毕业论文（设计）基于OWLS 的地理信息服务语义描述研究38406.doc

基于OWL-S的地理信息服务语义描述研究李宏伟 李勤超 蔡畅（信息工程大学测绘学院，郑州，450052）摘要：OWL-S是一种用来描述Web服务属性和功能的OWL本体规范。本文在讨论OWL-S内涵的基础上，以土地利用变更作为研究实例，剖析了土地利用变更服务涉及的本体概念、所需原子服务、输入/输出、前置条件和土地利用变更任务组合过程，并用OWL-S对土地利用变更服务进行了语义描述，对于探索基于OWL-S的地理信息语义服务、实现地理信息服务共享有重要示范作用。 通常，我们习惯于用WSDL描述Web服务，但是WSDL在表达Web服务的语义信息方面存在明显不足,这对服务信息共享、服务执行自动化是一个技术上的障碍。那么能否换一种描述方法呢？OWL-S给我们提供了新思路。2 1 关于OWL-S OWL-S是一种用来描述Web服务属性和功能的OWL本体规范，它使用一系列基本的类和属性来描述服务，提供了一个可共享的框架。它的目标是使得Web服务成为计算机可理解的实体，从而实现服务的自动发现、选择、调用、互操作、组合、执行监控等任务。OWL-S提供高层Ontology用于描述Web服务，该Ontology 可以扩展用于特定领域，通过Ontology来实现对Web服务的机器可理解的描述。 OWL-S的前身是DAML-S，自2001年5月来经历多次版本升级，有10余个研究机构参与了OWL-S的开发。OWL-S定义了一组核心语言构件，用于对Web服务进行逻辑化描述，所生成的描述文件支持机器理解，从而支持代理程序基于逻辑语义实现对Web服务的自动发现、调用、组合及监控。作为描述Web服务的知识本体，OWL-S的目标是能够对一个Web服务进行逻辑描述，包括如下几个方面：（1）、Web服务做什么，例如服务实体、服务可以实现的功能、以及服务的性能参数等，可以通过“ServiceProfile”来描述和实现。基于此，服务请求实体(人或代理程序)可以发现满足特定功能需要的Web服务，确定需要满足哪些条件才能调用该服务。同时，服务请求代理也可以遵循“ServiceProfile”来描述自己的服务需求。（2）、Web服务如何执行，包括服务执行的先后顺序、过程流程等，可以通过“ServiceModel”来描述和实现。服务请求代理利用“ServiceModel”可组合多个服务以完成复杂任务，同时在服务执行过程中，可以利用“ServiceModel”来协调参与各方的动作。（3）、Web服务如何调用，例如服务地址、通信协议及消息格式等具体的绑定信息。可以通过“ServiceGrounding”来描述和1实现。（4）、Web服务如何组装。给出高层的目标描述后，对于某个任务而言，对所需要的服务进行自动选择、组装和互操作。通过OWL-S，用于选择和组合服务的信息将在Web站点被编码。OWL-S必须提供选择单个服务的先决条件和组合顺序。 OWL-S存在如下约定:一个Web服务最多有一个“ServiceModel”；一个“ServiceGrounding”必须且仅能与一个Web服务对应；一个Web服务可以没有“ServiceProfile”和“ServiceModel”；一个Web服务可以有多个“ServiceProfile”和多个“ServiceGrounding”。 下面通过一个土地利用变更服务实例来说明OWL-S的具体应用。3 2、土地利用变更服务实例问题域分析 在土地利用领域，土地利用权属单位会经常发生变更，这也是土地管控部门最关注的问题。土地利用权属变更的基本过程可以概括为：获得和记录初始土地利用编码（LanduseID）、类型（LanduseType）、位置（LanduseLocation）、面积（LanduseArea）、权属单位（PropertyUnit）和变更后土地利用编码、类型、名称、位置、面积、权属单位，根据变化生成新的土地利用权属图层。我们尝试对土地利用权属变更的过程进行分解，给出其OWL-S描述。 首先，定义土地利用变更服务涉及的本体概念（图1）。主要包括变更前后的土地利用图层（图层名称和文件）、特征（编码、类型、位置、面积、权属）、几何类型（“图斑”-LanduseParcel）。 接着，定义土地利用变更服务所需的原子服务，主要涉及到的服务如表1所示。 下一步，为每个原子服务设置输入、输出、前置条件和效果等。如将变更前和变更后的土地利用坐标值作为输入值，通过简单的运算输出土地利用变更面积。 最后，对每个基本过程进行合成，形成一个复合过程。土地利用变更服务可以分解为4个任务，即土地利用变更数据服务、土地利用变更特征服务、土地利用变更信息显示和变更结果的保存，每个任务完成相应的功能（表1）。图1土地利用变更服务设计的本体概念组成图表1 土地利用变更基本服务过程服务序号服务类型任  务功  能1土地利用变更数据服务GetLanduseCoordinate获取土地利用覆盖坐标2土地利用变更特征服务（时间维）RecordLanduseChangeLanduseID土地利用图斑唯一标识码3LanduseType土地利用类型5LanduseArea土地利用图斑面积6PropertyUnit土地利用权属7表现服务DispalyLanduseChangeLayer显示土地利用变化图层8注册服务WriteLanduseChangeFile生成和保存土地利用变化文件各个基本过程具有一定的协同关系。基本逻辑流程是：根据获取变更前土地利用信息获取变更后的土地利用信息通过简单运算获得变化信息显示变化图层信息存档变更的结果。该过程的控制流程见图2。图2 土地利用变更服务的控制流程3、基于OWL-S的土地利用变更服务语义描述3.1、Services定义首先对土地利用变更服务进行定义。通过属性“presents”指向ServiceProfile文件，通过属性“describedBy”指向ProcessModel文件，通过属性“supports”指向Grounding文件。<service:service rdf:about="http:/ LanduseChange/Task_LanduseGeometricPaecelService.owl#ServiceTask_ LandusAreaChange "><service:presentsrdf:resource="http:/ LanduseChange/Task_LanduseProfile.owl#ProfileTask_ LandusAreaeChange"/><service:describedByrdf:resource="http:/ LanduseChange/Task_LanduseProfileProcess.owl#ProcessTask_ LanduseAreaChange "/><service:supportsrdf:resource="http:/ LanduseChange/Task_LanduseGrounding.owl#GroundingTask_ LanduseAreaChange "/></service:service>3.2、Services Profile定义描述服务名称、服务所属类别、功能描述信息（包括输入、输出、前提条件、预期结果等）。ServiceProfile第一组属性描述Web服务提供实体，用“serviceName”属性给出与链接的Web服务的标识名,用“textDescription”属性给出简单的服务描述(如:服务能提供的内容,服务的工作环境等),用“contactInformation”属性给出服务提供商希望共享信息的对象。ServiceProfile第二组属性描述服务功能，采用IOPE(Input, Output, Precondition, Effect)方法，从两个互补的角度同时揭示Web服务功能。其中一个是信息流角度，通过输入信息I和输出信息O表示；另一个是状态流角度，通过服务执行前的判断条件P和结果表示E。因此，服务功能属性包括服务的输入信息(hasInput)、输出信息(hasOutput)、执行服务的前提条件(hasPrecondition)和服务执行的预期结果(hasEffect)。ServiceProfile第三组属性提供了一种机制来描述各种服务的特性，如“serviceCategory”是对Web服务的分类说明。<profile:profile rdf:about="LanduseChange.owl#ProfileTask_ LanduseChange"><profile:serviceName>="Task_LanduseAreaChange"<profile:presentsBy rdf:resource="LanduseChangeService.owl#ServiceTask_LanduseAreaChange"/><profile:serviceCategory rdf:type="http:/www.daml.org/services/owl-s/1.0/Profile.owl#ServiceCategory"/><profile:hasInput rdf:resource="LanduseChangeProcess.owl# LanduseGeometricType_1_Task_ LanduseAreaChange_Input"/> < profile:hasInput rdf:resource="LanduseChangeProcess.owl# LanduseGeometricType_2_Task_ LanduseAreaChange_Input"/> <profile:hasInput rdf:resource="LanduseChangeProcess.owl# LanduseChangeFileName _1_Task_LanduseAreaChange_Input"/><profile:hasInput rdf:resource="LanduseChangeProcess.owl# LanduseChangeFileName_1_Task_WriteLanduseAreaChangeFile_output"/></profile:profile>3.3、Process Models文件包括原子服务和服务过程的描述。原子过程中不包含子过程，从服务请求方的角度看，原子过程的过程执行是一步实现的，即按照输入-运行-输出的模式，它的内部执行过程是透明的。一个原子过程需要一个相应的部署(Grounding)文件，提供原子过程的调用地址及输入消息的构建。简单过程可看作原子过程或复合过程的抽象视图，它能够根据不同的粒度要求对原子过程或复合过程进行抽象，应用于过程计划和推理。可以将简单过程的过程执行想象成一步式的，类似于原子过程，但实际上简单过程是不可调用的，也没有具体的部署文件。当通过简单过程提供原子过程视图时，相应的原子过程实现了(realizes)简单过程；当通过简单过程提供简化的复合过程视图时，简单过程可以扩展成(expandsTo)复合过程。一个复合过程可被分解成多个子过程，这些子过程可以是复合过程，也可以是非复合过程。复合过程的分解依赖于过程中使用的控制构件(control construct)，如Sequence, If-Then-Else等，过程分解明示了复合过程的各个子过程如何接受输入信息，以及如何返回输出信息。<process:CompositeProcess rdf:ID=" ProcessTask_LanduseAreaChange"><process:composedOf><process:Sequence><process:components rdf:parseType="Collection"><process:AtomicProcess rdf:about="# GetLanduseCoordinate"/><process:AtomicProcess rdf:about="#LanduseAreaChange"/><process:CompositeProcess rdf:about="#DisplayLanduseChangeLayer"/></process:components></process:Sequence></process:composedOf></process:CompositeProcess> <process:AtomicProcess rdf:ID=" LanduseCoordinate"><process:hasInput rdf:resource="#LanduseAreaChangeName_In"/> <process:hasOutput rdf:resource="# LanduseCoordinate"_Out"/></process:AtomicProcess>待添加的隐藏文字内容33.4、ServiceGrounding文件原子服务通过Grounding文件实现与WSDL文件的连接，同时完成对原子服务的绑定信息描述。在OWL-S中，ServiceProfile和ServiceModel都可看作是服务的抽象表示，前者实现对Web服务的功能描述，后者描述服务的执行过程；但是两者都未涉及到Web服务的绑定信息，即请求方调用一个Web服务的详细信息，这部分信息在ServiceGrounding中提供。ServiceGrounding描述了如何调用一个Web服务，包括传输协议、消息格式及网络寻址等。它按照一定的消息格式，将原子过程中输入输出信息的抽象描述封装成网络可传输的消息。<grounding:WsdlGrounding  rdf:ID="GroundingTask_LanduseChangeArea"><service:supportedBy rdf:resource="LanduseChangeArea.owl#ServiceTask_LanduseChangeArea "/> <grounding:hasAtomicProcessGrounding rdf:resource="#WsdlGrounding_LanduseCoordinate"/><grounding:hasAtomicProcessGrounding rdf:resource="#WsdlGrounding_LanduseChangeArea"/><grounding:hasAtomicProcessGrounding rdf:resource="#WsdlGrounding_Display LanduseChangLayer"/></grounding:WsdlGrounding>4、结论论文对土地利用变更服务过程进行了全面分析，包括定义土地利用变更服务涉及的本体概念、所需要的原子服务，为每个过程设置输入、输出和前置条件等，利用OWL-S对土地利用变更数据服务、特征服务、表现服务、注册服务进行了详细的描述和表达，总结了土地利用变更服务的控制流程。可以发现，利用OWL-S可以很好地表达特定领域的知识，能够清晰地描述服务名称、服务所属类别和功能、地理信息服务的原子过程、简单过程和组合过程，奠定了地理信息服务共享、服务执行自动化的基础。参考文献：1 岳昆等.Web服务核心支撑技术研究综述软件学报.2004, 15(3):434-435.2 The OWL Services Coalition. OWL-S: Semantic Services. http:/www. daml. org/services/owl-s/1.0/owl-s.html. (Accessed Jul. 14, 2004).3 OWL Web Ontology Language Semantics and Abstract Syntax. W3C Recommendation of February 2004. http : /www. w3.org/TR/ow-labsyn/ (Accessed Jut. 14, 2004)4 OWL-S 1.0 Release. November 2003. http:/www.daml.org/services/owl-s/1.0/ (Accessed Jul.14, 2004).5 OWL-S ServiceProfile Ontology. http:/www.daml.org/services/Owl-s/1.0 DL/Profile.owl (Accessed Jul. 16, 2004).6 OWL-S ProcessModel Ontology. http:/www. daml.org/services/owl-s/l.0 DL/Process.owl (Accessed Jul. 16, 2004).7 OWL-S ServiceGrounding Ontology. http:/www.daml.org/services/owl-s/l.0 DL/Grounding.owl (Accessed Jul. 16, 2004).8周中成等.基于语义的Web服务自动发现、匹配及执行平台计算机应用.2005, 25(1):233-235.Research on Geographic Information Service Description based on OWL-SLi hongwei   Liqinchao   Caichang(Institute of Surveying and Mapping, Information and Engineering University, Zhengzhou 450052, China)Abstract: OWL-S is OWL Ontology Specification used to describe attributes and functions of Web service. This paper discussed the basic meanings of OWL-S, took example for land-use change, analyzed Ontology that land-use change service related to, atomic service, input/output, precondition and composite process of land-use change task, described semantic of land-use change service by OWL-S. This work is very important role for Geographic Information Service share. 作者简介：李宏伟（1963），男，山东人，教授，工学博士，主要从事GIS理论与应用研究。地址：郑州市陇海中路66号测绘学院0700信箱，邮编：450052。更多测绘论文请登录测绘网论文频道查询：http:/ Editor's note: Judson Jones is a meteorologist, journalist and photographer. He has freelanced with CNN for four years, covering severe weather from tornadoes to typhoons. Follow him on Twitter: jnjonesjr (CNN) - I will always wonder what it was like to huddle around a shortwave radio and through the crackling static from space hear the faint beeps of the world's first satellite - Sputnik. I also missed watching Neil Armstrong step foot on the moon and the first space shuttle take off for the stars. Those events were way before my time.As a kid, I was fascinated with what goes on in the sky, and when NASA pulled the plug on the shuttle program I was heartbroken. Yet the privatized space race has renewed my childhood dreams to reach for the stars.As a meteorologist, I've still seen many important weather and space events, but right now, if you were sitting next to me, you'd hear my foot tapping rapidly under my desk. I'm anxious for the next one: a space capsule hanging from a crane in the New Mexico desert.It's like the set for a George Lucas movie floating to the edge of space.You and I will have the chance to watch a man take a leap into an unimaginable free fall from the edge of space - live.The (lack of) air up there Watch man jump from 96,000 feet Tuesday, I sat at work glued to the live stream of the Red Bull Stratos Mission. I watched the balloons positioned at different altitudes in the sky to test the winds, knowing that if they would just line up in a vertical straight line "we" would be go for launch.I feel this mission was created for me because I am also a journalist and a photographer, but above all I live for taking a leap of faith - the feeling of pushing the envelope into uncharted territory.The guy who is going to do this, Felix Baumgartner, must have that same feeling, at a level I will never reach. However, it did not stop me from feeling his pain when a gust of swirling wind kicked up and twisted the partially filled balloon that would take him to the upper end of our atmosphere. As soon as the 40-acre balloon, with skin no thicker than a dry cleaning bag, scraped the ground I knew it was over.How claustrophobia almost grounded supersonic skydiverWith each twist, you could see the wrinkles of disappointment on the face of the current record holder and "capcom" (capsule communications), Col. Joe Kittinger. He hung his head low in mission control as he told Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunday.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause), he can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet (22.7 miles/36.53 kilometers). Here, "Fearless Felix" will unclip. He will roll back the door.Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, he'll be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end.Skydiver preps for the big jumpWhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes it's not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds.Even if everything goes as planned, it won't. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).It might not be the moon, but Kittinger free fell from 102,800 feet in 1960 - at the dawn of an infamous space race that captured the hearts of many. Baumgartner will attempt to break that record, a feat that boggles the mind. This is one of those monumental moments I will always remember, because there is no way I'd miss this.