A queueing network model for a distributed database testbed system

A queuing network model for analyzing the performance of a distributed database testbed system with a transaction workload is developed. The model includes the effects of the concurrency control protocol (two-phase locking with distributed deadlock detection), the transaction recovery protocol (write-ahead logging of before-images), and the commit protocol (centralized two-phase commit) used in the testbed system. The queuing model differs from previous analytical models in three major aspects. First, it is a model for a distributed transaction processing system. Second, it is more general and integrated than previous analytical models. Finally, it reflects a functioning distributed database testbed system and is validated against performance measurements     

An open framework for a multimedia medical document system (a multimedia document system framework)

A novel and generalized open framework for multimedia information manipulation is proposed. The document system consists of functional modules for capturing, storing and presenting multimedia data. These modules work independently and communicate through aHyperDocument Interfacelayer. The modular approach has the added advantage of easy-to-maintain and the convenience for future enhancements. Hypermedia and temporal –spatial relationships between document media nodes are embedded into the data structure to support flexible presentation of multimedia information. Windows and a specially designedDocument Tree Dialogprovide an environment for efficient and user-friendly information retrieval. Other system issues such as security and customization are also addressed in the design. Based on this approach, a medical multimedia document system to handle cardiac catheterization record (CCR) was designed as a demonstration for the research idea. The proposed design can be applied and extended to cover a variety of multimedia applications.     

MING-I: a distributed interactive multimedia document development mechanism

The next generation of interactive multimedia documents can contain both static media, e.g., text, graph, image, and continuous media, e.g., audio and video, and can provide user interactions in distributed environments. However, the temporal information of multimedia documents cannot be described using traditional document structures, e.g., Open Document Architecture (ODA) and Standard Generalized Mark-up Language (SGML); the continuous transmission of media units also raises some new synchronization problems, which have not been met before, for processing user interactions. Thus, developing a distributed interactive multimedia document system should resolve the issues of document model, presentation control architecture, and control scheme. In this paper, we (i) propose a new multimedia document model that contains the logical structure, the layout structure, and the temporal structure to formally describe multimedia documents, and (ii) point out main interaction-based synchronization problems, and propose a control architecture and a token-based control scheme to solve these interaction-based synchronization problems. Based on the proposed document model, control architecture, and control scheme, a distributed interactive multimedia document development mechanism, which is called MING-I, is developed on SUN workstations.     

PressBase : a presentation synchronization database for distributed multimedia systems

Multimedia presentations are the basic objects of multimedia databases. Since a multimedia presentation is not an instant display of a query result, the control knowledge (or synchronization requirements) has to be incorporated into the database and necessary precautions have to be taken for a lengthy presentation. Active databases provide a mechanism for incorporation of control knowledge by using event-condition-action (ECA) rules. In this paper, we describe how multimedia synchronization can be handled within a database using ECA rules. We present a prototype presentation synchronization database, named as PressBase, for distributed multimedia systems. We have adopted one of the synchronization models, SynchRuler, and then incorporated into a relational database system.     

A spatio-temporal semantic model for multimedia database systemsand multimedia information systems

As more information sources become available in multimedia systems, the development of abstract semantic models for video, audio, text, and image data is becoming very important. An abstract semantic model has two requirements: it should be rich enough to provide a friendly interface of multimedia presentation synchronization schedules to the users and it should be a good programming data structure for implementation in order to control multimedia playback. An abstract semantic model based on an augmented transition network (ATN) is presented. The inputs for ATNs are modeled by multimedia input strings. Multimedia input strings provide an efficient means for iconic indexing of the temporal/spatial relations of media streams and semantic objects. An ATN and its subnetworks are used to represent the appearing sequence of media streams and semantic objects. The arc label is a substring of a multimedia input string. In this design, a presentation is driven by a multimedia input string. Each subnetwork has its own multimedia input string. Database queries relative to text, image, and video can be answered via substring matching at subnetworks. Multimedia browsing allows users the flexibility to select any part of the presentation they prefer to see. This means that the ATN and its subnetworks can be included in multimedia database systems which are controlled by a database management system (DBMS). User interactions and loops are also provided in an ATN. Therefore, ATNs provide three major capabilities: multimedia presentations, temporal/spatial multimedia database searching, and multimedia browsing     

一种分布式多媒体数据仓库模型

多媒体数据采掘是从大型多媒体数据库中提取高层的多媒体信息及知识。介绍一种分布式多媒体数据仓库模型──ＣＭＳ模型的体系结构及存储结构,并构造了具有综合处理各种媒体数据,能够对这些媒体数据进行修改、查询的军用多媒体数据仓库原型系统。     

SuiteSound: a system for distributed collaborative multimedia

SuiteSound, a programming environment with integrated support for multimedia, is discussed. SuiteSound is built in the Suite object-based system on a conventional UNIX operating system. SuiteSound objects incorporate multimedia by creating flows and filters. Flows are streams of multimedia data moving through a sequence of objects. They bridge the gap between objects representing the state of an entity at a discrete point in time and space and continuous media such as live audio or video. Filters are intermediate objects between the source and destination of a flow. They take flow as input, perform one of several operations such as multiplex-in, multiplex-out, gain control, or silence deletion on it, and send the resulting flow to its destination. In effect, they provide a virtual device interface for the application programmer that is uniform and independent of any physical device. The design and implementation of SuiteSound on the Sun SparcStation are described. Experiments performed to determine the network and CPU load of the sound tool are reviewed     

JINSIL: A middleware for presentation of composite multimedia objects in a distributed environment

In a distributed environment, the presentation of structured, composite multimedia information poses new challenges in dealing with variable bandwidth (BW) requirements and synchronization of media data objects. The detailed knowledge of BW requirements obtained by analyzing document structure can be used for efficient utilization of system resources. A client–server environment consists of various system components that are either dedicated to a client (e.g., client buffer space and BW) or shared across multiple clients (e.g., server buffer space and BW). A shared server could benefit from fine granularity advanced reservation of resources based on true BW requirements. Prefetching by utilizing advance knowledge of BW requirements can further improve resource utilization. The prefetch schedule needs also to be aware of the BW fragmentation in a partitioned server. In this paper, we describe the JINSIL middleware for retrieval of a composite document that takes into account the available BW and buffer resources and the nature of sharing in each component on delivery paths. It reshapes BW requirements, creates prefetch schedules for efficient resource utilization in clients and servers, and reserves necessary BW and buffer space. We also consider good choices for placement of prefetch buffers across client and server nodes.     

A distributed full-text top-k document dissemination system in distributed hash tables

Recent years witnessed the explosive growth of ??live?? web content in the World Wide Web like Weblogs, RSS feeds, and real-time news, etc. The popular usage of RSS feeds/readers enables end users to subscribe for favorite contents via input RSS URLs. However, the RSS feeds/readers architecture suffers from (i) the high bandwidth consumption issue, and (ii) limited filtering semantics. In this paper, we proposed a stateful full text dissemination scheme over structured P2Ps to address both issues. Specifically, for the semantic side, end users are allowed to subscribe for favorite contents via input keywords; for the network bandwidth side, the cooperative content polling, filtering and disseminating via DHT-based P2P overlay networks save the network bandwidth consumption. Our contributions include the novel techniques to (i) reduce the unit-publishing cost by pruning irreverent documents during the forwarding path towards destinations, and (ii) reduce the publication amount by selecting a very small number of meaningful terms. Based on real data sets, our experimental results show that the proposed scheme can significantly reduce the publishing cost with low maintenance overhead and a high document quality.     

Using mobile phones for secure, distributed document processing in the developing world

Paper plays an essential role in many information ecologies in the developing world, but it can be inefficient and inflexible. We've developed an information services architecture that uses a smart phone equipped with a built-in digital camera to process augmented paper documents. The CAM document-processing framework exploits smart mobile phones' utility, usability, and growing ubiquity to link paper with modern information tools. CAM, so called because the phone's camera plays a key role in the user interface, is a three-tiered, document-based architecture for providing remote rural information services. The CAM framework comprises four components: CamForms, CamShell, CamBrowser, and CamServer.     

An object-oriented multimedia database system for a news-on-demand application

We describe the design of a multimedia database management system for a distributed news-on-demand multimedia information system. News-on-demand is an application that uses broadband network services to deliver news articles to subscribers in the form of multimedia documents. Different news providers insert articles into the database, which are then accessed by users remotely, over a broadband, asynchronous transfer-mode (ATM) network. The particulars of our design are an object-oriented approach and strict adherence to international standards, in particular the Standard Generalized Mark-up Language (SGML) and Hy-Time. The multimedia database system has a visual query facility, which is also described in this paper. The visual query interface provides three major facilities for end users: presentation, navigation, and querying of multimedia news documents. The main focus, however, is the querying of multimedia objects stored in the database.     

A distributed digital rights management model for secure information-distribution systems

There is a need to protect digital information content and the associated usage rights from unauthorized access, use, and dissemination. The protection mechanisms should meet the requirements for the correct management of fine-grained access and usage controls and the protection of user privacy. Digital rights management (DRM) solutions have significant relevance in this context. This paper describes a distributed DRM model for a secure information-distribution system consisting of six trust-building blocks. These are (i) the user application, (ii) the authentication and authorization module, (iii) Rights-Carrying and Self-Enforcing Objects (SEOs), (iv) the privacy enforcement module, (v) theUsage Tracking and Monitoring Proxy (UTMP), and (vi) thesecurity infrastructure. SEOs are information objects that carry access and usage rights and are responsible for the fine-grained enforcement of these rights. The security infrastructure plays a pivotal role in the creation, distribution, storage, manipulation, and communication of information objects across organizational boundaries with the required level of security. Our model was originally developed for an Internet-based learning project in Norwegian schools and meets most of the aforementioned requirements.     

基于移动Agent的分布式数据库的协同安全模型

随着各种分布式计算的广泛应用,移动Agent技术引起了人们越来越多的关注.在移动Agent的应用环境中,数据传输、服务器资源.移动Agent运行环境和移动Agent自身安全等方面的安全性问题日益突出.同时移动Agent应用系统中各个数据处理Agent之间的自主进行协商和协调也是一个有待解决的问题.针对这些问题,提出了一种基于移动Agent的分布式数据库的协同安全模型,来初步解决移动Agent的分布式数据库安全性和Agent之间协调工作的问题.     

ZYX-a multimedia document model for reuse and adaptationof multimedia content

Advanced multimedia applications require adequate support for the modeling of multimedia content by multimedia document models. More and more this support calls for not only the adequate modeling of the temporal and spatial course of a multimedia presentation and its interactions, but also for the partial reuse of multimedia documents and adaptation to a given user context. However, our thorough investigation of existing standards for multimedia document models such as HTML, MHEG, SMIL, and HyTime leads to us the conclusion that these standard models do not provide sufficient modeling support for reuse and adaptation. Therefore, we propose a new approach for the modeling of adaptable and reusable multimedia content, the Z_YX model. The model offers primitives that provide-beyond the more or less common primitives for temporal, spatial, and interaction modeling-a variform support for reuse of structure and layout of document fragments and for the adaptation of the content and its presentation to the user context. We present the model in detail and illustrate the application and effectiveness of these concepts by samples taken from our Cardio-OP application in the domain of cardiac surgery. With the Z_YX model, we developed a comprehensive means for advanced multimedia content creation: support for template-driven authoring of multimedia content and support for flexible, dynamic composition of multimedia documents customized to the user's local context and needs. The approach significantly impacts and supports the authoring process in terms of methodology and economic aspects     

Quality-based I/O resource managementfor multimedia document database servers

Slow access to disk-based multimedia data is a major limiting factor in the performance of modern multimedia Web servers connected over broadband networks. The I/O bottleneck becomes even more pronounced for currently evolving systems handling multimedia data, such as audio and video. Retrieval of complex multimedia documents needs to be handled at two levels: I/O bandwidth management for multiple multimedia streams, and interstream and intrastream synchronization for multimedia objects constituting these documents. In this paper, based on the diverse characteristics of multimedia data, we propose efficient techniques for synchronous retrieval and delivery of such data from the storage system to the main memory of the server. We propose methods to quantify user perceived quality via quality-of-presentation (QoP) parameters. We combine QoP and Object Composition Petri Net (OCPN) multimedia data modeling to develop techniques for efficient synchronous retrieval of multimedia data. Since I/O bandwidth is a precious resource, the proposed techniques have low overhead, which is , where m is the number of logical I/O channels and n is the total number of frames of multimedia data in a scheduling period. We simulate the relative performance of these techniques under diverse I/O conditions and determine the tradeoffs between the system resources, such as memory, bandwidth, and the improvement in QoP for multimedia applications.Published online: 9 February 2005 Correspondence to: M. Farrukh Khan     

A comparison of a network structure and a database system used for document retrieval

Database systems have many advantages for implementing document retrieval systems. One of the main advantages would be the integration of data and text handling in a single information system. However, it has not been clear how much a database implementation would cost in terms of efficiency. In this paper, we compare a database implementation and a stand-alone implementation of a flexible representation of the content of documents and the associated search strategies. The representation used is a network of document and index term nodes. The comparison shows that certain features of a database system can have a significant effect on the efficiency of the implementation. Despite this, it appears that a database implementation of a sophisticated document retrieval system can be competitive with a stand-alone implementation.     

A transport-level proxy for secure multimedia streams

To provide a secure traversal service, firewalls need more than static packet filtering and application-level proxies. SOCKS (Secure sOCKets) is an application-independent transport-level proxy that offers user-level authentification and data encryption. An extended SOCKS UDP (user datagram protocol) binding model with appropriate socket calls is proposed to provide complete support for UDP-based multimedia streaming applications     

A document comparison scheme for secure duplicate detection

The ever-growing volumes of textual information from various sources have fostered the development of digital libraries, making digital content readily accessible but also easy for malicious users to plagiarize, thus giving rise to security problems. In this paper, we introduce a duplicate detection scheme that is able to determine, with a particularly high accuracy, the degree to which one document is similar to another. Our pairwise document comparison scheme detects the resemblance between the content of documents by considering document chunks, representing contexts of words selected from the text. The resulting duplicate detection technique presents a good level of security in the protection of intellectual property while improving the availability of the data stored in the digital library and the correctness of the search results. Finally, the paper addresses efficiency and scalability issues by introducing new data reduction techniques.     

Performance evaluation of snapshot isolation in distributed database system under failure-prone environment

Database systems are widely used in many fields. As the scale of database systems increases, more firms decide to deploy the database system in a distributed environment for the sake of data integrity fault tolerance. For guaranteeing the consistency of data, database management systems adopt isolation policies. This paper discusses probabilistic models for snapshot isolation of database management system. Snapshot isolation is an effective method to enhance the consistency of database system, although it degrades the system performance where the system has large network latency such as distributed database system. Also, under the failure-prone environment, a restart scheme is considered as one countermeasure. This paper proposes probabilistic models for the dynamics of snapshot isolation of database system and exhibits the optimization of system performance with respect to updating interval of snapshot isolation within the failure-prone environment from the analytical point of view. Numerical experiments are conducted to validate the effectiveness of analytical results by using real traffic data.