A Technology Study Of Integration Of Earthquake Prevention And Disaster Reduction Information System Based On Web Services

In recent years, the information construction of earthquake administrationinstitutions has been developed rapidly with the great supports of human resourcesand funds from the government. Now some information systems for earthquakeprevention and disaster reduction have been established, which are isolated,isomerous and across-network. Hence it is required to strengthen communication andcollaboration between these existing systems. Strengthening communication andcollaboration between them is necessary. At the same time, the county plans to set upa complete framework for the digital seismic observational networks. These new tasksneed to construct new systems for operations and platforms. But when doing thisthing, the existing facilities must be protected as much as possible, and informationand application integration should be realized. It means that the integration betweenthe new systems and old ones should be implemented. Considering the currentsituations and actual requirements of the information systems for earthquakeprevention and disaster reduction, this work makes a study of the integration for thesesystems by using the Web Services technology.First, this thesis analyzes the problems that the systems are faced and theirsolution schemes. (1) Communication between users and servers. Usually there arefirewalls and agent servers between user ends and server ends, hence implementationby DCOM technology is very complicated. An ideal solution to this problem is toemploy the http protocol for communication because any machine that runs a webbrowser uses http protocol. (2) Interoperation between application programs. The WebServices technology can tackle this problem well. In the first place, Web Servicestechnology goes to communication by the http protocol, moreover firewalls and agentservers are open for http protocol. Thus, the problem (1) is resolved. In the secondplace, Web Services is a technology that is independent of hardwares, operationsystems and programming languages. This shields the foreign character. So theproblem (2) is resolved.Then the thesis presents the definition, integration architecture and keytechnologies of Earthquake Prevention and Disaster Reduction Information SystemWeb Services. Earthquake Prevention and Reduction Information System WebServices are some interfaces of certain function modules that are accessed by web.The remote system calls on the operations in the interfaces by Internet. Thus,implementation of system communication and integration is attained. The EarthquakePrevention and Reduction Information System Web Services integration architectureinvolves three kinds of roles (Web Services provider, Web Services requester and WebServices broker) and three sorts of operations (publishing, finding and binding). In theprocess of building Web Services, it also involves four sorts of important keytechnology: XML, SOAP, and UDDI. XML (Extensible Mark Language) is the basicformat of data expression in Web Services, which is independent of platforms andmanufacturers. Thus Web Services can let isomerous systems communication andintegration each other. With SOAP (Simple Object Access Protocol), different systemssend and receive normal XML data according to SOAP. SOAP is also of XML format,a kind of accessing protocol that is independent, universal and based on the XMLstandard between texts' objects. Carriers of standard XML message by SOAPtransmitting include HTTP, SMTP and HTTPS and so on. Because these protocols arestandard Internet protocols, Web Services can implement applications' incompactcoupling. WSDL (Web Services Description Language) is used to describe functionsthat Web Services finish and the services that Web Services supply. It is also of XMLformat according to certain criterions. WSDL is produced by servers and is providedfor clients. It includes detailed information about interfaces of Web Services anddetails of implementation. Clients determine whether the Web Service is used or notand how to use it. UDDI (Universal Description, Discovery and Integration) is a kindof criterion based on XML, which permits corporations to publish and findinformation about business functions and Web Services supplies. UDDI acts as WebServices broker corresponding to yellow pages of telephone number. It is a bridge inpublishing information.The product selection for Earthquake Prevention and Reduction InformationSystem Integration Web Services is also an important issue. I analyze and sum upsolutions of Web Services based on J2EE platform and .NET platform. Lastly, interms of actual requirements of Earthquake Prevention and Reduction InformationSystem, I choose two solutions of Microsoft and Oracle to make case studies.In this work, the geological data information query Web Service is the researchexample, which involves all the lifecycle of Web Services by Oracle9i JDeveloper,Oracle9iAS, UDDI Registry server and Oracle DB. The problems of research instanceare analyzed. Lastly, the qualification of function module deployment as WebServices is summarized as described below (1) When requiring accessing exclusivedatabase and/or it is very difficult for realizing native deployment or cost is very high,the module supplied as Web Services is very meaningful. (2) When the functionmodule requires a complex installation process or a complex and expensive hardwareconfiguration, using Web Services is possibly the best choice. In this case, providingfunction module as a Web Service will resolve many problems for users, because theyrequire no native deployment. (3) If it is often needed to publish a function module ofnew version, then it is also considerable to use Web Services. (4) It is better to publishthe function module that is dependent of often-changing data as Web Service. Theimprovement of updating data speed and changing data size will make the advantageof accessing the exclusive database better for remote computers.Finally, the Web Services interoperation character is studied by an instance,which is a call on geological data information query Web Service by the MicrosoftVisual Studio .NET 2003 developer tool. Some problems during the process areanalyzed and explained and a conclusion is drawn: it is limited for Web Services ininteroperation. The reason is that there are differences among Web Services solutionsfrom many companies. It is concluded that Earthquake Prevention and ReductionInformation System Integration based on Web Services has extensive meanings andexcellent development prospects.