基于跨组织工作流的Web服务组合技术的研究
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摘要
Internet发展至今，在完成了网络的物理架构后，进入应用阶段，即充分利
用网络通信和处理能力来创造财富和价值。在Web服务出现前，分布式客户/服
务器的概念几乎仅限于HTML表单与动态数据库驱动的网站间的交互。Web服
务的出现改变了我们有关网络动态的概念，它通过使用一套标准规范提供全球范
围的服务，应使信息的生产者和消费者相互之间能够更容易地进行定位和交换信
息。然而，要通过Web服务构建复杂的应用存在一个问题：Web服务是无状态
操作(stateless operations)，所以只能提供相对较小的原子应用。但Web服务是
可以集成的，这是它的一个重要特征。因此，我们可以通过原有Web服务的组
合构成新的更复杂、功能更强大的Web服务。工作流理论作为组合Web服务的
一个重要的主要机制，对于快速创建新的、功能更强大的Web服务来说至关重
要。工作流的概念起源于生产组织和办公自动化领域，可以看成是经营过程的一
个计算机实现，是一种对工作进行优化的方法：即通过加强各个工作之间的通信
和交流，形成协同，从而达到优化。本文主要围绕工作流理论在Web服务组合
中的应用展开，将Web服务看作是工作流的组件，说明了如何构造跨组织工作
流及通过相关的Web服务组合技术(如WSFL)实现跨组织工作流，从而实现
Web服务的集成。文章以网上购书为例，贯穿全文，并在最后给出其WSFL模
型。
本文从Web服务的定义和体系结构出发，引入Web服务协议栈，并详细说
明了构成Web服务的各个标准规范及其功能，以及协议的基础--XML。接着，
对工作流理论进行了详细的介绍。Petri网作为系统模型，由于其严密的数学基
础和图形建模能力，被广泛应用在分布式软件系统等离散事件动态系统(DEDS)
的建模与分析中。本文即采用Petri网对工作流进行建模。在介绍了Petri网相关
知识后，通过Petri网给出工作流网的形式化定义，并给出简化的网上购书的工
作流网。
进一步的，在工作流网的基础上，给出了跨组织工作流的概念，并用基本Petri
网的变体：带标号的库所／变迁网，对跨组织工作流网进行建模。通过另一个例
子：承包商与分包商，说明了在构造跨组织工作流网时的难点和会出现的问题及
异常，并提出了解决方法：P2P方法，并使用P2P方法完成对网上购书的跨组织
工作流网的构造。
文章最后一部分着重于跨组织工作流与Web服务相结合的探讨。文中讨论的
描述Web服务组合的WSFL语言是一个关于如何实现使用新兴Web服务架构的
业务流程模型的规范，即不是用WSFL来定义业务流程模型，而是用它来创建
业务模型的一个XML表示法。所以我们可以通过将跨组织工作流转换到WSFL
模型，并用WSFL进行描述，来实现工作流理论在Web服务组合中的应用。相
应的，以网上购书为例，对这种转换进行具体讨论。
The Internet as we know it for today, has finished its first phase----physical infrastructuIe
and it is now time to make use of the new comrnunications and processing capacity to
produce value. Usually, the notion of distributed client/serr)er computing is almost limited
to HTMi fOrms interacting with dynandc database-driven web site. Web services are about
to change the way we think about dynndc regarding the net, introducing the means to
provide services worldwide using a set of common standards, which makes it easier for
producers and consumers of infOrmation to 1ocate each other and exchange infOrmation.
Yet this interoperability lacks one crucial aspect necessary for complex applicationst web
seri'ices are stateless operations, thus only providing fOr small, atomic applications. But
t"eb sen.ices are composab1e, 1\'hich is an important characteristic of web seri)ices
\\brkfloxv, as a primary mechanism to compose Web Sen'ice5 in a nontrivial fashion, is
critical fOr the rapid creation of new, higher-fiJnction \Veb Services
ln this thesis, we focus on the implementation of workflow theory in web services
orchestration, considering web service as a component of workflow, describing how to
develop a interorganizationa1 workflow and implement it by the technique of orchestraing
web ser\'ice by means like WSFL. We use buying a book on the bookstore site as an
example through this thesis and give its WSFL models at the last part.
At first, there u,ill be an overview of web services A more or less fOrmal definition will be
gix'en xv'hen introducing the term web service. Afterwards an overview of the related
technoIogies is supplied including the service-oriented architecture, the invo1ved and
e\'ol\)ing standards, including XMi, which could be viewed as the fOundation of these
standards Then, the idea of t'7orkflotv is introduced in detail choosing Petri nets to model
the t\'orkflot"s. t\'hich is used t',ide1y in the mode1 and ana1ysis of DEDS, e.g, distributed
softt'Jare s}'stem Furthermore, interorganizational workflow is provided using the variant
of classic Petri nets f labeled Place/Transition nets to model it The difficulties occur during
the modeling of interorganizational wodriow are exp1ained and a solution is given f the P2P
Approach. At last, a description of the combination of interorganizational workflow with
x'eb sen'ices is given. The application of workflow in web services orchestration is
in1pIemented by translating the interorganizationaI workflow to the WSFL mode1s, which
can be described by WSFL
用网络通信和处理能力来创造财富和价值。在Web服务出现前，分布式客户/服
务器的概念几乎仅限于HTML表单与动态数据库驱动的网站间的交互。Web服
务的出现改变了我们有关网络动态的概念，它通过使用一套标准规范提供全球范
围的服务，应使信息的生产者和消费者相互之间能够更容易地进行定位和交换信
息。然而，要通过Web服务构建复杂的应用存在一个问题：Web服务是无状态
操作(stateless operations)，所以只能提供相对较小的原子应用。但Web服务是
可以集成的，这是它的一个重要特征。因此，我们可以通过原有Web服务的组
合构成新的更复杂、功能更强大的Web服务。工作流理论作为组合Web服务的
一个重要的主要机制，对于快速创建新的、功能更强大的Web服务来说至关重
要。工作流的概念起源于生产组织和办公自动化领域，可以看成是经营过程的一
个计算机实现，是一种对工作进行优化的方法：即通过加强各个工作之间的通信
和交流，形成协同，从而达到优化。本文主要围绕工作流理论在Web服务组合
中的应用展开，将Web服务看作是工作流的组件，说明了如何构造跨组织工作
流及通过相关的Web服务组合技术(如WSFL)实现跨组织工作流，从而实现
Web服务的集成。文章以网上购书为例，贯穿全文，并在最后给出其WSFL模
型。
本文从Web服务的定义和体系结构出发，引入Web服务协议栈，并详细说
明了构成Web服务的各个标准规范及其功能，以及协议的基础--XML。接着，
对工作流理论进行了详细的介绍。Petri网作为系统模型，由于其严密的数学基
础和图形建模能力，被广泛应用在分布式软件系统等离散事件动态系统(DEDS)
的建模与分析中。本文即采用Petri网对工作流进行建模。在介绍了Petri网相关
知识后，通过Petri网给出工作流网的形式化定义，并给出简化的网上购书的工
作流网。
进一步的，在工作流网的基础上，给出了跨组织工作流的概念，并用基本Petri
网的变体：带标号的库所／变迁网，对跨组织工作流网进行建模。通过另一个例
子：承包商与分包商，说明了在构造跨组织工作流网时的难点和会出现的问题及
异常，并提出了解决方法：P2P方法，并使用P2P方法完成对网上购书的跨组织
工作流网的构造。
文章最后一部分着重于跨组织工作流与Web服务相结合的探讨。文中讨论的
描述Web服务组合的WSFL语言是一个关于如何实现使用新兴Web服务架构的
业务流程模型的规范，即不是用WSFL来定义业务流程模型，而是用它来创建
业务模型的一个XML表示法。所以我们可以通过将跨组织工作流转换到WSFL
模型，并用WSFL进行描述，来实现工作流理论在Web服务组合中的应用。相
应的，以网上购书为例，对这种转换进行具体讨论。
The Internet as we know it for today, has finished its first phase----physical infrastructuIe
and it is now time to make use of the new comrnunications and processing capacity to
produce value. Usually, the notion of distributed client/serr)er computing is almost limited
to HTMi fOrms interacting with dynandc database-driven web site. Web services are about
to change the way we think about dynndc regarding the net, introducing the means to
provide services worldwide using a set of common standards, which makes it easier for
producers and consumers of infOrmation to 1ocate each other and exchange infOrmation.
Yet this interoperability lacks one crucial aspect necessary for complex applicationst web
seri'ices are stateless operations, thus only providing fOr small, atomic applications. But
t"eb sen.ices are composab1e, 1\'hich is an important characteristic of web seri)ices
\\brkfloxv, as a primary mechanism to compose Web Sen'ice5 in a nontrivial fashion, is
critical fOr the rapid creation of new, higher-fiJnction \Veb Services
ln this thesis, we focus on the implementation of workflow theory in web services
orchestration, considering web service as a component of workflow, describing how to
develop a interorganizationa1 workflow and implement it by the technique of orchestraing
web ser\'ice by means like WSFL. We use buying a book on the bookstore site as an
example through this thesis and give its WSFL models at the last part.
At first, there u,ill be an overview of web services A more or less fOrmal definition will be
gix'en xv'hen introducing the term web service. Afterwards an overview of the related
technoIogies is supplied including the service-oriented architecture, the invo1ved and
e\'ol\)ing standards, including XMi, which could be viewed as the fOundation of these
standards Then, the idea of t'7orkflotv is introduced in detail choosing Petri nets to model
the t\'orkflot"s. t\'hich is used t',ide1y in the mode1 and ana1ysis of DEDS, e.g, distributed
softt'Jare s}'stem Furthermore, interorganizational workflow is provided using the variant
of classic Petri nets f labeled Place/Transition nets to model it The difficulties occur during
the modeling of interorganizational wodriow are exp1ained and a solution is given f the P2P
Approach. At last, a description of the combination of interorganizational workflow with
x'eb sen'ices is given. The application of workflow in web services orchestration is
in1pIemented by translating the interorganizationaI workflow to the WSFL mode1s, which
can be described by WSFL
引文
[1] Scott Burns , Web Services Security-An Overview , http://wwv.sans.org/rr/managed/web_services.php http://www.ithospital. com/resource/itconsultant.jsp
[2] ITHospical．com，Web服务时代的生财之道， http：//www.ithospital.com/resource/itconsultant.jsp
[3] 范玉顺，工作流管理技术基础--实现企业业务过程重组、过程管理与过程 自动化的核心技术，清华大学出版社，2001
[4] 罗海滨，范玉顺，吴澄，工作流技术综述，《软件学报》，Vol．11，No．7，2000
[5] Feller, John, IBM Web Services ToolKit, A showcase for emerging web services technologies, http://www-3． ibm.com/software/solutions/websen-ices/wstk-info.html
[6] 飞思科技产品研发中心，Java Web服务应用开发详解，电子工业出版社，2002
[7] Paul Bouche, Understanding Web Service Technology, bpt.hpi.uni-potsdam.de/bpt/dataAVebServicesSeminar.pdf (Web Services Conceptual Architecture), http://www-900． ibm.com/developerWorks/cn/webservices/ws-wsca/
[8] Heather Kreger，Web服务概念性体系结构(Web Services Conceptual Architecture)。
[9] Brittenham, Peter, IBM, Web Services Development Concepts WSDC 1． 0, 2001
[10] IBM, Web Services architecture overview, http://www-106． ibm.com/developerworks/webservices/library/w-ovr/
[11] Cerami, Ethan, Top Ten FAQs for Web Services, http://www.oreillynet.com/pub/a/webservices/2002/02/l 2/webservicefaqs.html, 2002
[12] Cerami, Ethan, Web Services-Essentials, O'Reilly&Associates, 2002
[13] IBM, Web Service Flow Language (WSFL) Specification, http://www-3． ibm.com/software/solutions/webservices/pdf/WSFL.pdf, 2001
[14] Rogotzki, Antje, Web Service Publication and Discovery, Potsdam, 2002
[15] Apache, Apache AXIS SOAP, http://xml.apache.org/axis, 2002
[16] Universal Description, Discovery and Integration (UDDI) 2． 0 http://www.uddi.org, 2001
[17] Web Services Description Language 1． 2, Sanjiva Weerawarana et al., 2002
[18] Stefan Wappler, Defining a web service's interface: The Web Service Description Language, Potsdam 2002
[19] Sebastian H. Schenk, Web Service Invocation with XML-RPC and SOAP, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSeminar.pdf
[20] Antje Rogotzki, Web Service Publication and Discovery, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSerninar.pdf
[21] World Wide Web Consortium, W3C, http://www.w3． org
[22] W M.P. van der Aalst, The Application of Petri Nets to Workflow Managemnet, http://wwwis.win.tue.nl/~wsinwa/jcsc/jesc.html
[23] Matthias Heise, Workflow Nets, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSeminar.pdf
[24] W.M.P. van der Aalst, The Application of Petri Nets to Workflow Management, Eindhoven University of Technology, The Netherlands
[25] Anne Rozinat, Workflow Patterns, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSeminar.pdf
[26] W.M.P. van der Aalst, Hofstede, A.H.M. ter, Kiepuszewski B., Barros, A.P., Workflow Patterns, http://tmitwww.tm.tue.nl/research/patterns/, 2002
[27] E. Gamma, R. Helm, R. Johnson, J. Vlissides, Design Patterns: Elements of Reusable Object-Oriented Software, Addison-Wesley, 1995
[28] Udo Werner, Interorganisational Workflows, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSeminar.pdf
[29] W.M.P. van der Aalst, M. Weske, The P2P Approach to Interorganizational Workflows, www.darmstadt.gmd.de/~wombach/sem_proc_02/ the-p-p-approach.pdf
[30] WM.P. van der Aalst, Inheritance of Interorganizational Workflows: How to Agree to Disagree Without Loosing Control? wwwis.win.tue.nl/~debra/2R480/tods_aalst.pdf
[31] W.M.P. van der Aalst, Verification of Workflow Nets, In P. Az'ema and G. Balbo, editors, Application and Theory of Petri Nets 1997, volume 1248 of Lecture Notes in Computer Science, pages 407-426． Springer-Verlag, Berlin, 1997．
[32] W.M.P. van der Aalst, Finding Errors in the Design of aWorkflow Process: A Petri-net-based Approach. In W.M.P. van der Aalst, G. De Michelis, and C.A. Ellis, editors, Proceedings of Workflow Management: Net-based Concepts, Models, Techniques and Tools (WFM'98) , volume98/7 of Computing Science Reports, Lisbon, Portugal, 1998 Eindhoven. University of Technology, Eindhoven.
[33] W.M.P. van der Aalst, The Application of Petri Nets toWorkflow Management The Journal of Circuits, Systems and Computers, 8(1) :21-66, 1998．
[34] W.M.P. van der Aalst and T. Basten, Inheritance of Workflows: An approach to tackling problems related to change. Computing Science Reports 99/06, Eindhoven University of Technology, Eindhoven, 1999
[35] N.R.Adam, V. Atluri, W.Huang, Modeling and Analysis of Workflows using Petri Nets, Journal of Intelligent Information Systems, 10(2) : 13 1-158, 1998．
[36] A. Kumar, J.L. Zhao, Workflow Support for Electronic Commerce Applications, http ://spot. Colorado. edu/akhil/, 1999
[37] Chistian W. Gunther, Implementing Interorganizational Workflows via Web Services Orchestration, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSeminar.pdf
[38] Frank Keller, Peter Tabeling, Remy Apfelbacher, Bernhard Grone, Andreas Knopfel, Rudolf Kugel, Oliver Schmidt, Improving Knowledge Transfer at the Architectural Level: Concepts and Notations, http://www.hpi.unipotsdam.de/source/fachgebiete/modellierung/keller_et_al_2002-im proving_knowtrans_on_archlevel.pdf
[39] Frank Leymann, Web Services Flow Language (WSFL 1． 0) Draft Standard Publication of the IBM Software Group, http://www.ibm.com/software/solutions/webservices/pdf/WSFL.pdf
[40] C. W. Giinther,fLowRider-Prototypical Implementation of a WSFL flow engine for demonstration and research purposes, http://flowrider.sourceforge.net/
[41] James Snell，Web服务内幕， http：//www-900． ibm．com/developerWorks/cn/webservices/ws-ref/
[42] Stuart J.Johnston,协调Web Services， www.ftponline.com/china/Articles.aspx?ID=34&OON=Old
[2] ITHospical．com，Web服务时代的生财之道， http：//www.ithospital.com/resource/itconsultant.jsp
[3] 范玉顺，工作流管理技术基础--实现企业业务过程重组、过程管理与过程 自动化的核心技术，清华大学出版社，2001
[4] 罗海滨，范玉顺，吴澄，工作流技术综述，《软件学报》，Vol．11，No．7，2000
[5] Feller, John, IBM Web Services ToolKit, A showcase for emerging web services technologies, http://www-3． ibm.com/software/solutions/websen-ices/wstk-info.html
[6] 飞思科技产品研发中心，Java Web服务应用开发详解，电子工业出版社，2002
[7] Paul Bouche, Understanding Web Service Technology, bpt.hpi.uni-potsdam.de/bpt/dataAVebServicesSeminar.pdf (Web Services Conceptual Architecture), http://www-900． ibm.com/developerWorks/cn/webservices/ws-wsca/
[8] Heather Kreger，Web服务概念性体系结构(Web Services Conceptual Architecture)。
[9] Brittenham, Peter, IBM, Web Services Development Concepts WSDC 1． 0, 2001
[10] IBM, Web Services architecture overview, http://www-106． ibm.com/developerworks/webservices/library/w-ovr/
[11] Cerami, Ethan, Top Ten FAQs for Web Services, http://www.oreillynet.com/pub/a/webservices/2002/02/l 2/webservicefaqs.html, 2002
[12] Cerami, Ethan, Web Services-Essentials, O'Reilly&Associates, 2002
[13] IBM, Web Service Flow Language (WSFL) Specification, http://www-3． ibm.com/software/solutions/webservices/pdf/WSFL.pdf, 2001
[14] Rogotzki, Antje, Web Service Publication and Discovery, Potsdam, 2002
[15] Apache, Apache AXIS SOAP, http://xml.apache.org/axis, 2002
[16] Universal Description, Discovery and Integration (UDDI) 2． 0 http://www.uddi.org, 2001
[17] Web Services Description Language 1． 2, Sanjiva Weerawarana et al., 2002
[18] Stefan Wappler, Defining a web service's interface: The Web Service Description Language, Potsdam 2002
[19] Sebastian H. Schenk, Web Service Invocation with XML-RPC and SOAP, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSeminar.pdf
[20] Antje Rogotzki, Web Service Publication and Discovery, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSerninar.pdf
[21] World Wide Web Consortium, W3C, http://www.w3． org
[22] W M.P. van der Aalst, The Application of Petri Nets to Workflow Managemnet, http://wwwis.win.tue.nl/~wsinwa/jcsc/jesc.html
[23] Matthias Heise, Workflow Nets, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSeminar.pdf
[24] W.M.P. van der Aalst, The Application of Petri Nets to Workflow Management, Eindhoven University of Technology, The Netherlands
[25] Anne Rozinat, Workflow Patterns, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSeminar.pdf
[26] W.M.P. van der Aalst, Hofstede, A.H.M. ter, Kiepuszewski B., Barros, A.P., Workflow Patterns, http://tmitwww.tm.tue.nl/research/patterns/, 2002
[27] E. Gamma, R. Helm, R. Johnson, J. Vlissides, Design Patterns: Elements of Reusable Object-Oriented Software, Addison-Wesley, 1995
[28] Udo Werner, Interorganisational Workflows, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSeminar.pdf
[29] W.M.P. van der Aalst, M. Weske, The P2P Approach to Interorganizational Workflows, www.darmstadt.gmd.de/~wombach/sem_proc_02/ the-p-p-approach.pdf
[30] WM.P. van der Aalst, Inheritance of Interorganizational Workflows: How to Agree to Disagree Without Loosing Control? wwwis.win.tue.nl/~debra/2R480/tods_aalst.pdf
[31] W.M.P. van der Aalst, Verification of Workflow Nets, In P. Az'ema and G. Balbo, editors, Application and Theory of Petri Nets 1997, volume 1248 of Lecture Notes in Computer Science, pages 407-426． Springer-Verlag, Berlin, 1997．
[32] W.M.P. van der Aalst, Finding Errors in the Design of aWorkflow Process: A Petri-net-based Approach. In W.M.P. van der Aalst, G. De Michelis, and C.A. Ellis, editors, Proceedings of Workflow Management: Net-based Concepts, Models, Techniques and Tools (WFM'98) , volume98/7 of Computing Science Reports, Lisbon, Portugal, 1998 Eindhoven. University of Technology, Eindhoven.
[33] W.M.P. van der Aalst, The Application of Petri Nets toWorkflow Management The Journal of Circuits, Systems and Computers, 8(1) :21-66, 1998．
[34] W.M.P. van der Aalst and T. Basten, Inheritance of Workflows: An approach to tackling problems related to change. Computing Science Reports 99/06, Eindhoven University of Technology, Eindhoven, 1999
[35] N.R.Adam, V. Atluri, W.Huang, Modeling and Analysis of Workflows using Petri Nets, Journal of Intelligent Information Systems, 10(2) : 13 1-158, 1998．
[36] A. Kumar, J.L. Zhao, Workflow Support for Electronic Commerce Applications, http ://spot. Colorado. edu/akhil/, 1999
[37] Chistian W. Gunther, Implementing Interorganizational Workflows via Web Services Orchestration, bpt.hpi.uni-potsdam.de/bpt/data/WebServicesSeminar.pdf
[38] Frank Keller, Peter Tabeling, Remy Apfelbacher, Bernhard Grone, Andreas Knopfel, Rudolf Kugel, Oliver Schmidt, Improving Knowledge Transfer at the Architectural Level: Concepts and Notations, http://www.hpi.unipotsdam.de/source/fachgebiete/modellierung/keller_et_al_2002-im proving_knowtrans_on_archlevel.pdf
[39] Frank Leymann, Web Services Flow Language (WSFL 1． 0) Draft Standard Publication of the IBM Software Group, http://www.ibm.com/software/solutions/webservices/pdf/WSFL.pdf
[40] C. W. Giinther,fLowRider-Prototypical Implementation of a WSFL flow engine for demonstration and research purposes, http://flowrider.sourceforge.net/
[41] James Snell，Web服务内幕， http：//www-900． ibm．com/developerWorks/cn/webservices/ws-ref/
[42] Stuart J.Johnston,协调Web Services， www.ftponline.com/china/Articles.aspx?ID=34&OON=Old