Building a large and efficient hybrid peer-to-peer Internet caching system

Proxy hit ratios tend to decrease as the demand and supply of Web contents are becoming more diverse. By case studies, we quantitatively confirm this trend and observe significant document duplications among a proxy and its client browsers' caches. One reason behind this trend is that the client/server Web caching model does not support direct resource sharing among clients, causing the Web contents and the network bandwidths among clients to be relatively underutilized. To address these limits and improve Web caching performance, we have extensively enhanced and deployed our browsers-aware framework, a peer-to-peer Web caching management scheme. We make the browsers and their proxy share the contents to exploit the neglected but rich data locality in browsers and reduce document duplications among the proxy and browsers' caches to effectively utilize the Web contents and network bandwidth among clients. The objective of our scheme is to improve the scalability of proxy-based caching both in the number of connected clients and in the diversity of Web documents. We show that building such a caching system with considerations of sharing contents among clients, minimizing document duplications, and achieving data integrity and communication anonymity is not only feasible but also highly effective.     

XML-based specification for Web services document security

The Internet and related technologies have seen tremendous growth in distributed applications such as medicine, education, e-commerce, and digital libraries. As demand increases for online content and integrated, automated services, various applications employ Web services technology for document exchange among data repositories. Web services provide a mechanism to expose data and functionality using standard protocols, and hence to integrate many features that enhance Web applications. XML, a well-established text format, is playing an increasingly important role in supporting Web services. XML separates data from style and format definition and allows uniform representation, interchange, sharing, and dissemination of information content over the Internet. XML and Web services provide a simplified application integration framework that drives demand for models that support secure information interchange. Providing document security in XML-based Web services requires access control models that offer specific capabilities. Our XML-based access control specification language addresses a new set of challenges that traditional security models do not address.     

Feature pattern based representation of multimedia documents for efficient knowledge discovery

The rapid growth of multimedia documents has raised huge demand for sophisticated multimedia knowledge discovery systems. The knowledge extraction of the documents mainly relies on the data representation model and the document representation model. As the multimedia document comprised of multimodal multimedia objects, the data representation depends on modality of the objects. The multimodal objects require distinct processing and feature extraction methods resulting in different features with different dimensionalities. Managing multiple types of features is challenging for knowledge extraction tasks. The unified representation of multimedia document benefits the knowledge extraction process, as they are represented by same type of features. The appropriate document representation will benefit the overall decision making process by reducing the search time and memory requirements. In this paper, we propose a domain converting method known as Multimedia to Signal converter (MSC) to represent the multimodal multimedia document in an unified representation by converting multimodal objects as signal objects. A tree based approach known as Multimedia Feature Pattern (MFP) tree is proposed for the compact representation of multimedia documents in terms of features of multimedia objects. The effectiveness of the proposed framework is evaluated by performing the experiments on four multimodal datasets. Experimental results show that the unified representation of multimedia documents helped in improving the classification accuracy for the documents. The MFP tree based representation of multimedia documents not only reduces the search time and memory requirements, also outperforms the competitive approaches for search and retrieval of multimedia documents.     

Retrieval schedules based on resource availability and flexible presentation specifications

A distributed multimedia document presentation involves retrieval of objects from one or more document servers and their presentation at the client system. The presentation of the multimedia objects has to be carried out in accordance with the specification of temporal relationships between the objects. The retrieval of multimedia objects from the document server(s) is influenced by factors such as temporal specification of objects presentations, throughput offered by the network service provider, and the buffer resources on the client system. Flexibility in the temporal specification of the multimedia document may help in deriving an object retrieval schedule that can handle variations in network throughput and buffer resource availability. In this paper, we develop techniques for deriving a flexible object retrieval schedule for a distributed multimedia document presentation. The schedule is based on flexible temporal specification of the multimedia document using the difference constrai nts approach. We show how the derived retrieval schedule can be validated and modified to ensure that it can work with the offered network throughput and the available buffer resources.     

Analysis of task assignment policies in scalable distributedweb-server systems

A distributed multiserver Web site can provide the scalability necessary to keep up with growing client demand at popular sites. Load balancing of these distributed Web-server systems, consisting of multiple, homogeneous Web servers for document retrieval and a Domain Name Server (DNS) for address resolution, opens interesting new problems. In this paper, we investigate the effects of using a more active DNS which, as an atypical centralized scheduler, applies some scheduling strategy in routing the requests to the most suitable Web server. Unlike traditional parallel/distributed systems in which a centralized scheduler has full control of the system, the DNS controls only a very small fraction of the requests reaching the multiserver Web site. This peculiarity, especially in the presence of highly skewed load, makes it very difficult to achieve acceptable load balancing and avoid overloading some Web servers. This paper adapts traditional scheduling algorithms to the DNS, proposes new policies, and examines their impact under different scenarios. Extensive simulation results show the advantage of strategies that make scheduling decisions on the basis of the domain that originates the client requests and limited server state information (e.g., whether a server is overloaded or not). An initially unexpected result is that using detailed server information, especially based on history, does not seem useful in predicting the future load and can often lead to degraded performance     

Enterprise computing: the Java factor

The ubiquitous availability of Web browsers on multiple platforms and user familiarity with browser technology provide numerous advantages: a uniform interface; support for multimedia and user interaction and collaboration; a simple communication protocol that has been implemented in all major hardware and software platforms; and support by almost all vendors who package Web engines within their products. Such factors have expedited the implementation of network centric computing as a productive infrastructure for corporate environments. The addition of Java, with its ability to build cross platform application logic into a browser, gives network centric computing the potential to better meet enterprise computing needs. Because it lets users interact with the application on the client rather than the server, Java enables better utilization of both the server and the client's computational capability. Java can also provide sessions state information (for client side session control and resource management) in an otherwise stateless Web world. Besides naturally decentralizing application execution, Java makes it possible to decentralize application deployment. In large enterprises, organization wide applications such as personnel timekeeping or document routing can benefit from Java implementations. One immediate impact is a noticeable reduction of the server load during peak hours. Finally, Java enabled browsers can provide greater functionality than HTML     

Video personalization in heterogeneous and resource-constrained environments

Access to multimedia data and multimedia services is becoming increasingly common in networked mobile environments. In such environments, both the mobile client devices and multimedia servers are typically resource constrained. Moreover, the mobile client population is often heterogeneous in terms of the clients’ preferences with regard to multimedia content, the clients’ quality of service requirements and system-level resource constraints. In order to provide a resource-constrained mobile client with its desired video content, it is often necessary to personalize the requested multimedia content in a manner that satisfies simultaneously the various client-specified content preferences and the system-level resource constraints. Also, in order to simultaneously reduce the client-experienced latency, provide optimal quality of service to the clients and ensure efficient utilization of server and network resources, it is necessary to perform client request aggregation on the server end. To this end, a video personalization strategy is proposed to provide mobile, resource-constrained clients with personalized video content that is most relevant to the clients’ requests while satisfying simultaneously multiple client-side system-level resource constraints. A client request aggregation strategy is also proposed to cluster client requests with similar video content preferences and similar client-side resource constraints such that the number of requests the server needs to process and service, and the client-experienced latency are both reduced simultaneously. The primary contributions of the paper are: (1) the formulation and implementation of a Multiple-choice Multi-dimensional Knapsack Problem (MMKP)-based video personalization strategy; and (2) the design and implementation of a client request aggregation strategy based on a multi-stage clustering algorithm. Experimental results comparing the proposed MMKP-based video personalization strategy to existing 0/1 Knapsack Problem (0/1KP)-based and the Fractional Knapsack Problem (FKP)-based video personalization strategies are presented. It is observed that: (1) the proposed MMKP-based personalization strategy includes more relevant video content in response to the client’s request compared to the existing 0/1KP-based and FKP-based personalization strategies; and (2) in contrast to the 0/1KP-based and FKP-based personalization strategies which can satisfy only a single client-side resource constraint at a time, the proposed MMKP-based personalization strategy is capable of satisfying multiple client-side resource constraints simultaneously. Experimental results comparing the client-experienced latency with and without the proposed server-side client request aggregation strategy are also presented. It is shown that the proposed client request aggregation strategy reduces the mean client-experienced latency without significant reduction in the average relevance of the delivered video content and without significant deviation in the client-side resources actually consumed by the delivered video content from the client-specified resource constraints.     

Device independence and the Web

Device manufacturers, users, and authors have differing needs and expectations when it comes to Web content. Web software and hardware manufacturers naturally try to differentiate their products by supporting a special combination of capabilities, but few can expect Web authors to create content for their product alone. Users, however, do expect to access the same content from any device with similar capabilities. Even when device capabilities differ, users might still want access to an adapted version of the content. Due to device differences, the adaptation might not produce an identical presentation, but device-independence principles suggest it should be sufficiently functional to let users interact with it successfully. Web application authors cannot afford to create multiple content versions for each of the growing range of device types. Authors would rather create their content once, and adapt it to different devices-but they also want to retain control of presentation quality. Device independence is about trying to satisfy these differing needs, spanning the delivery path between author and user by way of diverse manufacturers' devices. The field's continued evolution within the broader Web standards framework aims to find solutions that are beneficial for all.     

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.     

Multimedia presentation organization and playout management using intelligent agents

This paper presents a model for organization, computation and management of automated multimedia presentations based on active multimedia segments retrieved from a multimedia information system as well as the Web. Existing multimedia presentation system is extended in such a way that its content selection component spans from local data resources to the entire Web by use of intelligent agents which associates related multimedia segments. We describe a multimedia presentation authoring environment in which a new heuristic method is introduced based on the multimedia resources selected and organization operators to apply. This method is used for the construction of a presentation graph representing an organized presentation. Once the presentation graph is constructed, we show how to obtain an event-point representation of the presentation graph. Based on event-point representation, three methods are given for playing out the constructed presentations at the presentation terminal. Presentation environments of the end-users are modeled as (i) without any constraint, (ii) with a single constraint, and (iii) with multiple constraints (one constraint for each type of multimedia segments in the organized presentation). In accordance with these limitations (i.e., without violating any of the end-user specified constraints), three methods play out any organized presentation.     

Multimedia Clip Generation From Documents for Browsing on Mobile Devices

Small displays on mobile handheld devices, such as personal digital assistants (PDAs) and cellular phones, are the bottlenecks for usability of most content browsing applications. Generally, conventional content such as documents and Web pages need to be modified for effective presentation on mobile devices. This paper proposes a novel visualization for documents, called multimedia thumbnails, which consists of text and image content converted into playable multimedia clips. A multimedia thumbnail utilizes visual and audio channels of small portable devices as well as both spatial and time dimensions to communicate text and image information of a single document. The proposed algorithm for generating multimedia thumbnails includes 1) a semantic document analysis step, where salient content from a source document is extracted; 2) an optimization step, where a subset of this extracted content is selected based on time, display, and application constraints; and 3) a composition step, where the selected visual and audible document content is combined into a multimedia thumbnail. Scalability of MMNails that allows generation of multimedia clips of various lengths is also described. A user study is presented that evaluates the effectiveness of the proposed multimedia thumbnail visualization.     

Congruent patterns of outsourcing capabilities: A bilateral perspective

Despite the extensive proliferation of Information Technology Outsourcing (ITO), firms often obtain unsatisfactory outsourcing outcomes due to the lack of appropriate outsourcing capabilities of a client or their vendor. ITO clients strive to enhance outsourcing performance by establishing their own outsourcing capabilities as well as contracting with capable vendors to meet their strategic needs. Thus, for the success of an ITO project, it is imperative to find an effective combination of complementary outsourcing capabilities on both sides. However, knowledge of how to identify and develop a set of appropriate outsourcing capabilities of both client and vendor has yet to be developed. This study aims to fill this knowledge gap by elaborating on the configurational mechanisms of outsourcing capabilities from a bilateral perspective, which explicate how multiple types of client and vendor outsourcing capabilities combine into configurations simultaneously to produce high ITO performance. First, based on the ITO literature, we develop a conceptual framework that identifies three key types of outsourcing capabilities. Then, with the matched dataset collected from a client and their vendor, we conduct a fuzzy-set qualitative comparative analysis (fsQCA), which is a set-theoretic configurational method to investigate the systemic and holistic interdependencies among key outsourcing capabilities that produce high outsourcing performance. On the basis of the conceptual framework and empirical findings, we present four viable propositions to build configurations of client and vendor ITO capabilities that can achieve ITO success with theoretical and practical implications.     

WESONet: Applying semantic web technologies and collaborative tagging to multimedia web information systems

The publication of different media types, like images, audio and video in the World Wide Web is getting more importance each day. However, searching and locating content in multimedia sites is challenging. In this paper, we propose a platform for the development of multimedia web information systems. Our approach is based on the combination between semantic web technologies and collaborative tagging. Producers can add meta-data to multimedia content associating it with different domain-specific ontologies. At the same time, users can tag the content in a collaborative way. The proposed system uses a search engine that combines both kinds of meta-data to locate the desired content. It will also provide browsing capabilities through the ontology concepts and the developed tags.     

Video transcoding: an overview of various techniques and research issues

One of the fundamental challenges in deploying multimedia systems, such as telemedicine, education, space endeavors, marketing, crisis management, transportation, and military, is to deliver smooth and uninterruptible flow of audio-visual information, anytime and anywhere. A multimedia system may consist of various devices (PCs, laptops, PDAs, smart phones, etc.) interconnected via heterogeneous wireline and wireless networks. In such systems, multimedia content originally authored and compressed with a certain format may need bit rate adjustment and format conversion in order to allow access by receiving devices with diverse capabilities (display, memory, processing, decoder). Thus, a transcoding mechanism is required to make the content adaptive to the capabilities of diverse networks and client devices. A video transcoder can perform several additional functions. For example, if the bandwidth required for a particular video is fluctuating due to congestion or other causes, a transcoder can provide fine and dynamic adjustments in the bit rate of the video bitstream in the compressed domain without imposing additional functional requirements in the decoder. In addition, a video transcoder can change the coding parameters of the compressed video, adjust spatial and temporal resolution, and modify the video content and/or the coding standard used. This paper provides an overview of several video transcoding techniques and some of the related research issues. We introduce some of the basic concepts of video transcoding, and then review and contrast various approaches while highlighting critical research issues. We propose solutions to some of these research issues, and identify possible research directions.     

Modeling languages for business processes and business rules: A representational analysis

Process modeling and rule modeling languages are both used to document organizational policies and procedures. To date, their synergies and overlap are under-researched. Understanding the relationship between the two modeling types would allow organizations to maximize synergies, avoid content duplication, and thus reduce their overall modeling effort. In this paper, we use the Bunge–Wand–Weber (BWW) representation theory to compare the representation capabilities of process and rule modeling languages. We perform a representational analysis of four rule modeling specifications: The Simple Rule Markup Language (SRML), the Semantic Web Rules Language (SWRL), the Production Rule Representation (PRR), and the Semantics of Business Vocabulary and Business Rules (SBVR) specification. We compare their BWW representation capabilities with those of four popular conceptual process modeling languages. In our analysis, we focus on the aspects of maximum ontological completeness and minimum ontological overlap. The outcome of this study shows that no single language is internally complete with respect to the BWW representation model. We also show that a combination of two languages, in particular SRML and BPMN, appears to be better suited for combined process and rule modeling than any of these modeling languages used independently.     

SIP IP多媒体通信系统的地址翻译

对SIPIP多媒体通信系统进行了简单的介绍。详细分析了DNS系统中的SRV和NAPTR两种资源记录及其使用方法。重点描述了SIPIP多媒体通信系统中的地址翻译过程,包括客户端的地址翻译和服务器端的地址翻译。     

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