P2P网络Peer访问WebService的研究和实现
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摘要
P2P是人们针对C／S结构提出的一种网络结构，这种网络结构中所有的网络结点是互相对等的，它们既是Client又是Server。P2P通过这些对等体之间的直接交换实现计算资源和服务的共享。WebService是人们针对开发分布式应用程序的又一新技术。它是建立可互操作的分布式应用程序的新平台，同时它也为应用程序通信提供了一种独立于平台、组建模型和编程语言的标准。
P2P和WebService两种技术都有着非常广阔的应用前景，也必然存在相互之间的互操作应用，特别是由于大量的WebService资源已经存在，P2P网络中Peer必然需要对这些WebService进行访问和调用，使用Web服务的P2P应用程序也会更加标准、更易于访问、更易于理解并更容易集成。本课题就此提出将WebService这个概念融入P2P网络，使得P2P网络Peer可以访问现有的WebService资源，解决现有P2P应用程序中的许多常见问题。
本文实现P2P与WebService的集成主要着眼点在于：
· 透明性。P2P网络中Peer发现WebService的过程对其是透明的，就像Peer发现P2P网络内部提供的服务一样，以及Peer可以透明的调用和访问WebService，就象Peer访问P2P网络内部的服务一样。
· 易于扩展。实现希望在WebService的协议出现变化时，所需的修改工作是针对P2P网络中部分Peer，而不是全体。
为此本文提出了WebServiceBroker的概念，WebServiceBroker是Peer访问WebService的代理，实际上也是一个Peer或者一个Peer组，向P2P网络中所有Peer提供接受并处理WebService请求的服务，然后负责发现和调用WebService的任务。继而，本文给出了Peer利用WebServiceBroker完成WebService访问的框架和基本实现方法。基本框架可阐述为：Peer利用JXTA发现机制发现WebServiceBroker，接着向其发出WebService查询请求，然后由WebServiceBroker进行WebService服务注册中心的查询，并将结果返回给Peer，Peer利用返回结果调用WebServiceBroker服务(WebServiceBroker向所有Peer提供的服务被视为普通的JXTA服务，文章称其为WebServiceBroker服务)，最后由WebServiceBroker完成真正的WebService服务调用。
最后本文自行编写并发布了一个WebService，进行对基本实现方法的验证，测试证明Peer能够通过WebServiceBroker访问到已开发并发布的WebService。
P2P is a kind of network architecture against Client/Server architecture.In this architecture,all of the network nodes are Peer to Peer,they are both clients and servers.P2P implements the sharing of computing resources and services through the direct communication of the peers. WebService is a new technology used to develope distrubuted application.lt is a new platform to build distrubuted application which are interoperable.In the meantime,it provides a standard which is independent on platfonru building model and program language for the communication between the applications.
P2P and WebService will be applied widely in the future.It is certain that there are interoperable applications between the two technologies.Especially a number of WebService resources have existed,the P2P network peers need to access and invoke these WebServices inevitably. Also P2P applictions using Web Services will be more standard,easier to access, understand and integrate.Thus the thesis puts forward the idea of integrating the WebService concept into P2P network, make the peers can access existing WebService resources and solve most of the current common problems in the P2P applications.
The implementation of integrating the WebService into P2P in the thesis places emphases on:
Transparency. The procedure of finding the WebService is transparent to the peer,as if it finds the inner services in the P2P network.The peer can invoke and access the Web Service transparently,as if it accesses the inner services in the P2P network.
Extensibility. The implementation hopes that when the WebService protocols change,only a part of peers not all peers need modifications.
For these purposes,the thesis brings forward the concept of WebServiceBroker.It is a broker used for the peers to access WebService.In fact it is a peer or a peer group to provide the service of accepting and dealing with the WebService query,and fulfill the task of searching and invoking the WebService.Following that,the thesis provides a framework and elementary implementations of how the peers access WebService through WebServiceBroker.The framework is that the peer makes use of the JXTA searching mechanism to find a WebServiceBroker,then sends a WebService query to it,the WebServiceBroker receives it and queries the WebService Service Registry,then returns the query result to the peer,the peer uses the result to invoke the WebServiceBroker Service(the thesis looks on the service provided by the WebServiceBroker to all peers as a JXTA service,calls it WebServiceBroker service),at last the WebServiceBroker accomplishes the true WebService invoking.
Finally the thesis writes and publishes a simple WebService used to test the implementaion.The result of the testing proves that the peer can access and invoke the Web Service developed and published by the thesis through the WebServiceBroker.
P2P和WebService两种技术都有着非常广阔的应用前景，也必然存在相互之间的互操作应用，特别是由于大量的WebService资源已经存在，P2P网络中Peer必然需要对这些WebService进行访问和调用，使用Web服务的P2P应用程序也会更加标准、更易于访问、更易于理解并更容易集成。本课题就此提出将WebService这个概念融入P2P网络，使得P2P网络Peer可以访问现有的WebService资源，解决现有P2P应用程序中的许多常见问题。
本文实现P2P与WebService的集成主要着眼点在于：
· 透明性。P2P网络中Peer发现WebService的过程对其是透明的，就像Peer发现P2P网络内部提供的服务一样，以及Peer可以透明的调用和访问WebService，就象Peer访问P2P网络内部的服务一样。
· 易于扩展。实现希望在WebService的协议出现变化时，所需的修改工作是针对P2P网络中部分Peer，而不是全体。
为此本文提出了WebServiceBroker的概念，WebServiceBroker是Peer访问WebService的代理，实际上也是一个Peer或者一个Peer组，向P2P网络中所有Peer提供接受并处理WebService请求的服务，然后负责发现和调用WebService的任务。继而，本文给出了Peer利用WebServiceBroker完成WebService访问的框架和基本实现方法。基本框架可阐述为：Peer利用JXTA发现机制发现WebServiceBroker，接着向其发出WebService查询请求，然后由WebServiceBroker进行WebService服务注册中心的查询，并将结果返回给Peer，Peer利用返回结果调用WebServiceBroker服务(WebServiceBroker向所有Peer提供的服务被视为普通的JXTA服务，文章称其为WebServiceBroker服务)，最后由WebServiceBroker完成真正的WebService服务调用。
最后本文自行编写并发布了一个WebService，进行对基本实现方法的验证，测试证明Peer能够通过WebServiceBroker访问到已开发并发布的WebService。
P2P is a kind of network architecture against Client/Server architecture.In this architecture,all of the network nodes are Peer to Peer,they are both clients and servers.P2P implements the sharing of computing resources and services through the direct communication of the peers. WebService is a new technology used to develope distrubuted application.lt is a new platform to build distrubuted application which are interoperable.In the meantime,it provides a standard which is independent on platfonru building model and program language for the communication between the applications.
P2P and WebService will be applied widely in the future.It is certain that there are interoperable applications between the two technologies.Especially a number of WebService resources have existed,the P2P network peers need to access and invoke these WebServices inevitably. Also P2P applictions using Web Services will be more standard,easier to access, understand and integrate.Thus the thesis puts forward the idea of integrating the WebService concept into P2P network, make the peers can access existing WebService resources and solve most of the current common problems in the P2P applications.
The implementation of integrating the WebService into P2P in the thesis places emphases on:
Transparency. The procedure of finding the WebService is transparent to the peer,as if it finds the inner services in the P2P network.The peer can invoke and access the Web Service transparently,as if it accesses the inner services in the P2P network.
Extensibility. The implementation hopes that when the WebService protocols change,only a part of peers not all peers need modifications.
For these purposes,the thesis brings forward the concept of WebServiceBroker.It is a broker used for the peers to access WebService.In fact it is a peer or a peer group to provide the service of accepting and dealing with the WebService query,and fulfill the task of searching and invoking the WebService.Following that,the thesis provides a framework and elementary implementations of how the peers access WebService through WebServiceBroker.The framework is that the peer makes use of the JXTA searching mechanism to find a WebServiceBroker,then sends a WebService query to it,the WebServiceBroker receives it and queries the WebService Service Registry,then returns the query result to the peer,the peer uses the result to invoke the WebServiceBroker Service(the thesis looks on the service provided by the WebServiceBroker to all peers as a JXTA service,calls it WebServiceBroker service),at last the WebServiceBroker accomplishes the true WebService invoking.
Finally the thesis writes and publishes a simple WebService used to test the implementaion.The result of the testing proves that the peer can access and invoke the Web Service developed and published by the thesis through the WebServiceBroker.
引文
[1]. 2001 P2P Networking Overview" Clay Shirky ,Kelly Truelov , Rael Dornfest & Lucas Gonze
[2]. " Project JXIA:An Open, Innovative Collaboration "Sun Microsystems
[3]. " Project JXTA : Getting Started " Sun Microsystems
[4]. " Project JXTA:A Technology Overview " Li Gong, Sun Microsystems
[5]. " JXTA V1.0 Protocols Specification " Sun Microsystems
[6]. " Project JXTA : Java Programmer' s Guide " Sun Microsystems
" JXTA Search : Distributed Search for Distributed Networks " Steve Waterhouse, Sun Microsystems
[7]. " Project JXTA: Technical Shell Overview " Sun Microsystems
[8]. "Web Service Architecture" Michael Champion, Chris Ferris, Eric Newcomer, David Orchard
[9]. "Simple Object Access Protocol(SOAP)1.1" Don Box, David Ehnebuske, Gopal Kakivaya, Andrew Layman, Noah Mendelsohn, Satish Thatte
[10]. "Web Services Description Language (WSDL) 1.1" Erik Christensen, Francisco Curbera, Greg Meredith, Sanjiva Weerawarana
[11]. "Universal Description Discovery & Integration(UDDI) Version 3.0 " Tom Bellwood, Luc Clement etc, UDDI Spec Technical Committee
[12]. " XML Schema Structures " Henry S Thompson, David Beech, Murray Maloney and Noah Mendelsohn [http://www.w3c.org/TR/xmlschema-1/]W3C 2 May 2001
[13]. " XML Schema Part 2: Datatypes" Paul V. Biron and Ashok Malhotra [http://www.w3c. org/TR/xmlschema-2/] W3C 2 May 2001
[14]．“Java 2核心技术 卷一：基础知识” Cay S．Horstmann，Gary Comell著 京京工作室译 机械工业出版社
[15]．“Java 2核心技术 卷二：高级特性” Cay S．Horstmann，Gary Comell著 朱志，王怀，赵伟译 机械工业出版社
[16]．“Soap：XML跨平台WebService开发技术” Scott Seely，杨涛 杨晓云等译 北京：机械工业出版社，2002．4
[17]. http://www.jxta.org/-home Web Page for Project JXTA
[18]. http://spec, jxta. org-Project JXTA specification
[19]. http://platform, jxta. org-Project JXTA platform infrastructure
[20]. http://www.zdnet, com. cn/developer/tech/story/0,2000081602,391562 56,00.htm-P2P网络中使用Web服务的好处
[21]. http://www.w3c.org/-The World Wide Web Consortium
[22]. http://www.w3.org/TR/SOAP/
[23]. http://www-900.ibm.com/developerWorks/cn/xml/theme/indexcxl.shtm 1-Web Service Case Study系列
[24]. http://www.uddi.org/-home Web page for Project UDDI
[25]. http://www.uddi4j.org-home Webpage for Project UDDI4J
[26]. http://www-900.ibm.com/developerWorks/cn/webservices/ws-uddi4j2/index,shtml-UDDI4J编程
[27]. http://ws.apache.org/soap/index.html-WebServices-SOAPIntroduction
[2]. " Project JXIA:An Open, Innovative Collaboration "Sun Microsystems
[3]. " Project JXTA : Getting Started " Sun Microsystems
[4]. " Project JXTA:A Technology Overview " Li Gong, Sun Microsystems
[5]. " JXTA V1.0 Protocols Specification " Sun Microsystems
[6]. " Project JXTA : Java Programmer' s Guide " Sun Microsystems
" JXTA Search : Distributed Search for Distributed Networks " Steve Waterhouse, Sun Microsystems
[7]. " Project JXTA: Technical Shell Overview " Sun Microsystems
[8]. "Web Service Architecture" Michael Champion, Chris Ferris, Eric Newcomer, David Orchard
[9]. "Simple Object Access Protocol(SOAP)1.1" Don Box, David Ehnebuske, Gopal Kakivaya, Andrew Layman, Noah Mendelsohn, Satish Thatte
[10]. "Web Services Description Language (WSDL) 1.1" Erik Christensen, Francisco Curbera, Greg Meredith, Sanjiva Weerawarana
[11]. "Universal Description Discovery & Integration(UDDI) Version 3.0 " Tom Bellwood, Luc Clement etc, UDDI Spec Technical Committee
[12]. " XML Schema Structures " Henry S Thompson, David Beech, Murray Maloney and Noah Mendelsohn [http://www.w3c.org/TR/xmlschema-1/]W3C 2 May 2001
[13]. " XML Schema Part 2: Datatypes" Paul V. Biron and Ashok Malhotra [http://www.w3c. org/TR/xmlschema-2/] W3C 2 May 2001
[14]．“Java 2核心技术 卷一：基础知识” Cay S．Horstmann，Gary Comell著 京京工作室译 机械工业出版社
[15]．“Java 2核心技术 卷二：高级特性” Cay S．Horstmann，Gary Comell著 朱志，王怀，赵伟译 机械工业出版社
[16]．“Soap：XML跨平台WebService开发技术” Scott Seely，杨涛 杨晓云等译 北京：机械工业出版社，2002．4
[17]. http://www.jxta.org/-home Web Page for Project JXTA
[18]. http://spec, jxta. org-Project JXTA specification
[19]. http://platform, jxta. org-Project JXTA platform infrastructure
[20]. http://www.zdnet, com. cn/developer/tech/story/0,2000081602,391562 56,00.htm-P2P网络中使用Web服务的好处
[21]. http://www.w3c.org/-The World Wide Web Consortium
[22]. http://www.w3.org/TR/SOAP/
[23]. http://www-900.ibm.com/developerWorks/cn/xml/theme/indexcxl.shtm 1-Web Service Case Study系列
[24]. http://www.uddi.org/-home Web page for Project UDDI
[25]. http://www.uddi4j.org-home Webpage for Project UDDI4J
[26]. http://www-900.ibm.com/developerWorks/cn/webservices/ws-uddi4j2/index,shtml-UDDI4J编程
[27]. http://ws.apache.org/soap/index.html-WebServices-SOAPIntroduction