QCWS: an implementation of QoS-capable multimedia web services
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: The Design of QoS Broker Algorithms for QoS-Capable Web Services
abstract: QoS (quality of service) support in Web services is an important issue since it ensures service usability and utility for each client and, in addition, improves server utilization. In this article, we present a QoS-capable Web service architecture, QCWS, by introducing a QoS broker module between service clients and providers (servers). 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 study two resource allocation algorithms (HQ and RQ) used by QoS brokers acting as the front-end of servers. The goals of the algorithms are to maximize the server resource usage while minimizing the QoS instability for each client. The first algorithm, HQ, assigns a homogeneous service level to all clients on the system and adjusts the service level according to the number of active clients. The second algorithm, RQ, assigns different service levels to clients according to their needs. Both algorithms try to minimize the resource reallocations for existing clients. The QoS performance and instability trade-offs are studied by simulation.

title: A broker-based framework for QoS-aware Web service composition
abstract: Web services are modular web applications that can be independently deployed and invoked by other software or services on the web. This offers enterprises the capability to integrate in-house business services with external Web services to conduct complex business transactions. The integration efficiency and flexibility are critical for services composition. For Web services providing a similar functionality, Quality of Service (QoS) is the main factor to differentiate them. The overall QoS of a business process must meet a user's requirement. In this paper, we propose a broker-based framework to facilitate dynamic integration and adaptation of QoS-aware Web services with end-to-end QoS constraints. The key functions of a dynamic broker include service collection, selection, composition and adaptation. Our study considers both functional and QoS characteristics of Web services to identify the optimal business process solutions.

title: Model Driven Development of Business Process Monitoring and Control Systems
abstract: This paper describes a model-driven approach in monitoring and controlling the behaviour of business processes. The business-level monitoring and control requirements are first described by a series of policies that can be combined together to construct a Directed Acyclic Graph (DAG), which can be regarded as the Platform Independent Model (PIM) for the high level business solution. PIM provides a convenient and clear way for business users to understand, monitor and control the interactions in the target business process. Then the PIM is transformed to an executable representation (Platform Specific Model, PSM), such as BPEL (Business Process Execution Language for Web Service) by decomposing the DAG into several sub-processes and modelling each sub-process as a BPEL process that will be deployed to runtime.

title: A reputation and trust management broker framework for Web applications
abstract: This paper presents a distributed reputation and trust management framework that addresses the challenges of eliciting, evaluating and propagating reputation for Web applications. We propose a broker framework where every service user is associated with a broker who may represent multiple users. A broker collects for its users the distributed reputation ratings about any Web service. In return, a user provides its broker the transaction rating after every transaction with any service in order to build up the reputation database on all services. In addition, brokers form a trust network where they exchange and collect reputation data about services. By delegating trust management to brokers, individual users only need to ask their brokers about the reputation of a service before any transaction with a server. The only overhead for a user is the responsibility to share the reputation feedback with its broker. We present the distributed reputation and trust management framework and show the performance of the system by simulations.

title: Decentralized multiple target tracking using netted collaborative autonomous trackers
abstract: This paper presents a decentralized approach to multiple target tracking. The novelty of this approach lies in the use of a set of autonomous while collaborative trackers to overcome the tracker coalescence problem with linear complexity. In this approach, the individual trackers are autonomous in the sense that they can select targets to track and evaluate themselves, and they are also collaborative since they need to compete for the targets against those trackers that are close to them through communication. The theoretical foundation of this new approach is based on the variational analysis of a Markov network that reveals the collaborative mechanism through fixed point iteration among these trackers and the existence of the equilibriums. In addition, a trained object detector is incorporated to help sense the potential newly appearing targets in the dynamic scene. Experimental results on challenging video sequences demonstrate the effectiveness and efficiency of the proposed method.

title: A Classification Scheme for Trust Functions in Reputation-Based Trust Management
abstract: Reputation is an important means to establish trust in decentralized environments such as the Semantic Web. In reputation-based trust management, an entity's reputation is usually built on feedback from those who have direct interactions with the entity. A trust function is used to infer one's trustworthiness based on such feedback. Many trust functions have been proposed in the literature. They are typically designed for specific application domains, thus differ in a variety of aspects, including trust inference methodologies, complexity and accuracy. In this paper, we propose a classification scheme for trust functions, which will help the systematic analysis and selection of trust functions for particular applications.

title: Switching observation models for contour tracking in clutter
abstract: We propose a generative model approach to contour tracking against nonstationary clutter and to coping with occlusions by explicit modelling and inferring. The proposed dynamic Bayesian networks consist of multiple hidden processes, which model the target, the clutter and the occlusions. The image observation models, which depict the generation of the image features, are conditioned on all the hidden processes. Based on this framework, the tracker can automatically switch among different observation models according to the hidden states of the clutter and occlusions. In addition, the inference of these hidden states provides self-evaluations for the tracker. The tracking and inference are implemented based on sequence Monte Carlo techniques. The effectiveness of the proposed approach to robust tracking and inferring nonstationary clutter and occlusion is demonstrated for a variety of image sequences.

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.

title: Preventing attribute information leakage in automated trust negotiation
abstract: Automated trust negotiation is an approach which establishes trust between strangers through the bilateral, iterative disclosure of digital credentials. Sensitive credentials are protected by access control policies which may also be communicated to the other party. Ideally, sensitive information should not be known by others unless its access control policy has been satisfied. However, due to bilateral information exchange, information may flow to others in a variety of forms, many of which cannot be protected by access control policies alone. In particular, sensitive information may be inferred by observing negotiation participants' behavior even when access control policies are strictly enforced.In this paper, we propose a general framework for the safety of trust negotiation systems. Compared to the existing safety model, our framework focuses on the actual information gain during trust negotiation instead of the exchanged messages. Thus, it directly reflects the essence of safety in sensitive information protection. Based on the proposed framework, we develop policy databases as a mechanism to help prevent unauthorized information inferences during trust negotiation. We show that policy databases achieve the same protection of sensitive information as existing solutions without imposing additional complications to the interaction between negotiation participants or restricting users' autonomy in defining their own policies.