Efficient video similarity measurement and search
We consider the use of meta-data and/or video-domain methods to detect similar videos on the Web. Meta-data is extracted from the textual and hyperlink information associated with each video clip. In the video domain, we apply an efficient similarity detection algorithm called video signature. The idea is to form a signature for each clip by selecting a small number of its frames that are most similar to a set of random seed images. We then apply a statistical pruning algorithm to allow fast detection on very large databases. Using a small ground-truth set, we achieve 90% recall and 95% precision using only 8% of the total number of operations required without pruning. For a database of around 46,000 video clips crawled from the Web, the video signature technique significantly outperforms meta-data in precision and recall. We show that even better performance can be achieved by combining them together. Based on our measurements, each video clip in our database has, on average, 1.53 similar copies.

title: Fast similarity search and clustering of video sequences on the world-wide-web
abstract: We define similar video content as video sequences with almost identical content but possibly compressed at different qualities, reformatted to different sizes and frame-rates, undergone minor editing in either spatial or temporal domain, or summarized into keyframe sequences. Building a search engine to identify such similar content in the World-Wide Web requires: 1) robust video similarity measurements; 2) fast similarity search techniques on large databases; and 3) intuitive organization of search results. In a previous paper, we proposed a randomized technique called the video signature (ViSig) method for video similarity measurement. In this paper, we focus on the remaining two issues by proposing a feature extraction scheme for fast similarity search, and a clustering algorithm for identification of similar clusters. Similar to many other content-based methods, the ViSig method uses high-dimensional feature vectors to represent video. To warrant a fast response time for similarity searches on high dimensional vectors, we propose a novel nonlinear feature extraction scheme on arbitrary metric spaces that combines the triangle inequality with the classical Principal Component Analysis (PCA). We show experimentally that the proposed technique outperforms PCA, Fastmap, Triangle-Inequality Pruning, and Haar wavelet on signature data. To further improve retrieval performance, and provide better organization of similarity search results, we introduce a new graph-theoretical clustering algorithm on large databases of signatures. This algorithm treats all signatures as an abstract threshold graph, where the distance threshold is determined based on local data statistics. Similar clusters are then identified as highly connected regions in the graph. By measuring the retrieval performance against a ground-truth set, we show that our proposed algorithm outperforms simple thresholding, single-link and complete-link hierarchical clustering techniques.

title: An efficient message authentication scheme for link state routing
abstract: We study methods for reducing the cost of secure link state routing. In secure link state routing, routers may need to verify the authenticity of many routing updates, and some routers such as border routers may need to sign many routing updates. Previous work such as public-key based schemes are very expensive computationally or have certain limitations. This paper presents an efficient solution, based on a detection-diagnosis-recovery approach, for the link state routing update authentication problem. Our scheme is scalable to handle large networks, applicable to routing protocols that use multiple-valued cost metrics, and applicable even, when link states change frequently.

title: Decomposing the queue length distribution of processor-sharing models into queue lengths of permanent customer queues
abstract: We obtain a decomposition result for the steady state queue length distribution in egalitarian processor-sharing (PS) models. In particular, for multi-class egalitarian PS queues, we show that the marginal queue length distribution for each class equals the queue length distribution of an equivalent single class PS model with a random number of permanent customers. Similarly, the mean sojourn time (conditioned on the initial service requirement) for each class can be obtained by conditioning on the number of permanent customers. The decomposition result implies linear relations between the marginal queue length probabilities, which also hold for other PS models such as the egalitarian PS models with state-dependent system capacity that only depends on the total number of customers in the system. Based on the exact decomposition result for egalitarian PS queues, we propose a similar decomposition for discriminatory processor-sharing (DPS) models, and numerically show that the approximation is accurate for moderate differences in service weights.

title: Automatic generation of database instances for white-box testing
abstract: Testing is a critical activity for database application programs as faults if undetected could lead to unrecoverable data loss. Database application programs typically contain statements written in an imperative programming language with embedded data manipulation commands, such as SQL. However relatively little study has been made in the testing of database application programs. In particular, few testing techniques explicitly consider the inclusion of database instances in the selection of test cases and the generation of test data input. In this paper, we study the generation of database instances that respect the semantics of SQL statements embedded in a database application program. The paper also describes a supporting tool which generates a set of constraints. These constraints collectively represent a property against which the program is tested. Database instances for program testing can be derived by solving the set of constraints using existing constraint solvers.

title: Integrating Legacy Sites into Web Services with WebXcript
abstract: Despite the recent uprising of the Web Services technology for programmatic interfaces of business-to-business (B2B) E-commerce services (e-services) over the Internet, most existing sites can only support human interactions with Hypertext Markup Language (HTML) through web browsers. Automating third-party client access into Web Services generally requires developing sophisticated programs to simulate human access by handling HTML pages. However, these HTML interfaces vary across web sites, and are often subject to changes. Client maintenance is therefore tedious and expensive. Even for the site owner, it may still require much effort in redeveloping the underlying presentation and application logics. This motivates our study for the requirement and the formulation of a conceptual model for such automation. Based on the requirement, we develop a novel approach to automating dialogs with web-based services (particularly for cross-organizational processes), using a high-level script language, called WebXcript language. The language provides features for HTML forms-based dialogues and eXtended Markup Language (XML) messaging. The XML syntax of WebXcript further enables convenient user authoring and easy engine development with extensively available XML tools. It supports expected responses and exception handling. We further propose a wrapper architecture based on WebXcript to integrate legacy sites into Web Services, where Web Service Definition Language (WSDL) interfaces are generated from high-level mappings from database or WebXcript parameter definitions. We demonstrate the applicability of our approach with examples in integrating distributed information, online ordering, and XML messaging, together with discussions on our experiences and the advantages of our approach.

title: Rights protection for digital contents redistribution over the Internet
abstract: Although the customer-to-customer (C2C) business model has been around for years, second-hand markets of digital contents over the Internet are still unpopular. A key factor to the success of second-hand markets lies in the support of rights management of digital contents redistribution over the Internet. Although various watermarking protocols have been proposed to achieve digital rights protection over the Internet, they do not generally provide protection over a second-hand market. We propose a buyer-reseller watermarking protocol that protects the interests of buyers, resellers and the original sellers. The protocol is adapted from a previous work proposed by Memon and Wong (2001), which defends the interests of buyers against sellers' unethical distribution of watermarked contents. Our protocol makes use of watermark certificates to distribute the information of buyers' identities. An implementation outline of the proposed protocol is given.