Distributed Syst. Eng.最新文献_第6页

QoS management in a World Wide Web environment which supports continuous media 支持连续媒体的万维网环境中的QoS管理

Distributed Syst. Eng. Pub Date : 1997-03-01 DOI: 10.1088/0967-1846/4/1/005

M. Fry, A. Seneviratne, A. Vogel, V. Witana

{"title":"QoS management in a World Wide Web environment which supports continuous media","authors":"M. Fry, A. Seneviratne, A. Vogel, V. Witana","doi":"10.1088/0967-1846/4/1/005","DOIUrl":"https://doi.org/10.1088/0967-1846/4/1/005","url":null,"abstract":"Until recently the World Wide Web (WWW) and associated browser technologies have provided no support for the delivery of continuous media in real time. Instead, files have been down-loaded completely and then played back. There are now some systems available that provide support for streaming of audio and/or video between WWW servers and clients. However the Internet comprises a vast range of networks and end systems with different characteristics, which together determine the level of continuous media service quality that can be supported for a given connection. A quality of service (QoS) model is required that will encompass the heterogeneity of the Internet environment. In this paper we present our approach to delivering continuous media in WWW environments, based on a model of end-to-end QoS management. We have developed an experimental implementation that permits real-time delivery of audio and video within the WWW. Significantly our implementation incorporates end-to-end QoS negotiation and QoS adaptation, which adjusts the delivery stream to match prevailing network and system conditions. We describe the design and implementation of our WWW-based QoS model. We then discuss some issues arising from our experience, including a proposal for future work based on a more open, object oriented architecture.","PeriodicalId":404872,"journal":{"name":"Distributed Syst. Eng.","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114398765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

A three-level atomicity model for decentralized workflow management systems 分布式工作流管理系统的三层原子性模型

Distributed Syst. Eng. Pub Date : 1996-12-01 DOI: 10.1088/0967-1846/3/4/004

I. Ben-Shaul, G. Heineman

引用次数: 4

Correctness issues in workflow management 工作流管理中的正确性问题

Distributed Syst. Eng. Pub Date : 1996-12-01 DOI: 10.1088/0967-1846/3/4/002

M. Kamath, K. Ramamritham

{"title":"Correctness issues in workflow management","authors":"M. Kamath, K. Ramamritham","doi":"10.1088/0967-1846/3/4/002","DOIUrl":"https://doi.org/10.1088/0967-1846/3/4/002","url":null,"abstract":"Workflow management is a technique to integrate and automate the execution of steps that comprise a complex process, e.g., a business process. Workflow management systems (WFMSs) primarily evolved from industry to cater to the growing demand for office automation tools among businesses. Coincidentally, database researchers developed several extended transaction models to handle similar applications. Although the goals of both the communities were the same, the issues they focused on were different. The workflow community primarily focused on modelling aspects to accurately capture the data and control flow requirements between the steps that comprise a workflow, while the database community focused on correctness aspects to ensure data consistency of sub-transactions that comprise a transaction. However, we now see a confluence of some of the ideas, with additional features being gradually offered by WFMSs. This paper provides an overview of correctness in workflow management. Correctness is an important aspect of WFMSs and a proper understanding of the available concepts and techniques by WFMS developers and workflow designers will help in building workflows that are flexible enough to capture the requirements of real world applications and robust enough to provide the necessary correctness and reliability properties. We first enumerate the correctness issues that have to be considered to ensure data consistency. Then we survey techniques that have been proposed or are being used in WFMSs for ensuring correctness of workflows. These techniques emerge from the areas of workflow management, extended transaction models, multidatabases and transactional workflows. Finally, we present some open issues related to correctness of workflows in the presence of concurrency and failures.","PeriodicalId":404872,"journal":{"name":"Distributed Syst. Eng.","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133126913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 63

Guest Editor's introduction 特邀编辑介绍

Distributed Syst. Eng. Pub Date : 1996-12-01 DOI: 10.1088/0967-1846/3/4/001

Panos K. Chrysanthis

引用次数: 2

Scheduling workflows by enforcing intertask dependencies 通过执行任务间依赖关系来调度工作流

Distributed Syst. Eng. Pub Date : 1996-12-01 DOI: 10.1088/0967-1846/3/4/003

P. Attie, Munindar P. Singh, E. Emerson, A. Sheth, M. Rusinkiewicz

{"title":"Scheduling workflows by enforcing intertask dependencies","authors":"P. Attie, Munindar P. Singh, E. Emerson, A. Sheth, M. Rusinkiewicz","doi":"10.1088/0967-1846/3/4/003","DOIUrl":"https://doi.org/10.1088/0967-1846/3/4/003","url":null,"abstract":"Workflows are composite activities that can be used to support and automate multisystem applications involving humans, heterogeneous databases and legacy systems. The traditional atomic transaction model, successful for centralized and homogeneous applications, is not suitable for supporting such workflows. Intertask dependencies, which are conditions involving events and dependencies among workflow tasks, are used to specify the coordination requirements among the workflow tasks and are a central component of most workflow models. They form a basis for developing a uniform formal framework for workflows, which is a key contribution of this work. In this paper, we formalize intertask dependencies using temporal logic. This involves event attributes, which are needed to determine whether a dependency is enforceable and to properly schedule events. Each dependency is represented internally as a finite state automaton that captures the computations that satisfy the given dependency. Sets of automata are combined into a scheduler that produces global computations satisfying all relevant dependencies, thus enacting the given workflow. This algorithm is rigorously proved correct; it has been implemented.","PeriodicalId":404872,"journal":{"name":"Distributed Syst. Eng.","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127676222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 49

Workflow management systems on top of OSF DCE and OMG CORBA 基于OSF DCE和OMG CORBA的工作流管理系统

Distributed Syst. Eng. Pub Date : 1996-12-01 DOI: 10.1088/0967-1846/3/4/005

Alexander Schill, C. Mittasch

引用次数: 3

Prospects for Internet technology 互联网技术展望

Distributed Syst. Eng. Pub Date : 1996-12-01 DOI: 10.1088/0967-1846/4/2/002

B. Carpenter, J. Crowcroft

引用次数: 2

The evolution towards flexible workflow systems 向灵活工作流系统的演变

Distributed Syst. Eng. Pub Date : 1996-12-01 DOI: 10.1088/0967-1846/3/4/007

G. Nutt