A number of distributedapplications require communication services with quality of service (QoS) guarantees. Building global-scale distributed systems with predictable properties is one of the great challenges for co...
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A number of distributedapplications require communication services with quality of service (QoS) guarantees. Building global-scale distributed systems with predictable properties is one of the great challenges for computer systems engineering in the new century. Work undertaken within the Internet Engineering Task Force has led to the definition of novel architectural models for the Internet with QoS support. According to these models, the network has to be appropriately configured in order to provide applications with the required performance guarantees. In next-generation networks, enabling applications to interact with the underlying QoS services is of primary importance. Hence, several special-purpose application programming interfaces (APIs) have been defined to let applications negotiate QoS parameters across QoS-capable networks. However, so far, none of these APIs are available in different operating environments. We believe that such features should be embedded in programming environments for distributedapplications. In this work we present how we included QoS control features in Tcl, a programming language that has been widely adopted for the development of distributed multimedia applications. Our work has led to the implementation of QTcl, an extended Tcl interpreter that provides programmers with a new set of primitives, in full compliance with the standard SCRAM programming interface for the RSVP protocol. QTcl in highly portable, in that it enables standard QoS negotiation to be performed in a seamless fashion on the most common operating systems. Copyright (C) 2003 John Wiley Sons, Ltd.
The Java programming language has been projected as a universal language for the development of distributedapplications. Unfortunately, the project of such applications using Java is a complex task, requiring the aut...
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The Java programming language has been projected as a universal language for the development of distributedapplications. Unfortunately, the project of such applications using Java is a complex task, requiring the author to be a specialist in this language. This paper presents MUSE, a graphical environment for the conception of interactive multimediaapplications. The sophisticated user interface of this environment and its new high-level authoring model allow the creation of complex applications in a fast and intuitive way. Due to the large expressiveness of the model, the author may create multimediaapplications with logical and temporal inconsistencies. For this reason, the environment also allows the automatic generation of E-LOTOS specifications, which can be used to analyze and to verify the logical and temporal restrictions defined by the author. After obtaining the complete and correct description of the multimedia application, the environment generates the corresponding Java application.
distributedmultimedia (MM) applications such as video-on-demand and teleconferencing provide services with different quality of service (QoS) requirements. Hence, the user should be able to negotiate the desired QoS ...
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distributedmultimedia (MM) applications such as video-on-demand and teleconferencing provide services with different quality of service (QoS) requirements. Hence, the user should be able to negotiate the desired QoS depending on his/her needs, the end-system characteristics and his/her financial capacity. In response to a service request with the desired QoS, most QoS negotiation approaches return an acceptance or a simple rejection of the request. More specifically, they provide the user only with the QoS that can be supported at the time the request is made and assume that the service is requested for indefinite duration. This paper describes work on a new QoS negotiation approach with future reservations (NAFUR) that decouples the starting time of the service from the time the service request is made and requires that the duration of the requested service must be specified. NAFUR allows to compute the QoS that can be supported for the time the service request is made, and at certain later times carefully chosen. As an example, if the requested QoS cannot be supported for the time the service request is made, the proposed approach allows to compute the earliest time, when the user can start the service with the desired QoS. NAFUR will help to increase (a) the flexibility of the system by providing the user with more choices, and (b) the system resource utilization, and the availability of the system, by encouraging the sharing of the resources, e.g. multicast for video-on-demand systems. Furthermore, it provides the flexibility to incorporate (a) a range of resource reservation schemes and scheduling policies, and (b) a range of new system component technologies. (C) 1998 Elsevier Science B.V.
In this paper, we introduce an XML-based hierarchical QoS markup language, called HQML, to enhance distributed multimedia applications on the World Wide Web (WWW) with quality of service (QoS) capability. The design o...
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In this paper, we introduce an XML-based hierarchical QoS markup language, called HQML, to enhance distributed multimedia applications on the World Wide Web (WWW) with quality of service (QoS) capability. The design of HQML is based on two observations: (1) the absence of a systematic QoS specification language, that can be used by distributed multimedia applications on the WWW to utilize the state-of-the-art QoS management technology and (2) the power and popularity of XML to deliver richly structured contents over the Web. HQML allows distributed multimedia applications to specify all kinds of application-specific QoS policies and requirements. During runtime, the HQML Executor translates the HQML file into desired data structures and cooperates with the QoS proxies that assist applications in end-to-end QoS negotiation, setup and enforcement. In order to make QoS services tailored toward user preferences and meet the challenges of uncertainty in the distributed heterogeneous environments, the design of HQML is featured as interactive and flexible. In order to allow application developers to create HQML specifications correctly and easily, we have designed and developed a unified visual QoS programming environment, called QoSTalk. In QoSTalk, we adopt a grammatical approach to perform consistency check on the visual QoS specifications and generate HQML files automatically. Finally, we introduce the distributed QoS compiler, which performs the automatic mappings between application- and resource-level QoS parameters to relieve the application developer of the burden of dealing with low-level QoS specifications. (C) 2002 Elsevier Science Ltd. All rights reserved.
Narnia is middleware that helps programmers build multimedia communication services. This middleware uses a collection of familiar programming abstractions-including events, event handlers, resources, sessions, and us...
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ISBN:
(纸本)0769518575
Narnia is middleware that helps programmers build multimedia communication services. This middleware uses a collection of familiar programming abstractions-including events, event handlers, resources, sessions, and user roles-to provide both a service development environment and a service execution environment. The run-time environment-the Narnia virtual machine-provides means for creating, transmitting, and consuming events as well as means for creating, loading, and executing sessions and event handlers. The Narnia middleware has served as the development and execution platform for a few applications-including an audio/video chat application and a SIP proxy simulator. The paper reports on how well these applications handle various user request workloads. These early system performance measurements indicate the effectiveness of Narnia in supporting development and deployment of scalable network multimedia services.
Multicast distribution of multimedia streams is an important component of many existing and future networked services. These services are characterized by the integrated processing of different media types, such as au...
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ISBN:
(纸本)0769507816
Multicast distribution of multimedia streams is an important component of many existing and future networked services. These services are characterized by the integrated processing of different media types, such as audio and video. Often, different multimedia streams must be played out in a synchronized way. Due to the asynchronous nature of networks, some problems can disrupt synchronization such as delay jitter and different initial playback times. In this paper, we propose a method consisting of intra-stream and inter-client synchronization mechanisms. It allows different members of a multicast group to playback media units at the same time and in a continuous manner. The mechanism can be used in networks having unknown delay bounds. It allows to receivers to be synchronized far media unit playbacks. To do this, we use feedback messages to the source and buffer management. However, there is no assumption about clock synchronization and messages are not time-stamped.
This paper presents an algorithm to control QoS for distributed multimedia applications. The algorithm approaches the problem in an integrated way solving both the problems of the network bandwidth and the load at the...
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ISBN:
(纸本)0819428604
This paper presents an algorithm to control QoS for distributed multimedia applications. The algorithm approaches the problem in an integrated way solving both the problems of the network bandwidth and the load at the workstations. It interacts with the applications by an abstract sequence to describe values for QoS that are more meaningful to application programmers than the low-level entities such as cell loss rate, throughput, etc. Some experimental results of the algorithm are presented.
Needs of multimedia systems evolved due to the evolution of their architecture which is now distributed into heterogeneous contexts like the Internet network. A critical issue lies in the fact that they handle, proces...
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ISBN:
(纸本)9789639799165
Needs of multimedia systems evolved due to the evolution of their architecture which is now distributed into heterogeneous contexts like the Internet network. A critical issue lies in the fact that they handle, process, and transmit multimedia data. This data integrates several properties which should be considered since it holds a considerable part of its semantic, e.g. the lips synchronization in a video. In this paper, we focus on the definition of a basic abstraction for describing and modeling data in multimedia systems by taking into account their properties. This abstraction is proposed with synchronization policies to ensure synchronous transport of multimedia data. We use it in a component model that we develop for the design and deployment of distributedmultimedia systems.
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