Towards automating overlay network management

Overlay networks are becoming widely used for content delivery because they provide effective and reliable services that are not otherwise available. However, they can negatively affect each other as well as the underlying network. A management system that controls and adapts their behavior is therefore needed. This will meet not only the specific demands of the users but also those of the network and service providers. This paper presents a novel approach to the issue of automating overlay network management. In contrast to existing management approaches which require static a priori policy configurations, policies are created dynamically. A policy layer consists of a set of policy enforcement points and policy decision points. This is used to capture the goals of users, services, and networks into network-level objectives. The behavior of the overlay network is adapted to the changing conditions in its environment. The creation, adaptation, and termination of overlays are achieved through policies. Policies are generated and enforced on the fly from the context information of the user, the network and the service provider. The new approach provides users and applications with more flexibility to dynamically change their quality-of-service requirements while maintaining smooth quality-of-service delivery. We show the advantages of our architecture and provide simulation results to verify its effectiveness.     

Approaching Secure Communications in a Message-Oriented Mobile Computing Environment

The Personal Mobility Management System (PMMS), an agent-based message-oriented mobile computing application developed at Multimedia and Mobile Agent Research Laboratory, aims to provide personalized services and resources access to its nomadic users within a virtual network across different organizations. This paper analyses and discusses the security weaknesses exposed in the system architecture, then proposes several security frameworks to overcoming these security concerns. The paper tries to address and provide a general architectural solution to ensure secure communications for a typical message-oriented mobile computing system.     

A multimedia medical communications system

The problem of communicating the radiologist's findings to the attending physician is introduced, and it is shown why it is essentially a multimedia communication problem. A multimedia communications system that was designed with a focus on database and medical reports organization and architecture is described. A report is presented of some of the key results of an in-house trial linking the Department of Radiological Sciences and the Emergency Department at the Ottawa Civic Hospital, Canada, a 950-bed tertiary-care teaching hospital     

Investigation of electrical and optical measurements of silicon nanocrystals embedded in SiO2 matrix

Samples containing silicon nanocrystals (Si-nc) with radius of approximately 3 nm embedded in SiO₂ exhibit a strong PL emission around 750 nm because of the quantum confinement of the exciton inside the Si-nc. To characterize the contribution of absorption by Si-nc to the photo-electric efficiency of silicon, metal–oxide–semiconductor structures were fabricated, without and with Si-nc embedded in silicon oxide and electrically characterized in the dark and under illumination. Samples containing Si-nc show a relatively large photocurrent compared to samples without Si-nc. Electron trapping and de-trapping in Si-nc was also observed by capacitance–frequency measurements showing a decrease of photo-generated electrons under illumination at high frequency. The efficiency of the photo-generated electrons from Si-nc was evaluated and shows a high EQE below 650 nm suggesting that Si-nc could be an interesting candidate for an the third generation photovoltaic solar cells.     

Network anomaly diagnosis via statistical analysis and evidential reasoning

This paper investigates the efficiency of diagnosing network anomalies using concepts of statistical analysis and evidential reasoning. A bi-cycle of auto-regression is first applied to model increments in the values of network monitoring variables to accurately detect network anomalies. To classify the rootcause of the detected anomalies, concepts of evidential reasoning of Dempster-Shafer theory are employed; the root-cause of a network failure is inferred by gathering pieces of evidence concerning different groups of candidate failures obtained from a training set of detected anomalies and their corresponding root-causes. These groups are then refined to infer the exact cause of failure when evidence accumulates using the Dempster rule of combinations. To handle cases of imbalanced training sets, two new approaches for assigning belief values to different anomaly classes are also proposed. Performance analysis and results demonstrate the accuracy of the proposed scheme in detecting anomalies using real data.     

Multimedia teleorchestra with independent sources: Part 2 — synchronization algorithms

Based on the time-flow graph models proposed for the multimedia presentation scenarios, a scheduling algorithm and control scheme are presented for the synchronization control which involves multiple sources in a teleorchestra system. In the scheduling, a synchronization dialogue among the independent sources will be conducted to evaluate the presentation scenario. Then the real-time data objects from the different sources can be synchronized in the remote presentation according to the required scenario. The algorithm can be performed in a distributed manner.     

Policy-driven personalized multimedia services for mobile users

This paper proposes an agent-based service provisioning system for mobile users. It describes a set of cooperative agents distributed over different sites that work together to provide personalized services for mobile users over the Internet. Users moving outside the office are able to maintain an off ice-like environment at home, or at temporary locations such as a meeting at another company, a business trip, or a hotel. Agents representing the end-users and the system agents engage in a negotiation process to facilitate access to personalized services at other sites. This access is obtained in accordance with the users' home policies as well as those at their current location. An Adaptive Service Presentation agent is used to adapt the service presentation to the capabilities of the users' workstations, laptops, phones, PDAs, or other devices. This work is conducted in Canada as part of the Mobile Agent Alliance project involving the University of Ottawa, the National Research Council, and the Mitel Corporation.     

Feature set and architecture of a multimedia news system over an ATM network

In this paper we discuss a multimedia news system that we have developed in the Multimedia Information Research Laboratory at the University of Ottawa and beyond. We focus on the feature set—that is, the tools and facilities associated with the system. We explain the functionality of each and give some real examples of the system in action. We then outline the architecture—the system consists of a production server for document authoring, a conferencing system for collaborative news article creation, a content database for authors, a hypernews database for hypermedia news documents, a news database server with aging and archiving, and user sites. The goal was to have all components of the system communicating on OCRInet—an R&D ATM network in the Ottawa region. We then introduce the challenges of representing and browsing large video objects and to this end we introduce a novel solution that we call video-tiles. This video tool is an effective way to browse large news videos that are frequently connected with our multimedia news articles.