一种基于XML的同步超媒体文档模型研究与实现
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摘要
WWW自发展以来，同步超媒体信息的控制始终是一个难题，也是一个研究热点。为了解决网络上的超媒体表现的同步控制、实时传输和计时超链等问题，本文采用超文本技术和多媒体技术相结合的超媒体技术，应用可扩展标记语言这个新技术来描述同步超媒体文档模型，解决了媒体的异种格式的统一描述和文档的开放性；实现了异构系统之间的交互性、可移植性和资源的共享复用；应用同步多媒体集成语言这个新技术来创建该模型的同步超媒体文档，解决了超媒体文档的实时交互、复用和检索。实现了满足超媒体同步控制中的多种通信模式兼容、文档结构开放、实时交互等的性能。
本文首先简要介绍了超媒体技术及其同步机制，阐述了有关超媒体的基本要素，详细描述超媒体文档模型的结构，形式化定义了超媒体文档模型，分析了超媒体文档的结构特性；其次，对超媒体的同步机制进行综述，详细分析了XML技术及其子集SMIL技术，提出基于XML的同步超媒体文档模型并用UML技术建构了该模型的XML课件文档模型，描述了同步超媒体课件文档之间的时间同步关系和空间编排关系；最后，分析了该课件文档模型的结构特性和建模方法，设计并实现了以该课件文档模型为核心的同步超媒体实时教学系统的原型，分析了该系统的通信结构和逻辑结构，描述了该系统的基于XML模式的对象模型，对该系统原形的一个应用实例进行测试。测试的结果表明该系统比传统网络教学系统具有较强的自适应能力，能较好地解决网络中超媒体文档的实时传输的带宽问题和同步控制问题，达到预期的效果。
本文研究并实现了同步超媒体文档模型，它是基于XML的数据模型和建模方法，使构建的同步超媒体文档模型具有算法简单、创作方便、易于实现、网络传输额外开销小和较好的QoS质量，具有相当广阔的应用前景。但是，对超媒体文档的动态建模和对超媒体资源库的实时更新目前还没有取得应用，这将是以后的进一步的研究工作。
Since WWW developed, To control synchronized hypermedia information is always a problem, and a research hotspot too. In order to resolve the hypermedia representation synchronized control, real-time transmission and overtime hyperlink etc problem on the network, In this paper adopt the hypertext technology and multimedia technology combine into hypermedia technology, and apply the new technic XML to describe synchronized hypermedia document model,It settled the media heterogeneity format unification description and open of document ; It implemented the heterogeneity system interactive^ transplantable and resource share and resuse; It apply synchronized multimedia integration language establish its synchronized hypermedia document of model, and settled the hypermedia document real-time interactive, resuse and retrive.lt implemented to satisfy the hypermedia in the synchronized control multi-communication mode compatible, document structure open, real-time interactive etc performance.
Firstly, we brief introduced hypermedia technology and the synchronized mechanism in this paper, we expatiated respect hypermedia basic factor, particular described hypermedia document model structure, formalization defined hypermedia document model, analyzed hypermedia document structure characteristic; Secondly, we summarized hypermedia synchronized mechanism, particularly analyzed XML thchnique and its subset SMIL technique, We put forward XML-based synchronized hypermedia document model and with the UML technique erected the XML courseware document model, We described synchronized hypermedia courseware document relation of time synchronization and space layout; Finally, we analyzed the courseware document model srucuture and modeling
method, designed and implemented with the courseware document model for the core into synchronized hypermedia real-time education system prototype, We analyzed the system communiction structure and logic structure, described the system base on the XML schema object model, Tested the system, the result indicated the system more adaptation than the tradition elearning system, preferably settled the hypermedia document real-time transmission bandwidth and synchronized control problem, reached anticipative purpose.
We studied and implemented synchronized hypermedia document model in the paper, It is XML-based data model and modeling method, Constructed the synchronized hypermedia document model have algorithm briefnessN produce facility , tend to implementation , little network transmit superfluity overhead and preferably QoS quality, it has quite vastitude application foreground. But it could not design the dynamic modeling for the courseware document and it could take out application for the real-time update and enrich the courseware resource library now. It will be more research work from now on.
本文首先简要介绍了超媒体技术及其同步机制，阐述了有关超媒体的基本要素，详细描述超媒体文档模型的结构，形式化定义了超媒体文档模型，分析了超媒体文档的结构特性；其次，对超媒体的同步机制进行综述，详细分析了XML技术及其子集SMIL技术，提出基于XML的同步超媒体文档模型并用UML技术建构了该模型的XML课件文档模型，描述了同步超媒体课件文档之间的时间同步关系和空间编排关系；最后，分析了该课件文档模型的结构特性和建模方法，设计并实现了以该课件文档模型为核心的同步超媒体实时教学系统的原型，分析了该系统的通信结构和逻辑结构，描述了该系统的基于XML模式的对象模型，对该系统原形的一个应用实例进行测试。测试的结果表明该系统比传统网络教学系统具有较强的自适应能力，能较好地解决网络中超媒体文档的实时传输的带宽问题和同步控制问题，达到预期的效果。
本文研究并实现了同步超媒体文档模型，它是基于XML的数据模型和建模方法，使构建的同步超媒体文档模型具有算法简单、创作方便、易于实现、网络传输额外开销小和较好的QoS质量，具有相当广阔的应用前景。但是，对超媒体文档的动态建模和对超媒体资源库的实时更新目前还没有取得应用，这将是以后的进一步的研究工作。
Since WWW developed, To control synchronized hypermedia information is always a problem, and a research hotspot too. In order to resolve the hypermedia representation synchronized control, real-time transmission and overtime hyperlink etc problem on the network, In this paper adopt the hypertext technology and multimedia technology combine into hypermedia technology, and apply the new technic XML to describe synchronized hypermedia document model,It settled the media heterogeneity format unification description and open of document ; It implemented the heterogeneity system interactive^ transplantable and resource share and resuse; It apply synchronized multimedia integration language establish its synchronized hypermedia document of model, and settled the hypermedia document real-time interactive, resuse and retrive.lt implemented to satisfy the hypermedia in the synchronized control multi-communication mode compatible, document structure open, real-time interactive etc performance.
Firstly, we brief introduced hypermedia technology and the synchronized mechanism in this paper, we expatiated respect hypermedia basic factor, particular described hypermedia document model structure, formalization defined hypermedia document model, analyzed hypermedia document structure characteristic; Secondly, we summarized hypermedia synchronized mechanism, particularly analyzed XML thchnique and its subset SMIL technique, We put forward XML-based synchronized hypermedia document model and with the UML technique erected the XML courseware document model, We described synchronized hypermedia courseware document relation of time synchronization and space layout; Finally, we analyzed the courseware document model srucuture and modeling
method, designed and implemented with the courseware document model for the core into synchronized hypermedia real-time education system prototype, We analyzed the system communiction structure and logic structure, described the system base on the XML schema object model, Tested the system, the result indicated the system more adaptation than the tradition elearning system, preferably settled the hypermedia document real-time transmission bandwidth and synchronized control problem, reached anticipative purpose.
We studied and implemented synchronized hypermedia document model in the paper, It is XML-based data model and modeling method, Constructed the synchronized hypermedia document model have algorithm briefnessN produce facility , tend to implementation , little network transmit superfluity overhead and preferably QoS quality, it has quite vastitude application foreground. But it could not design the dynamic modeling for the courseware document and it could take out application for the real-time update and enrich the courseware resource library now. It will be more research work from now on.
引文
[1] G Rossi, D Schwabe, A Garrido. Pattern Systems for Hypermedia Proc. Of PLOP' 971997. Availableathttp://www.inf. puc~rio, br/~schwabe/papers/Plop97.bdf[EB/OL].
[2] F. Halasz and M. Schwartz.The Dexter Hypertext Reference Model. Communications of the ACM[J],37(2):30~39, February 1994.
[3] D German, D Cowan, Towards a Unified Catalog of Hypermedia Design Patterns, 33rd Hawaii International Conference on System Sciences (HICSS2000),Availableathttp://dlib. computer.org/conferen/hicss/04 93/pdf/04936067.pdt[EB/OL].
[4] Escobar J, Deutsch D, Partridge C. Flow Synchronization Protocol. CLOBECOM 92[C].Orlando, Florida:IEEE Computer Society, 1992.1381～1387.
[5] Ferrari D. Delay Jitter Control Scheme for Packe-Switching Internet-Works[J].Computer Communications. 1992,15(6): 367～373.
[6] Rangan P.V, Ramanathan S, Vin H M, etal. Technique for Multimedia Synchronization in Network File Systems[J].Computer Commun, 1993,16(3):168～176.
[7] Little T.D.C, Ghafoor A. Synchronization and Storage. Models for Multimedia Object[J].IEEE JSAC, 1990,8(3):413～427.
[8] Huang C.M, Wang C. Synchronization Interactive Multimedia Presentations[J].IEEE Multimedia, 1998,5(4):44～61.
[9] Synchronized Multimedia Working Group of W3C. Synchronized Multimedia Integration Language (SMIL) 2.0 Specification. http://www.w3.org/TR/smil20, August 2001.
[10] Suzanne Hoffman, Elaboration Theory and Hypermedia: Is there a link? Educational Technology[J], 1997, 1～2(37).
[11] Susanne Boll and Wolfgang Klas. ZYX, a Multimedia Document Model for Reuse and Adaption of Multimedia Content. IEEE Transaction on Knowledge and Data Engineering[J], DS-8Special Issue, 13(3):361～382,May/June 2001.
[12] 田沧海．支持多介质数据库的NF2方法．[J]计算机科学，1992，1：67～71．
[13] Frank G Halasz. Reflections on note Cards:Seven issues for the next generation of hypermedia systems. Communications of the ACM[J], 1988, 31(7):836～852.
[14] 余盛可。超文本形式化模型研究。[J]计算机研究与发展。Vol．32 No．3 Mar.1995：31～50．
[15] A. Celentano and O. Gaggi. Synchronization Model for Hypermedia Document Navigation. In ACM Symposium on Applied Computing(SAC2000), Como, Italy, March2000:585～591,.
[16] 余盛可．H-网：一个基于PETRI网的超文本形式模型．[J]计算机学报．1995，Vol．18，No．7：521～531．
[17] 徐海燕，周学海，倪劲峰等．基于结构特性的超媒体模型．[J]计算机研究与发展．2001，Vol．38，No.4：444～450．
[18] 李春光，温涛．超媒体同步模型研究．[J]小型微型计算机系统．Vol．21，No.3，Mar2000：325～328．
[19] Patrick Senac, michel Diaz. Modeling logical and temporal synchronization in hypermedia system.[J]IEEE Journal on Selected Areas in Communications 1996, Vol. 14, No.1,84～103.
[20] 老松杨，胡晓峰，吴玲达等．一种超媒体表现的时间合成模型．[J]小型微型计算机系统．Vol．19，No.3，Mar．1998：8～13．
[21] 张苓．基于Petri网的超媒体形式化模型．[J]武汉大学学报．Vol．45，No．1，1999，45～48．
[22] Ombretta Oaggi," Synchronized Hypermedia Documents:a Model and its Applications",Department of Computer Science University of Bologna Mura Anteo Zamboni 740127 Bologna(Italy)Technical Report[C] UBLCS-2003-05, March 2003.
[23] Shepherd D, Salmony M. Extending OSI to Support Synchronization Required by Multimedia Application [J]Computer Communications. 1990,13(7):399～406.
[24] L. F. G. Soares, R. F. Rodrigues, and D. C. Muchaluat Saade. Modeling, Authoring and Formatting Hypermedia Documents in the HyperProp System. Multimedia Systems[J], 8(2):118～134, 2000.
[25] http://www.w3. org/tr/1998/rec-xml-19980210, Extensible Markup Language(XML 1.0)[OL].
[26] 瞿裕忠，张剑锋，陈峥等．XML语言及相关技术综述．[J]计算机工程．Vol．26，No.12，Dec2000，4～30．
[27] Qu Changtao, etal. Collaborative courseware authoring and pubilshing based on WebDZV, XML, and XSLT. EUROCON' 2001. Intl. Conf. on Trends in Communications. TechnicalProgram, Proceedings(Cat. No. 01EX439). [J]IE EE. Part vol. 2,2001,266～269 vol. 2. Piscataway, NJ, USA.
[28] W3C. Document Object Model(DOM)Level 1 Specification Version 1.0. W3Crecommendation, 1998-10-01. http://www.w3c.org/TR/1998/REC-D OM-Level-1-19981001/,[OL].
[29] Synchronized Multimedia Integration Language. W3C Working Draft 2,1998.2, http://www.w3c.org/AudioVideo.[OL]
[30] Synchronized Multimedia Working Group of W3C. Synchronized Mu].timedia Integration Language (SMIL) 2.0 Specification. http://www.w3.org/TR/smil20,[OL] August 2001.
[31] 张平，蒋凡．在网上用SMIL实现多媒体同步．计算机应用．2001年5月，第21卷(5)：55～56．
[32] 刘斌，杜欢等．基于XML的同步多媒体课件制作系统．小型微型计算机系统．2000年7月，第21卷第七期：779～781．
[33] 鄢红国，姚慧广，基于UML的远程教学系统的设计，[J]计算机与现代化，2002．8：59～60．
[34] 徐静，刘传文，用UML建模XML应用的研究及实现．[J]微型机与应用．2002
年第6期：58～60．
[35] 陈福集，杨善林；基于XML的个性化课件开发环境研究，[J]计算机工程，2003年2月，29(2)：221～230．
[36] 刘煜海，陆蕙西等．流式媒体同步集成技术在远程教学信息系统中的应用．计算机工程[J]．2001年1月．第27卷第1期．109～111．
[37] 李拥军，王惟言等．基于多agent网际实时教学系统的研究和实现．[J]计算机工程与应用．2003．18，181～183．
[38] 黄发国，应时，丰波等，用UML为XML Schema建模。[J]计算机应用，2001，21：19～21．
[39] 曹忠升，刘会志，J2EE平台构建远程教学答疑系统，[J]计算机辅助工程，2002，6(2)：43～47．
[40] 杨存东，申瑞民，张同珍．基于IMS规范的个性Web课件制作模型研究及实现，[J]小型微型计算机系统，2002，25(5)：540～543．
[41] W3C. XSL Transformations(XSLT)Version 1.0. W3C Recommendation 16 November 1999. http://www.w3. org/TR/xslt
[42] W3C. XML Path Language(Xpath) Version 1.0. W3Crecommendation 16 November 1999. http://www.w3. org/TR/xpath.
[43] W3C. XML Lingking Language(Xlink)Version 1.0. W3C Recommendation 27 June 2001. http://www.w3.org/TR/xlink/.
[44] W3C.Document Object Model(DOM)Level 2 Core Specification Version1.0. W3C Recommendation 13 November, 2000. http://www.w3.org/TR/DOM-Level-2-Core.
[2] F. Halasz and M. Schwartz.The Dexter Hypertext Reference Model. Communications of the ACM[J],37(2):30~39, February 1994.
[3] D German, D Cowan, Towards a Unified Catalog of Hypermedia Design Patterns, 33rd Hawaii International Conference on System Sciences (HICSS2000),Availableathttp://dlib. computer.org/conferen/hicss/04 93/pdf/04936067.pdt[EB/OL].
[4] Escobar J, Deutsch D, Partridge C. Flow Synchronization Protocol. CLOBECOM 92[C].Orlando, Florida:IEEE Computer Society, 1992.1381～1387.
[5] Ferrari D. Delay Jitter Control Scheme for Packe-Switching Internet-Works[J].Computer Communications. 1992,15(6): 367～373.
[6] Rangan P.V, Ramanathan S, Vin H M, etal. Technique for Multimedia Synchronization in Network File Systems[J].Computer Commun, 1993,16(3):168～176.
[7] Little T.D.C, Ghafoor A. Synchronization and Storage. Models for Multimedia Object[J].IEEE JSAC, 1990,8(3):413～427.
[8] Huang C.M, Wang C. Synchronization Interactive Multimedia Presentations[J].IEEE Multimedia, 1998,5(4):44～61.
[9] Synchronized Multimedia Working Group of W3C. Synchronized Multimedia Integration Language (SMIL) 2.0 Specification. http://www.w3.org/TR/smil20, August 2001.
[10] Suzanne Hoffman, Elaboration Theory and Hypermedia: Is there a link? Educational Technology[J], 1997, 1～2(37).
[11] Susanne Boll and Wolfgang Klas. ZYX, a Multimedia Document Model for Reuse and Adaption of Multimedia Content. IEEE Transaction on Knowledge and Data Engineering[J], DS-8Special Issue, 13(3):361～382,May/June 2001.
[12] 田沧海．支持多介质数据库的NF2方法．[J]计算机科学，1992，1：67～71．
[13] Frank G Halasz. Reflections on note Cards:Seven issues for the next generation of hypermedia systems. Communications of the ACM[J], 1988, 31(7):836～852.
[14] 余盛可。超文本形式化模型研究。[J]计算机研究与发展。Vol．32 No．3 Mar.1995：31～50．
[15] A. Celentano and O. Gaggi. Synchronization Model for Hypermedia Document Navigation. In ACM Symposium on Applied Computing(SAC2000), Como, Italy, March2000:585～591,.
[16] 余盛可．H-网：一个基于PETRI网的超文本形式模型．[J]计算机学报．1995，Vol．18，No．7：521～531．
[17] 徐海燕，周学海，倪劲峰等．基于结构特性的超媒体模型．[J]计算机研究与发展．2001，Vol．38，No.4：444～450．
[18] 李春光，温涛．超媒体同步模型研究．[J]小型微型计算机系统．Vol．21，No.3，Mar2000：325～328．
[19] Patrick Senac, michel Diaz. Modeling logical and temporal synchronization in hypermedia system.[J]IEEE Journal on Selected Areas in Communications 1996, Vol. 14, No.1,84～103.
[20] 老松杨，胡晓峰，吴玲达等．一种超媒体表现的时间合成模型．[J]小型微型计算机系统．Vol．19，No.3，Mar．1998：8～13．
[21] 张苓．基于Petri网的超媒体形式化模型．[J]武汉大学学报．Vol．45，No．1，1999，45～48．
[22] Ombretta Oaggi," Synchronized Hypermedia Documents:a Model and its Applications",Department of Computer Science University of Bologna Mura Anteo Zamboni 740127 Bologna(Italy)Technical Report[C] UBLCS-2003-05, March 2003.
[23] Shepherd D, Salmony M. Extending OSI to Support Synchronization Required by Multimedia Application [J]Computer Communications. 1990,13(7):399～406.
[24] L. F. G. Soares, R. F. Rodrigues, and D. C. Muchaluat Saade. Modeling, Authoring and Formatting Hypermedia Documents in the HyperProp System. Multimedia Systems[J], 8(2):118～134, 2000.
[25] http://www.w3. org/tr/1998/rec-xml-19980210, Extensible Markup Language(XML 1.0)[OL].
[26] 瞿裕忠，张剑锋，陈峥等．XML语言及相关技术综述．[J]计算机工程．Vol．26，No.12，Dec2000，4～30．
[27] Qu Changtao, etal. Collaborative courseware authoring and pubilshing based on WebDZV, XML, and XSLT. EUROCON' 2001. Intl. Conf. on Trends in Communications. TechnicalProgram, Proceedings(Cat. No. 01EX439). [J]IE EE. Part vol. 2,2001,266～269 vol. 2. Piscataway, NJ, USA.
[28] W3C. Document Object Model(DOM)Level 1 Specification Version 1.0. W3Crecommendation, 1998-10-01. http://www.w3c.org/TR/1998/REC-D OM-Level-1-19981001/,[OL].
[29] Synchronized Multimedia Integration Language. W3C Working Draft 2,1998.2, http://www.w3c.org/AudioVideo.[OL]
[30] Synchronized Multimedia Working Group of W3C. Synchronized Mu].timedia Integration Language (SMIL) 2.0 Specification. http://www.w3.org/TR/smil20,[OL] August 2001.
[31] 张平，蒋凡．在网上用SMIL实现多媒体同步．计算机应用．2001年5月，第21卷(5)：55～56．
[32] 刘斌，杜欢等．基于XML的同步多媒体课件制作系统．小型微型计算机系统．2000年7月，第21卷第七期：779～781．
[33] 鄢红国，姚慧广，基于UML的远程教学系统的设计，[J]计算机与现代化，2002．8：59～60．
[34] 徐静，刘传文，用UML建模XML应用的研究及实现．[J]微型机与应用．2002
年第6期：58～60．
[35] 陈福集，杨善林；基于XML的个性化课件开发环境研究，[J]计算机工程，2003年2月，29(2)：221～230．
[36] 刘煜海，陆蕙西等．流式媒体同步集成技术在远程教学信息系统中的应用．计算机工程[J]．2001年1月．第27卷第1期．109～111．
[37] 李拥军，王惟言等．基于多agent网际实时教学系统的研究和实现．[J]计算机工程与应用．2003．18，181～183．
[38] 黄发国，应时，丰波等，用UML为XML Schema建模。[J]计算机应用，2001，21：19～21．
[39] 曹忠升，刘会志，J2EE平台构建远程教学答疑系统，[J]计算机辅助工程，2002，6(2)：43～47．
[40] 杨存东，申瑞民，张同珍．基于IMS规范的个性Web课件制作模型研究及实现，[J]小型微型计算机系统，2002，25(5)：540～543．
[41] W3C. XSL Transformations(XSLT)Version 1.0. W3C Recommendation 16 November 1999. http://www.w3. org/TR/xslt
[42] W3C. XML Path Language(Xpath) Version 1.0. W3Crecommendation 16 November 1999. http://www.w3. org/TR/xpath.
[43] W3C. XML Lingking Language(Xlink)Version 1.0. W3C Recommendation 27 June 2001. http://www.w3.org/TR/xlink/.
[44] W3C.Document Object Model(DOM)Level 2 Core Specification Version1.0. W3C Recommendation 13 November, 2000. http://www.w3.org/TR/DOM-Level-2-Core.