trust negotiation
abstract: Trust negotiation is an approach to establishing trust between strangers through the bilateral, iterative disclosure of digital credentials. Under automated trust negotiation, access control policies are associated with sensitive credentials to control under what circumstances those credentials can be disclosed. Ideally, the information in a user's sensitive credential should not be known by others unless the corresponding policy is satisfied. However, the original model for user interaction in trust negotiation has pitfalls which can be easily exploited to infer one's private information, even if access control policies are strictly enforced. To preserve one's privacy, a more flexible interaction model for trust negotiation is required. On the other hand, it is also desirable for two parties to be able to establish trust whenever possible. There is potentially a conflict between privacy preservation and the assurance of a successful trust negotiation. In this paper, we identify the situation where sensitive information can be inferred through observing one's behavior in trust negotiation. Then we propose policy migration as one approach to preventing such inference. Compared to previously proposed approaches, policy migration has a low management overhead, and provides a nice balance between inference prevention and guarantees of success in trust establishment. We also discuss the limitations of policy migration, and possible directions for more comprehensive solutions.

title: Identifying Error-Prone Software&#8212;An Empirical Study
abstract: A major portion of the effort expended in developing commercial software today is associated with program testing. Schedule and/ or resource constraints frequently require that testing be conducted so as to uncover the greatest number of errors possible in the time allowed. In this paper we describe a study undertaken to assess the potential usefulness of various product-and process-related measures in identifying error-prone software. Our goal was to establish an empirical basis for the efficient utilization of limited testing resources using objective, measurable criteria. Through a detailed analysis of three software products and their error discovery histories, we have found simple metrics related to the amount of data and the structural complexity of programs to be of value for this purpose.

title: An identifiability-based access control model for privacy protection in open systems
abstract: We argue that in open systems one's private information disclosure needs to be dynamically controlled based on both its sensitivity and the possibility that a user's identity is revealed. Then we propose an identifiability-based access control scheme, which not only properly control usrers' private information, but also increase users' access to web services.